# 1996 Chevy S-10 conversion



## brian_ (Feb 7, 2017)

What has changed in the last decade is largely the availability of modern components salvaged from EVs. That means AC motors, matching controllers, and lithium-ion batteries.

While lead-acid has obviously fallen out of favour, so have the LiFePO4 cells; salvaged EV battery modules are the now-affordable replacement. Production EVs typically run at around 360 volts (nominal), and both brushed DC and common aftermarket AC motors are typically suitable for much lower voltage, but there is an easy solution: use only some modules of a salvaged EV pack.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> LiFePO vs Li-ion


LiFePO4 *is* lithium-ion (Li-ion); LiFePO4 is just one of several cathode compositions used in lithium-ion cells. I assume that you are intended to compare LiFePO4 (also called "LFP") to the alternatives which have become much more common in recent EVs, such as NMC and NCA.


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## OR-Carl (Oct 6, 2018)

brian_ said:


> salvaged EV battery modules are the now-affordable replacement.



So I have been looking at the battery offerings from EV West, and I did some comparisons between the different chemistries (thanks for the correction there). The price per usable Kwh is about half for the salvaged modules compared to new LFP cells. How do they stack up in terms of real world use? The CALB cells claim like 2000 cycles, but is that at much smaller C-ratings than they likely would see in an EV? Have people on here who did early conversions with that style of battery had to switch them over, or are they still going strong? 



It clearly seems like Tesla put a lot of engineering into their batteries, but are there challenges with integrating them into a DIY setup? With 444 cells per module, and a string of 6 modules that is 2664 cells for the BMS to keep tabs on. I have not been able to find much info on that topic, and would really like some input on what others have used in the past. Also, what about cooling the batteries? 



I was also looking at the Netgain hyper 9 high voltage AC motor, and wanted to get peoples take on that for powering a little pickup.


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## Duncan (Dec 8, 2008)

My tuppence worth

NEW cells will have a failure rate - about 3-5% 

Salvaged OEM cells are much much LESS likely to have any failures at all

I'm using a Chevy Volt Battery - very impressed by the engineering and the quality

As far as motors are concerned

Forklift motors are cheap powerful and unsophisticated

New DC are expensive powerful and unsophisticated

NEW AC (like the Hyper9) are expensive and wimpy or VERY expensive

AC from a production EV - are streets ahead of anything else - but you need to handle the electronics


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## brian_ (Feb 7, 2017)

OR-Carl said:


> It clearly seems like Tesla put a lot of engineering into their batteries...


Tesla... and everyone else. Although Tesla sells the most EVs (after all, they have massive capitalization and no other product to sell), they're not the only EV manufacturer. They are also the oddball, being the only significant manufacturer to stick with little cylindrical cells, and that last to go to permanent magnet motors. Every manufacturer has a sophisticated BMS, every manufacturer other than Nissan uses active liquid thermal management systems, and they all work.



OR-Carl said:


> With 444 cells per module, and a string of 6 modules that is 2664 cells for the BMS to keep tabs on.


No, the BMS is not aware that there are thousands of cells (7104 among the 16 modules in this example). It monitors only the groups of parallel cells, so every EV with the common battery configuration of 96 cell groups in series monitors only 96 voltages and a few temperatures (one or two temperatures per module), regardless of whether a group has a couple of large cells or dozens of small cells (74 in the modules from a Tesla 85 kWh battery).



OR-Carl said:


> Also, what about cooling the batteries?


Circulating coolant is important at least to evenly distribute heat in among the cells (in modules designed for liquid cooling); whether the system is actually needed for cooling or heating depends on the operating conditions of the vehicle.


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## OR-Carl (Oct 6, 2018)

brian_ said:


> It monitors only the groups of parallel cells, so every EV with the common battery configuration of 96 cell groups in series monitors only 96 voltages



Ok, that makes sense, I think. When not charging or discharging, would all the cells in each cell group effectively have the same voltage, because being linked in parallel they can transfer power between each other and thereby stabilize their voltage? Like if there was one weak cell, the other 95 would all chip in a few electrons, and bring it up to an even footing with the others?


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## MattsAwesomeStuff (Aug 10, 2017)

OR-Carl said:


> When not charging or discharging, would all the cells in each cell group effectively have the same voltage


Any time cells are in parallel, they're going to be the same voltage. Charging, discharging, idling, doesn't matter. If they're in parallel, they'll be the same voltage.

This happens nearly instantaneously, only limited by how much current the batteries can discharge or recharge at, and the resistive limits of the conductors (nearly zero).

Under massive loads, it's possible that the voltage of some cells will momentarily sag slightly compared to others, but that's because they're all being flatlined and some don't droop as much. It's still corrected almost instantly when the load is removed.

It's a non-issue. Whether the modules are the same voltage as each other in series, is a much more difficult question because there's no self-balancing mechnism. Hence why you should have a BMS.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> Like if there was one weak cell, the other 95 would all chip in a few electrons, and bring it up to an even footing with the others?


Not "the other 95" (of the 96 groups in series), but the other 73 of the 74 in a parallel group within the module.


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## OR-Carl (Oct 6, 2018)

brian_ said:


> Not "the other 95" (of the 96 groups in series), but the other 73 of the 74 in a parallel group within the module.



Yes, sorry I misread the earlier post and was thinking that the standard was 96pXXs, but yeah, i was talking about the parallel cells within the cell group. (I was about to gripe that you cant read the old posts while formulating a response, then scrolled down and found them. 



So basically, a 5.3kw 22.8v Tesla module out of a model S, which has 3400ma cells in (74p6s) is going to look to the BMS like it was 6 cells in series, with a capacity of 251.6AH (74*3.4), right? 



So complexity wise, 6 of those modules in series would be electrically equivalent to 36x prismatic cells of 251AH capacity.


That helps make it seem less daunting. I am still a little worried about thermal run-away, but maybe after doing more reading it will seem like less of a problem. I will try and find some threads with info on thermal management.



I posted a response to Duncan's message, but it didnt show up. It flashed some message that I didnt quite catch - does anything that quotes an Admin need to get authorized, was that it? Anyway, hopefully it shows up, as I wanted to get some input on motors.


Thanks everyone for the great help so far!


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## brian_ (Feb 7, 2017)

OR-Carl said:


> Yes, sorry I misread the earlier post and was thinking that the standard was 96pXXs, but yeah, i was talking about the parallel cells within the cell group.


Good 



OR-Carl said:


> So basically, a 5.3kw 22.8v Tesla module out of a model S, which has 3400ma cells in (74p6s) is going to look to the BMS like it was 6 cells in series, with a capacity of 251.6AH (74*3.4), right?
> 
> So complexity wise, 6 of those modules in series would be electrically equivalent to 36x prismatic cells of 251AH capacity.


Yes, and yes.



OR-Carl said:


> I posted a response to Duncan's message, but it didnt show up. It flashed some message that I didnt quite catch - does anything that quotes an Admin need to get authorized, was that it?


I've never heard of that - it seems more likely to be a temporary glitch, or an attempt to post twice to the forum without enough time between them.


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## Cor (Sep 17, 2013)

OR-Carl said:


> I just picked up my donor vehicle today; a really clean '96 with a blown head gasket. I will post a picture when I get a chance.


If you are thinking about converting an S10 then take some leads from the existing (factory) conversions that are aplenty. There are several factory EVs, from the 97 Chevy S10EV to the 94 US Electricar and the many home conversions.
To get an overview and conversion details, take a look at the EV Album and filter for S10. I have my S10 with Nissan Leaf batteries on there, as well as my previous S10 with Lead-acid.
www.evalbum.com


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## dtbaker (Jan 5, 2008)

Dear OP,

I am one of the few 'old school' DIY conversion people that apparently still believes that a simple DC design is the way to go for the average DIY enthusiast.

I am NOT a fan of attempting re-use of OEM battery packs and/or AC motors.... because you'll find out very quickly that the expense goes way up, and the electronics to communicate between batteries with sophisticated chargers and environmental control, the controller/inverters with proprietary software/hardware/firmware, and sophisticated variable speed transmissions are all pretty daunting.

If you want a highly efficient Ev with a 200 mile range, buy one for $30-40k

If you want to BUILD one for $12k-$18k, I'd stick to:
- Warp9 DC brushed motor
- Zilla 1k or Soliton controller
- 120v or 144v or 156v x 130ah or 180ah or 200ah cells (CALB or other high quality prismatic in simple series)
- simple charger like Elcon/TCCH with LiFePO4 curve set for 3.5 or 3.55vpc at end-of-charge, top balance, and manually inspect/balance every 6 month.

If you visit http://www.EnviroKarma.org you can read thru the step-by-step build of my eSwift, and the move from original lead-acid to LiFePO4 (huge improvement)

Or.... if you want to 'rehab' one that's already *mostly done*, watch this forum, and buy one that is mostly done, and rehab whatever is missing or broken.


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## OR-Carl (Oct 6, 2018)

Hey dtbaker, I appreciate your input. I have been thinking about doing one of these conversions for a while, so in my mind an "old school" build like you describe sounds exactly like what I had been imagining. That being said, I do recognize that progress is being made, and I dont want to build something that is obsolete before its even done. I have a lot more research to do, obviously, but Its great to hear from people who have actually done it.


Thanks, Cor, I have looked at some of the S-10s on the ev album, and I think I have yours bookmarked, even. Lots of good info on there, I just need to compile it all and digest it, as its so hard for me to keep everything straight still.


I did want to get back to the post you made, Duncan, and get some more input on what you meant. Specifically, you said that new AC systems are expensive and wimpy, and that new DC are expensive and powerful. So, comparing a warp 11 to a Hyper 9:


The hyper 9 puts out 162 ft/lbs, and 120hp (this is probably its peak output?)

The Warp 11 only does 135 ft/lb, and is rated at 32 hp continuous. 



The price for the Hyper 9 is 4300, but that includes the controller, while the warp 11 is 3000 + at least 1500 for a controller?


It seems to me that they are both equally expensive, but is the AC version really wimpy? Am I missing something important in looking at the specs?


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## dtbaker (Jan 5, 2008)

OR-Carl said:


> ... I dont want to build something that is obsolete before its even done. ...So, comparing a warp 11 to a Hyper 9:
> 
> The hyper 9 puts out 162 ft/lbs, and 120hp (this is probably its peak output?)
> The Warp 11 only does 135 ft/lb, and is rated at 32 hp continuous.


My point is that a 9" brushed DC motor, 1kamp controller, and 120v-156v LiFePO4 battery pack is not obsolete.... plenty of power, range, and reasonably simple to build for the average DIYer.

A Warp9 with a zilla 1k controller and 156v battery pack is capable of putting out about 150kw of power for 10-30 seconds.... which is WAY more than you need for very decent acceleration! It translates to 'feeling' like a small-block v-8. The nice thing about the Warp9 versus an 11" or 13" motor is that the max revs are higher (maybe 5000 rpm), so your existing transmission is usable.

AC motors/controllers used in all the OEM evs are more efficient, operate at lower currents, and extend range with regen braking... true... but cost more, are more complex, and operate at much higher voltage which means more complex battery pack and battery management as well as lots of computer/control stuff that may be out of the area of expertise for the average DIYer.

You have to pretty much change your mindset when looking at electric motor specs versus gasoline. with ICE motors you are used to looking at PEAK horsepower and torque ratings, but with DC electric they typical post the CONTINUOUS power ratings because they are thermally limited as they are typically air-cooled.

The good news is that a vehicle on the highway going 60mph probably only needs about 20kw to overcome air and rolling resistance, meaning that a Warp9 is plenty. The peak of 150kw in the example above would likely only be for 10 second 'acceleration' events, limited by your controller output, and then in between your motor air-cools..... a Warp 9 is PLENTY for any average urban/suburban use, trust me on that.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> ... you said that new AC systems are expensive and wimpy, and that new DC are expensive and powerful. So, comparing a warp 11 to a Hyper 9...


Comparisons in this forum between "DC" and anything else are often intended to mean salvaged (e.g. from forklift trucks) motors, and so the assumed cost of the DC motor is minimal.

Comparisons to new aftermarket AC motors are usually intended to mean to the induction motors from HPEVS, not the relatively recently available permanent magnet AC motor which NetGain is selling as the HyPer9.

And in Duncan's comments "expensive and wimpy" AC motors are low-voltage aftermarket motors (such as those from HPEVS), not the even more expensive high-voltage PM AC motors such as the HVH series or those from YASA.


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## OR-Carl (Oct 6, 2018)

dtbaker said:


> My point is that a 9" brushed DC motor, 1kamp controller, and 120v-156v LiFePO4 battery pack is not obsolete.... plenty of power, range, and reasonably simple to build for the average DIYer.
> 
> 
> AC motors/controllers used in all the OEM evs are more efficient, operate at lower currents, and extend range with regen braking... true... but cost more, are more complex, and operate at much higher voltage which means more complex battery pack and battery management as well as lots of computer/control stuff that may be out of the area of expertise for the average DIYer.
> ...



Okay, that is all good info to know. I did not mean to disparage the performance of an "old-school" rig with an LFP battery and a salvaged DC motor. I suspect that it would more than meet all the criteria that I am aiming for. However, a Zilla 1k controller costs about 2300$, right? And a new warp 9 costs 2000 - So even if I got a free motor, I am *only* going to save 2 grand, compared to buying a pretty capable AC system, right? If I figure that I am going to sink 20k on this project, that only amounts to 10%, which just so happens to be the number thrown around for how much regen might add to my performance. How much do forklift motors cost, anyway, and how easy are they to obtain? (remember, I am really new to this ) I am still in the planning phase, so nothing is set in stone, but I just dont want to cut every corner I come to untill i know its actually a worthwhile shortcut. 


Has anybody out there used a Hyper 9 that could weigh in on its merits?


As far as batteries go, Prismatics sounds appealing for their relative simplicity, long cycle life, high discharge rate, and inherent saftey. But they are about twice the cost per Kwh of the used modules.



So right now, I guess I am looking to strike the right balance between complexity, performance and price. So far the only thing I think I will say is off the table for my build is going to be changing the drivetrain, and using production EV voltages (which I assume also precludes production EV motors). A little bit of software engineering I CAN probably handle (I think this is a pun, but I still basically have no idea what a CAN bus is or how it works ). Lots of reading to do...


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## dtbaker (Jan 5, 2008)

OR-Carl said:


> However, a Zilla 1k controller costs about 2300$, right? And a new warp 9 costs 2000


Your can find used ones for 1/2 if you re patient.... I would go with Warp9 over a used forklift motor, they have much nicer brushes/commutator and well worth the extra cost over a rusty hunk of crap you have to rebuild.



OR-Carl said:


> As far as batteries go, Prismatics sounds appealing for their relative simplicity, long cycle life, high discharge rate, and inherent saftey. But they are about twice the cost per Kwh of the used modules.


you CAN wait for used/decommissioned prismatics.... but be aware that if the entire pack is not from the same build or batch, then you are asking for problems keeping them balanced over time as they will 'drift' due to differences in internal resistance.




OR-Carl said:


> ... using production EV voltages (which I assume also precludes production EV motors). A little bit of software engineering I CAN probably handle (I think this is a pun, but I still basically have no idea what a CAN bus is or how it works ). Lots of reading to do...


before you sign up for that, poke around and see how many of the builds that have been completed and drivable on this forum are 120v-160v DC builds versus how many completed drivable conversions are 300v AC builds based on OEM parts.

Just as a frame of reference, I am a mechanical Engineer with years of experience in car mechanics, welding, machining, 'regular' software, but none in the EE stuff needed to talk to the OEM controllers, BMS and charging systems. The DC brushed motor, clutched transmission, simple controller, and simple top-balanced charger (without CAN bus and BMS ) is still the way to go in my opinion....


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## Duncan (Dec 8, 2008)

My tuppence worth

A forklift motor is exactly the same as a Warp - except for the paint job - and I have found our local elephants graveyard so they cost $150 - $200 each

P&S do a series of superb controllers for about $1000 each

Volt Battery Packs cost about $1800 for 16 kwh and are incredibly well engineered and come apart into nice sized modules for the DIY user


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## OR-Carl (Oct 6, 2018)

Sorry dtbaker, reading back over my own post, I can see that I was not being very clear - there is still so much I am trying to sort out.


So, the picture in my mind is coming down to these options, in order of my current level of interest:


Motor option A: New Hyper 9 144volt(or equivalent 120-144volt AC motor kit) total cost ~$4500


Motor option B: New Warp 9(or equivalent DC motor) + Zilla1k controller(or equivalent) total cost ~$3000-4500


Motor option C: Salvaged DC forklift motor + P&S controller(or equivalent) total cost ~$1200



Battery option 1: 6s 22.8v 5.3kwh Tesla modules with ~25kwh @80%DoD Cost: $9500 $/wh: 0.37



Battery option 2: 2s5p 60.8v 2.6kwh LG CHEM battery modules with ~21kwh @80%DoD Cost: $7400 $/wh: 0.35



Battery option 3: 45s 3.2v 180ah prismatic LiFePO4 cells with ~21kwh @80%DoD Cost: $11700 $/wh: 0.56


Battery option 4: Locally sourced modules from scrapped EVs, Size, cost, and availability: Unknown



Most of these option are of things that are in stock and ready to ship from EV west or other online retailers. I figure this is going to be a big enough project without it also turning into a scavenger hunt  (I am not ruling out other options, especially if I find things that can be dependably sourced when I want them).




I am also pretty sure I will want a BMS system regardless of battery type.
I will include some form of thermal management system if I use Tesla or other OEM modules that call for it.
I will plan on keeping the stock transmission and clutch.


I am not going to do anything with a voltage over about 144vdc.
I am not planning on using any motors or transmission parts from production EVs.


I really do appreciate all the input, so feel free to weigh in on any of this.


This is the donor vehicle, btw. It still needs a name...


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## brian_ (Feb 7, 2017)

*Battery module format and packaging*



OR-Carl said:


> Battery option 1: 6s 22.8v 5.3kwh Tesla modules with ~25kwh @80%DoD Cost: $9500 $/kwh: 0.37
> 
> Battery option 2: 2s5p 60.8v 2.6kwh LG CHEM battery modules with ~21kwh @80%DoD Cost: $7400 $/kwh: 0.35
> 
> ...


With the motor sitting where the bottom part of the engine was, and the transmission and shaft running right down the middle of the space between the frame rails, packing in battery modules will be a challenge. The Tesla modules are especially awkward, because they are so long and wide (although thin). I suggest seriously thinking about how they would fit in, and because you have the truck, making up cardboard or foam dummy modules and trying them in various places is probably worth the effort.

The Solectria E10 conversion of the S10 placed the motors behind the rear axle, to leave the space between the frame rails ahead of the axle clear for battery. I'm not saying that needs to be done (and it can't be with the stock transmission), just that packaging components is a serious concern.

The LG modules would be easier than the Tesla modules to fit in, due to their dimensions, and the individual prismatic cells would be even easier. There are, of course, other modules from other EVs and hybrids; the LG modules are probably the ones used in the Chrysler Pacifica Hybrid, and the modules from the Chevrolet Volt (also a plug-in hybrid) are popular in conversions. It would be nice to be able to run a line of modules on each side of the shaft ahead of the axle, as was typically done in lead-acid conversions.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> I will include some form of thermal management system if I use Tesla or other OEM modules that call for it.


Almost every modern production EV and plug-in hybrid uses a circulating liquid thermal management system. The common and notable exception is the Nissan Leaf (all versions).

Many modules use a "chill plate" system, with one face of the module (meaning one edge of each cell) clamped to a plate with heat transfer fluid circulating in it; the LG modules offered by EV West are an example of this, and the Tesla modules and Chevrolet Volt modules are notable exceptions. In a low-performance application, my guess is that it might be acceptable to just bolt big aluminum heat sinks (exposed to free external air flow) to that face of modules designed for a chill plate, if you want to avoid circulating fluid; however, this is only my guess and I don't know who has tried it.


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## brian_ (Feb 7, 2017)

*Documentation: Body Builder Guide*

This is the GM Body Builder Guide for the 1999 S-10:
S/T Truck
That's as far back as they have online, but the truck probably didn't change at all from 1996 to 1999... or in any significant way from 1994 through 2004. In case it's not clear, in GM's internal designations "S" was for the 2WD and "T" was for the 4WD, just as the 2WD & 4WD full-size trucks were "C" and "K".

This guide is used by companies upfitting trucks with service bodies and other equipment. It contains information about integrating with the truck, and dimensioned drawings which may be useful in planning component placement.


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## MattsAwesomeStuff (Aug 10, 2017)

OR-Carl said:


> So, the picture in my mind is coming down to these options, in order of my current level of interest:
> 
> Motor option A: New Hyper 9 144volt(or equivalent 120-144volt AC motor kit) total cost ~$4500
> Motor option B: New Warp 9(or equivalent DC motor) + Zilla1k controller(or equivalent) total cost ~$3000-4500
> ...


(Your $/kwh are actually $/watt-hour, but otherwise fine).

I think you've broken it down the same way the rest of us have, but for some reason the general best option, and the one everyone else is taking, seem to be your last option. I'd suggest you reconsider.

Without trying to be confrontational, but giving context, Dtbaker has a lot of experience with his build... from 10 years ago. Every time this comes up and he makes his suggestion on what's best (what he did 10 years ago) and confusion about why no one's building them like that anymore, and someone will come up with a breakdown of why it's a poor choice and why people don't build them that way anymore. Wash rinse repeat.

https://www.diyelectriccar.com/forums/showpost.php?p=1045453&postcount=30

In this case, you've demonstrated it yourself in your breakdown. 10-year old advice does not make sense to anyone and that's why no one's building them that way.

Warp9 + Zilla + LiFe Batteries is the most expensive way to go, for the worst result. That is the worst combination of price and performance.

If you want something better or equivalent in performance, you just do:

Forklift Motor + P&S Controller + Salvaged OEM batteries. It's like 20% of the cost and will outperform the other bundle. (Or, instead of $1000 P&S controller, spend $200-300 on a Prius inverter and Damien's DC board: https://openinverter.org/forum/viewtopic.php?f=14&t=275 )

...

On the reliability of new LiFe batteries, I don't think I've heard of *anyone* who didn't have failures on even a small pack (Dtbaker among them). The failure rate is completely ridiculous, I'd avoid them like the plague. Compare that to salvaged OEM packs, I think 1st Gen Leafs tend to have some junky cells, but in pretty much every other vehicle, a damaged pack is unheard of.

Do you want a pack where failure is nearly guaranteed, or, where success is nearly guaranteed?

Also, someone on the OI forums bought an 18kWh Volt pack for $750 US a couple days ago. So... $0.04/Wh. About 10% the cost of the Tesla or LG Chem cells you quoted above. Even at double that price it's still a steal.

...

As to whether a forklift motor is comparable to a warp9...

If you think about how pitifully small the market for DIY DC EVs has been even over 10 years (would it be egregious to say less than 1000? Less than 200?), versus how massive the forklift industry has been over the last 50 years with basically unchanged DC motors the whole time until the recent switch to AC (millions sold?), do you think that anyone was actually spending the time and money to engineer a DC motor for DIY EVs? Or do you think they just spec'd something right out of a forklift supply catalog and had it branded special?

Dtbaker also agreed they're equivalent: https://www.diyelectriccar.com/forums/showpost.php?p=1044933&postcount=35 "the most popular DC motors are basically forklift motors. The Warp9 from Netgain for instance." His comments here refute that, maybe he's changed his mind, but I wouldn't say it's a popular claim that they're in some way special or distinct from forklift motors.

Take a Warp9 and a 9" forklift motor, put them side by side and compare the two, they're functionally identical.

Electrical forklifts retire when their battery packs crap out and no one wants to replace them. The motors are generally just fine. Ask a forklift repair shop the last time they ever had to actually replace a motor. I suspect the answer is quite nearly "never".

Bearings might need replacing ($20), brushes might need replacing (don't bother, just find a different motor where the brushes still have 5-10 years of life left), but other than that, if it spins and didn't sit underwater for a month, it's good. Industrial equipment is massively overbuilt because of the cost of downtime, so the motors, comparatively, have an easy life.

Take along a car battery and a piece of scrap wire, spark the terminals and see how it spins up, there's nothing to them.

...

On AC Motors...

I'd strongly suggest not buying a new AC motor for the same reason I'd not suggest you buy a new DC motor. There's no point (even less point, AC motors have no brushes that wear out). An AC motor will last something like 1,000,000-2,000,000 miles. Vehicles crash and bodies rust away before their motors even enter adolescence. 

I'd suggest you look into the Toyota/Lexus larger hybrid vehicles for a motor/gearbox (GS450h?). They're designed for RWD and are pretty simple to repurpose. Damien's got a rolling vehicle using these. Him and Kevin are expecting 300hp, for something like, $500 total for the driveline/inverter and the only mod needed is a plate across one end of the gearbox so you can use both drive motors at the same time.

https://www.youtube.com/watch?v=F5XM6blwMlw

You can control it with a board you can build yourself for 50eur + components ( https://evbmw.com/index.php/evbmw-webshop/toyota-bare-boards/gs450h-bare-pcb ), or, throw 600eur at Damien to build and test it for you ( https://evbmw.com/index.php/evbmw-w...sted-boards/gs450h-vcm-fully-built-and-tested ). 

What about a battery charger? No problem, Damien's had success using the onboard boost converter as a battery charger (buck or boost).

Don't want a high voltage pack? No problem. Toyota didn't either (hybrid packs are small), so there's a boost converter that can jack the voltage from 200v to 500v to power the motors. Or, from whatever you have to whatever you want. 

In my opinion, once it's a little more polished and word gets out, basically everyone in the casual, non-race DIY EV world is going to switch over to either this for RWD, or the Prius for FWD. It's certainly just about the only thing I'd be recommending to people. You can literally get your whole driveline + inverter + open source control board for under $1000, pre-engineered by world-class engineering teams to automotive (high liability) standards. I dunno, maybe it'll be double that. But, practically pocket change compared to what anything else equivalent you could buy.

...

Since I made a point of bias, if you want to know my build-bias, I love cheap DC builds and have built a couple before (bike and motorbike), and I was reluctantly forced into an AC build for my car (free motor, didn't have any DC ones that week), but am reasonably happy with my choice so far (mid-build). I'm agnostic towards any particular technology, and there's nothing wrong with making the "wrong" choice if that's what is most interesting to you to.

Anyway, that's my two cents.


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## OR-Carl (Oct 6, 2018)

Thanks Brian, I will definitely be open to reconsidering my options once I pop the bed off and start getting a feel for the room I have to work with inside the frame. I am not planning on using this truck for bulk transport, so I am not going to rule out just putting a battery box in the bed, and slapping a lumber rack on it to make up for the loss of cargo space. 





MattsAwesomeStuff said:


> I think you've broken it down the same way the rest of us have, but for some reason the general best option, and the one everyone else is taking, seem to be your last option. I'd suggest you reconsider.



Hey Matt, thanks for all the great info. I am reconsidering, just not sure yet where I will land . I feel like you make a really good case for a salvaged DC build. I will have to do some searching for sourcing a forklift motor. That is sounding like something I feel like I could handle. Mostly, I am still feeling overwhelmed by the scale of this project, and take comfort in the idea of just buying off-the-shelf items (though I can see how its not really the best approach in terms of getting the most value). For some reason I really like the idea of regenerative braking, but I know that it is not really a game changer in terms of range, so it might just be better to let that idea go for my first build.



The same feeling of uncertainty goes for used modules - I see their benefits, but dont really know where to go about starting to hunt for them. It doesnt seem like something your average local pick-n-pull is going to stock, but I have never been in the market for them. I am luckily not far from Portland, and there are a lot of hybrid and BEV vehicles on the road around here. Other than salvage yards, are there other good sources for used electric vehicle parts?


Hopefully as I keep reading, things will become more clear, and it will all seem less overwhelming. 



I would like to get a broad strokes overview of how the CAN bus fits into the modern EV conversion picture. I read the wikipedia page on it, and feel like I have a basic grasp of what it is doing. Basically it will allow my BMS to talk to the charger and the motor controller, right, using magic? What are the main functions it needs to do? Prevent over-voltage? low voltage? too many amps being pulled by the controller? And is it pretty straight-forward to program in the values you want, or do the components come preset with values from the factory?


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## dtbaker (Jan 5, 2008)

MattsAwesomeStuff said:


> (Your $/kwh are actually $/watt-hour, but otherwise fine).
> 
> Without trying to be confrontational, but giving context, Dtbaker has a lot of experience with his build... from 10 years ago. Every time this comes up and he makes his suggestion on what's best (what he did 10 years ago) and confusion about why no one's building them like that anymore, and someone will come up with a breakdown of why it's a poor choice and why people don't build them that way anymore. Wash rinse repeat.


Matt, for a guy who says you don't want to be confrontational, you do a great job of it..... reminds me why I stopped visiting this Forum and contributing. I get pretty sick of you writing about superior solutions when you don't have a car up and running yet.

Cars are lots different than bikes, or skateboards, or whatever.... Lots of mass, lots of energy. I'm not 'confused' at all about why I recommend DC, 120v-160v, and large format prismatics for DIY. The short answer is it is the simple, effective, off-the-shelf way to go for non-EE types. Yes there seem to be a couple people who have figured out how to pull apart OEM control boards, re-program, and pull apart Volt or Leaf or Tesla battery packs/BMS/Chargers.... but it does not see to be to the stage of plug and chug like the 'old' solutions you turn your nose up at.

My questions in the recent past regarding the use of used battery packs from OEM Evs were in effort to check and see if any/many people had solved the problems with using them effectively in DIY EV build. The problems I see with using them still exist... with lots of little cells, and lots of connections, and a configuration designed to run at 300+v and less than 300 amps; that doesn't seem to work well with available DC brushed motors (forklift or Netgain) that are designed for 160v and in Netgain Warp9 case beefed up to handle bursts of 1000amps.

That by the way is why I said the Warp9 is 'basically' a forklift motor, but it IS beefed up with heavier brushes, springs, insulation to handle higher voltages and more amps that the same size 'used forklift motor'.... which is the basis of my recommendation that there IS a difference.




MattsAwesomeStuff said:


> In this case, you've demonstrated it yourself in your breakdown. 10-year old advice does not make sense to anyone and that's why no one's building them that way.


wow.... does it occur to you that you may be making a mistake by speaking for 'everyone' ? I would really like to know how many EV conversions have been COMPLETED and put on the road in the last year with used OEM battery packs, AC motors versus builds COMPLETED and on the road with DC and large prismatic.

How about your build? up and running? have you solved all the electronics issues with batteries, controller, charging and BMS? with off-the shelf solutions the OP can go buy and install?



MattsAwesomeStuff said:


> Warp9 + Zilla + LiFe Batteries is the most expensive way to go, for the worst result. That is the worst combination of price and performance.


I never said it's best or worst and probably not cheapest. I will say it is effective and quicker for the average DIY garage mechanic. Time is money in my book, which is why I still maintain the Warp9 + Zilla/Soliton/P&S + LiFe (100-200ahr large cells) is not a bad way to go.




MattsAwesomeStuff said:


> If you want something better or equivalent in performance, you just do:
> 
> Forklift Motor + P&S Controller + Salvaged OEM batteries. It's like 20% of the cost and will outperform the other bundle. (Or, instead of $1000 P&S controller, spend $200-300 on a Prius inverter and Damien's DC board: https://openinverter.org/forum/viewtopic.php?f=14&t=275 )


certainly cheaper. I don't know about the reliability of P&S controller, no personal experience there. the salvaged OEM battery route seems like trouble since the wiring is not designed to carry 1000amps you'll want at lower DC voltages. If you're running an AC motor/inverter, then I'd say go for the used OEM packs.



MattsAwesomeStuff said:


> Take a Warp9 and a 9" forklift motor, put them side by side and compare the two, they're functionally identical.


they really aren't..... for reasons I put in above. I wish you'd stop sounding like the ultimate expert on things that you don't really know about.

The whole goal of this Forum as I understand it is to ask questions, share facts, share first hand experience on what works, and what doesn't, and HELP rather than talk in absolutes and opinions. 

When people use words like always, never, best, worst, everybody and nobody... I kinda get pissed off and don't feel like .
contributing any more.


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## OR-Carl (Oct 6, 2018)

Hey, Lets try and refrain from too much ranting, Okay? I am interested in everyones opinions, but lets maybe stick to the topic, and not get into the weeds dissecting each others words. I do not really want to insert myself in some feud over the "only way" to build an EV. It seems clear that there isnt one, and nor do I feel that I need to be defended from anyone elses biases. At the end of the day, I will take everything that I can learn from you all, and make my own choices. 



I think you both present valid arguments, so I will simply ask that everyone who wants to contribute to this thread stick to sharing their own opinions, and present them as such. Feel free to disagree, and share your own experiences, but dont fill this thread up with dredged up animosity, please!


So moving away from batteries and motors for a bit, I would like to hear peoples experiences with different battery management systems. Does a BMS get factory programmed, or are they programmable by the user (who does not have an EE degree)?


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## Duncan (Dec 8, 2008)

As somebody who IS using a forklift motor in a car
And who IS using OEM batteries
And who IS using over 1000 amps and over 150 volts

(1) Forklift motors are tough beasts - in six years of abuse I have killed one but the failure came from my poor handling technique when I first advanced the timing

(2) OEM battery modules are very easy to use

(3) You can easily reconfigure an OEM battery to a different voltage


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## Ocean (Dec 20, 2016)

Hi Carl,

To be blunt, I'm wondering if you would consider taking over my Chevy S-10 Conversion project. I know you already have a donor, but mine is basically the same as yours but with an extended cab, paint job almost as good. Maybe the parts are interchangeable so you could maximize it. Also, the ICE is already removed, as well as the gas tank and all gas lines. I started building battery boxes for Chevy Volt modules to be mounted (hung) along side the drive shaft.... they just barely fit.... check out the link here (has pics): 

https://www.diyelectriccar.com/forums/showthread.php?t=201449&highlight=chevy

You get a working 11" Kostov DC motor (forklift essentially although they did at one point market themselves to the ev world) rated for 144volts, with interpols. Also you get a second motor that needs a new bearing, and also an additional Rotor with both bearings, also a new brush ring and a new set of brushes, along with the complete adapter for the S-10 Transmission (5 spd).

As noted in my listing you can take everything with or without the actual Chevy Volt batteries. I really just have too much going on and I'd like to pass it on to someone who would love to carry it forward. The price is basically what I paid for it.

I'm about 1.5 hours south of Mt Shasta on I-5. I know it's a ways from N. Oregon. You'd have to bring a car hauler (or rent one down here for the trip back). You could sleep here if you wanted too.

There's also an opportunity to have a look at my other build which is operational - Bradley GT2, with 8" DC Motor, P&S Controller, and Chevy Volt Batteries.

As to one comment in this thread about the OEM packs running higher voltage and so having connections for lower amperage - that's a good point and also a good reason to run packs in parallel. Parallel packs share the amperage so if your OEM pack originally ran 150 amps @300v for example, you could safely re-configure that pack to run 300 amps @ 150 volts where the pack is split in two and the two smaller units are running in parallel.

I have 4 parallel Volt units in my Bradley running 150volts (36S, max full charge voltage), and the P&S controller can do 1000 amps, and I almost will never use even half of that.... so it's a pretty good setup.

I do not have a BMS. I check the individual Volt cells every once in a while. They are remarkably stable and seem to keep a very good balance with each other. That being said, I've been looking into very simple balance boards which move up to 5 amps from any cell to any other cell in order to maintain balance within the pack. I have two of these balance boards (4S and 8S) which I will be wiring up soon to see how they perform on my Home Solar Energy system which is off grid, running CALB 100 amp hour cells from an old ev I got on a deal - and I will say they drift A LOT. If the balance boards work I will report. I'm hoping they do. They look pretty nice - well built. They do not bleed cells down with resisters, but rather transfer energy from one cell to the other.

Anyways, have a look at the link above, and PM me in interested.

Good Luck!!!


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## dtbaker (Jan 5, 2008)

OR-Carl said:


> I do not really want to insert myself in some feud over the "only way" to build an EV. It seems clear that there isnt one, ...I will simply ask that everyone who wants to contribute to this thread stick to sharing their own opinions, and present them as such. Feel free to disagree, and share your own experiences, but dont fill this thread up with dredged up animosity, please!
> 
> 
> So moving away from batteries and motors for a bit, I would like to hear peoples experiences with different battery management systems. Does a BMS get factory programmed, or are they programmable by the user (who does not have an EE degree)?


well said Carl. I admire the cut to the chase in search of information.

discussing BMS may well start another Holy War, as well as the related topic of whether it is preferable to top-balance, or bottom balance. There are several moving parts in this discussion, and I'll relate MY choice, why I did it, and what the outcome has been.

After much research and questions on the Forum I went the route of:

- initial top-balance with a revolectrix quick charger cell-by-cell to 3.65v before hooking up the pack. The idea was to start off as close as I could with a top-balanced pack.

- I designed to a limited range on purpose as I live in a compact town and wanted to balance range/performance/cost.... my first eSwift used 120v x 100ah (38 cells), the eMiata used 156v x 130ah (48 cells). In both cases I decided to use a Cheap/Slow 1500watt Elcon charger, and charge off 110vAC overnight.... fast enough for typical 20 mile daily use.

- I decided to 'go comando' completely without BMS or CAN bus control of the charge, and just let the charger do its programmed charge curve. At the time 2008, and 2012, I did not like the complexity, cost, or parasitic drain of the various active/passive/shunting BMS solutions available. My hypothesis was that cycle-induced 'drift' at the end of charge could be checked periodically, and re-balanced if needed to prevent any single cell from going overvoltage. Not too hard to check once in a while with 38-48 cells.

- I did this KNOWING that both over-voltage, and undervoltage are serious problems for lithium. In a series pack, whatever cell goes too much higher than others at end of charge gets damaged, as does any with less capacity than gets run to 100% DOD while under load.

- results: as expected really... I lengthened time between manual check and re-balance to about 1000 miles, which caught everything before they got too out of whack end of charge. I also found this was 'safer' by reducing the end of charge pack voltage to an average of 3.50 vpc.... 
The only failed cells I've had were from loaning the cars to friends who drove until they stopped, ignored warnings, and zapped cells on the bottom. predictable result, driver error enabled by lack of 'idiot-proof' cell level warnings.

- conclusion: I trust the charger, top balance periodically, and don't loan cars to idiots any more. 15k miles on eSwift, 25k on the eMiata with no failures other than the driver error events..... I'd build another one this way; and take another look around for a simple cheap cell-level warning system for both over and under voltage to see if I could find something I can trust at a reasonable price.


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## MattsAwesomeStuff (Aug 10, 2017)

dtbaker said:


> I'm not 'confused' at all about why I recommend DC, 120v-160v, and large format prismatics for DIY.


I didn't say you were. Read what I actually wrote.

You've said things like "I don't see why people aren't still doing things the old school way... Warp 9, Zilla, CalB LiFe batteries...". 

Hence, why I said you are confused about why people do things, since you were asking why they've fallen out of favor or, perhaps why people don't see the "right" way of building a conversion, the way you have.



> it does not see to be to the stage of plug and chug like the 'old' solutions you turn your nose up at.


Again, you have to actually read what I wrote. I didn't say any of that.

I didn't "turn my nose up" at the old solutions. I said I've built a couple using that, and planned on my car being the third, and got reluctantly forced into AC because that's what the junkyard had at the time. I like simple DC builds.

Just because someone disagrees with you on a subject, doesn't make them your enemy, and doesn't mean they disagree with you on everything.



> My questions in the recent past regarding the use of used battery packs from OEM Evs were in effort to check and see if any/many people had solved the problems with using them effectively in DIY EV build. The problems I see with using them still exist... with lots of little cells, and lots of connections,


"lots of little cells"? Who's using little cells (other than me, who's using recycled 18650s from tool packs, not OEM vehicle packs, which I don't recommend anyone else do)? 

You paint the fact that OEM vehicles use a BMS as a "complicated problem", but your solution is to not even use a BMS. Apples to apples, you can't claim it's some complicated necessity for others, but not for you.

Your builds are still running 50-ish cells with no balancing. So they're in same danger ballpark as 100-cell OEMS with no balancing. It's not like you're getting away with a 4s pack.

I think Duncan observed a while ago that literally everyone who uses new large-format LiFe cells has had multiple cell failures on their builds. If there's a place where you *need* a BMS, it's if you want to gamble on new LiFe cells.

Certainly, if you're being consistent and agnostic about your risks, running at OEM cell counts is offset by using OEM batteries. By at least an order of magnitude. Plus, there's no reason you'd have to run at OEM cell counts.

To build the same pack, if you choose to go with new LiFe cells you're looking at minimum 10x the failure rate (if not 100x), and 5x the cost versus used OEM.

If you're sticking with the same voltages, you have no added risk. But even if you want to run at OEM voltages, at 200% the risk, you're still like 5x as safe without a BMS there as you are with large prismatics at half the voltage.

I can't think of a single reason to use large form factor LiFe cells.



> I would really like to know how many EV conversions have been COMPLETED and put on the road in the last year with used OEM battery packs, AC motors versus builds COMPLETED and on the road with DC and large prismatic.


I don't think that makes your case one way or the other, but it's an interesting question.

Since used OEM cells have become available, how many people have even bothered with failure-prone, bad-value large format prismatic cells? Especially DIYers?

I'm struggling to think of a single time in the last 2 years that I heard of anyone even buying any. The only ones I see come up for sale are from people who don't want to sink more money replacing their failed prismatic cells, and they're sold to people who do want to sink more money into replacing their failed prismatic cells. The dead eating the dead as it were.

There is more choice involved than just "All OEM" vs. "All 10 year old tech". You can pick and choose.

To your question... very few people have tackled the task of removing the whole electrical system out of an OEM EV and tried to replicate it in place (i.e. tried to trick their donor car into thinking it still exists). But those that have, seem to have done it successfully. I agree with you that it's a daunting task that's not for the casual.

But how many people have built AC systems off-the-shelf, or used OEM batteries? Basically everyone the last few years. And the trend is certainly increasing in that direction. Damien just yesterday ran off dozens of pre-populated boards to repurpose a variety of AC inverters, because there was a lineup of people wanting that next run of boards.



> How about your build? up and running? have you solved all the electronics issues with batteries, controller, charging and BMS? with off-the shelf solutions the OP can go buy and install?


So, you're going to play this "I have a finished car, you don't, so I'm right" card, but, aside from trying to brag or turn it personal, I don't think it's relevant.

You'll have to separate whether you're criticizing my build, or my advice, because they're different.

I'm not being egotistical and saying that my way is everyone's way. Which is why I'm not even recommending what I'm doing to others. I recommend to people what seems like the best option *for them*, not "everyone do what I'm doing."

Most often, I recommend people use a large DC motor for their projects when I consider what they say they want to accomplish for their budget. I've done that at least a half-dozen times in the last year. And I'm hesitant to recommend anyone attempt an AC build (until very recently).

I work on my EV about 1 night a month and in general I'm poor at completion. I haven't even started the EV part of my conversion, I'm welding two different junkyard cars together first.

Does that say my project is too difficult and I would be done if I'd chosen DC? No.

Have I solved all the issues?

Well, I drove 3000 miles to buy two junk cars for $200 each because I'm cheap and I like rescuing/repurposing things.

Batteries:

- I got thousands of recycled 18650s for free. So I'm using them. I'm not recommending that to anyone. I've tried to talk other people out of it because *my* solution isn't suitable for everyone.
- My advice is to buy used OEM cells, and, yes, that's a solved problem. Just go buy some. I can't think of anyone who has done anything else in the last year.

Controller:

- I spent $157 on a Prius controller and about $75 in parts for the control board because I want a cheaply-built, pre-engineered solution, and I'm interested in DIY, not DI-Buy. But I could have just paid $1000 for Johannes to build me one of his. Same price as a P&S DC controller. Less than a Zilla.
- My suggestion is that he probably wants a DC motor, but to use a junkyard one. Since his top preference was AC, I suggested he not spend thousands on a new AC motor.

Charging:

- I'll probably use a variac at first to charge, because I already have one.
- If I didn't, I'd use a large capacitor to limit current, a 1 component solution.
- If I wasn't, I'd use a plain bulk charger, same as you're suggesting. Spend $1000 and have a charger, problem solved.
- Longer-term, Damien has already demonstrated repurposing the boost module on the inverter I already have as a battery charger. So that's what I expect I'll use.
- I haven't recommended any battery charging solution, because it doesn't matter what he chooses, they're all equally easy to charge. It's a non-issue.

BMS:

- I don't plan on having one, same as you. I'll top-balance once a season to check.
- I'll probably add a $5 Bat Man like Duncan did so that if anything fishy happens on my pack balance-wise, I'll get a warning, which is all you need anyway.
- I could spend $1000 on a fancy BMS system if I felt like it.
- I haven't made any recommendation for a BMS.

So, in conclusion, my personal build has *most* of the problems solved (and the existing problems are from me being cheap). My suggestions are 100% solved problems. So I don't see your point.



> I will say it is effective and quicker for the average DIY garage mechanic. Time is money in my book, which is why I still maintain the Warp9 + Zilla/Soliton/P&S + LiFe (100-200ahr large cells) is not a bad way to go.


Well, I think there are many solutions that work for people depending on their preferences, but about the only thing I would say *is* a bad way to go is spending $10,000 on failure-prone new large prismatic cells. You get something at least 10x (if not 100x) as unreliable, at 5x the price.



> The whole goal of this Forum as I understand it is to ask questions, share facts, share first hand experience on what works, and what doesn't, and HELP rather than talk in absolutes and opinions.


First hand experiences are opinions.

Sharing that someone noticed that they've never even heard of a LiFe pack that *didn't* have issues is sharing what works and what doesn't.

Sharing prices and options is sharing facts.

You make it seem like your opinions about the way you built things 10 years ago are valid, but my observations about what people are generally up to these days, aren't.


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## OR-Carl (Oct 6, 2018)

Jesus, really? I took the liberty of cutting out the parts that repeat old information from this thread just for the sake of argument - I really do not need to hear the same material over and over. I think I got it. I am always interested to hear about the decisions other people are making in their builds, though.



MattsAwesomeStuff said:


> I didn't say you were. Read what I actually wrote.
> 
> You've said things like "I don't see why people aren't still doing things the old school way... Warp 9, Zilla, CalB LiFe batteries...".
> 
> ...





Duncan, I had a question for you about OEM packs. I found a posting on CL that resell scrapped battery modules here locally. Their offerings:


Mercedes/Tesla - 36kWh - $5000
This is a battery made by Tesla for the Mercedez-Benz B200 2017.
Kia Soul - 27kWh - $4500
375V battery for the Kia Soul EV 2015-2018.
Nissan Leaf - 24kWh - $4000
2012-2015 models. 360V battery.
Honda Fit - 20kWh - $5000


Im interested in that tesla/merc pack, which according to the seller has 12x 3kwh 25.9v modules. Now running them 6s2p would give me like 155v, but are parallel strings a problem with OEM modules? I seem to recall reading a thread that argued that, but now I cant seem to find it again. 



I am guessing that people must be doing parallel arrangements, though, right? Would love a run-down on any pros and cons. 



These prices are about half of what they charge at EV-West, and not having to ship them is nice. They offered them as full units, or stripped down to the modules - any opinions about which would be prefered? I dont really like the idea of digging into a 400v battery pack as my first introduction to lithium batteries, but are there goodies inside there that are worth getting? And as far as not buying DOA modules - is it as simple as taking a voltage reading on each module? Would love to hear any advice people have on checking out used batteries.


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## Duncan (Dec 8, 2008)

Hi
There are some excellent goodies in an OEM battery pack - at least there were in the Volt one

Paralleling

What you should do is parallel at the cell level - which is a lot easier than it sounds as each module will have "cell level" connectors for it's BMS

You need the beefy connections for the module level - but the cell level only needs thin wires - and fuses would be good idea - just small automotive fuses would be fine

The only battery pack I have taken apart was the Volt one and it was remarkably safe 

The pack was split into two by the "service fuse" and there were connection between the modules - once they were removed you would have to work very hard to electrocute yourself

https://www.diyelectriccar.com/forums/showthread.php/2012-chevy-volt-battery-93101.html


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## MattsAwesomeStuff (Aug 10, 2017)

> are parallel strings a problem with OEM modules? I seem to recall reading a thread that argued that, but now I cant seem to find it again.


Generally, no problem.

If you look at what's inside a Tesla pack, they're just dozens of small cells paralleled together, then groups of those in series.

Any group of cells in parallel are going to be forced to have the same voltage and share equally.

What you want to avoid, if you can, is just paralleling the end points. I.E. Don't parallel two 150v packs at just the + and - ends.

That'll work, but now you'll need 2 BMS's. Or, if you're okay risking no BMS, whatever that risk was you now have double it because an imbalance could happen on either side.

So what's best is if you find a way to parallel everything at the cell level.

If you have Pack A and Pack B, you want to parallel:
1a to 1b.
2a to 2b.
3a to 3b.
4a to 4b.
...
Etc.

Not big fat heavy wires, just a small connection so that they can't get out of balance, all cells in parallel are forced to be matching the same voltage on their counterparts, and then you can pretty much treat them as one large cell.



> I am guessing that people must be doing parallel arrangements, though, right?


Generally not, but as a matter of constraint, not technical obstacle.

OEM packs are generally a form factor large enough that they'll be 1p of everything. So, if there's 96 cells in series, there's 96 cells total (not 2x96, or 3x96).

That means for most packs, the smallest you can divide them into is the amount they're already divided into.

Because OEM vehicles have the luxury of creating their frame and body to compactly/perfectly fit their battery pack, and/or have selected a size of battery pack that they can fit into their body/frame... you end up with about the maximum amount of battery you can efficiently cram into a vehicle. This applies both to volume and weight being where is designed.

When you go to do your conversion, you do not have the luxury of having a body/frame optimized for the size/shape of your batteries, nor batteries sized vice versa. Neither for volume nor weight. You're going to have to sequester them away wherever you can make them fit, and there will always be wasted space. I.E. If you can fit 1.5 modules wide... that rounds down to only fitting 1 module and having half a module's worth of useless space.

With me so far?

People generally want as much range as possible in their conversions. "All the battery" is barely enough.

So, you *don't* have a choice of adding 10% more battery, or 20% more in parallel. And if you want to target a very specific voltage, nor do you have the choice of taking away 10% or 20%. They'll be the size that they are.

... and the size that they are, was as big as the OEM could make them in their optimized frame. Which for you... is too big on an unoptimized frame.

If your quantum of battery is already "almost too big", basically no one is saying "take that and double it for a 2p arrangement", or "Let's do 3 of each of these in parallel."

Generally, when people are re-using OEM batteries, they're concerned about skimping on less than the full amount of cells in series, because the higher the voltage the faster the motor will spin, and you don't want to run into issues of maxing out your top speed.

If you chop a 400v pack into a 200v pack (or a 2x200v pack in parallel) and use the same motor, it's going to have 50% the max top speed.

Another reason it's not done is that most controllers can lower the voltage by affecting the duty cycle, but not raise it. So you can feed your controller a higher voltage than the motor is good for, and the controller chops it down.

Another reason it's not done is that the higher the current the higher your losses. Voltage is "free" in terms of loss, so to run efficiently, you want to keep your pack at a higher voltage. This is squared, so, it's even more efficient than linear. It also means you'll have thinner, lighter-duty power cables, linearly.

Another reason it's rarely done, even for large prismatic cells back in the day, is because you can generally buy a single cell 2x as large, for less than 2x the price of smaller cells. So people, same as OEM, tend to pick the largest form factor they can fit into the vehicle and go with that, not multiples of smaller cells in parallel.

The only place you'd tend to see paralleling of OEM packs is when someone is taking multiple whole packs from a smaller vehicle and putting them into a bigger vehicle (like, 2x as big). Or, when doing a lower-voltage DC build with OEM packs (though lots of people just go with a pack half the size).

... food for thought, you can fairly easily chop Tesla modules in half (electrically) and un-parallel them. So if you want smaller building-blocks and only want half a Tesla worth of batteries, you can get away with less. But, because of their fame and popularity, Tesla packs tend to go for a premium for their kWhs compared to less prestigious packs, since they're gobbled up by those that are performance-minded.

On my build, by coincidence, my source of free batteries is tiny, they're 18650s (thumb-sized). This works out great for me because I'm converting a tiny car. This lets me pack them in any way I want, and also arrange for a pack size suitable to what I could fit. If I had to buy OEM cells, I don't know that I'd have enough room to fit enough of them to get the voltage I need.

For example, this would be especially true on a motorbike, and is dominatingly true on an E-bicycle, where you don't have a hope of fitting as many cells in series as you can on a car. So they have to go with tiny form factor, a few in parallel.


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## Ocean (Dec 20, 2016)

Carl, did you say you are living off-grid? Just going to mention here that those Tesla / Mercedes packs are PERFECT drop-in replacement for 24v nominal inverters, or two in series for a 48v inverter. I have three of those 3kWh units. They are 7s (7 cells in series) - giving them a range of 21 - 29.4 volts. They perform awesome in my home off-grid system.

As far a car battery layouts go....

I will say I am running 4 chevy volt modules in Parallel (150.4 volts @ full charge) with a P&S controller, and I do not have a BMS. I keep an eye on it. I am taking that risk but I will say those packs are pretty well balanced when I got them... and they drift very very little. Each individual cell in a volt pack is actually three cells in parallel btw (the 1st gen packs anyways)

The Volt packs are super easy to dis-assemble and yes, as someone said, you do get some other goodies. Some use-able high voltage contactors (three @ low amperage, 2 at high amperage I think about 120 amps rated). This BTW indicated the operating amperage of the original Volt pack - max about 120 amps @ 400 volts. That's why it makes sense to parallel the packs. The Volt packs are 47 - 50 Amp Hour units. You probably want 200 or more amp hours if you are going to run 200 or more amps, which you will definitely need to move your truck around up and down those hills. Tesla units (from a Tesla S for example) are 250 amp hours. the Mercedes / Tesla units are 120 amp hours.

food for thought!


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## OR-Carl (Oct 6, 2018)

Duncan said:


> What you should do is parallel at the cell level - which is a lot easier than it sounds as each module will have "cell level" connectors for it's BMS
> 
> You need the beefy connections for the module level - but the cell level only needs thin wires - and fuses would be good idea - just small automotive fuses would be fine





So, I made this diagram of a hypothetical 3s2p setup to try and make sure I understand:












The large box is the module, with in this case 7s cells (or cell groups) inside. The green lines would be connecting the individual cells, and would be using the BMS wiring- so I am not having to dig into the module to get to the connection points on each cell. If I routed all the green lines to a fuse box, i could also have my BMS monitoring the cells from there, yeah? 



How big would the green wiring need to be? If I understand the operation of the BMS correctly, it senses when a cell is nearing full charge, and shunts power away from that cell so that the other cells can catch up without overcharging the cell that is at the higher voltage. Does the size of the charger play any role there? In other words, if I am charging at a faster rate, does the BMS shunt more power?


Nobody mentioned things to look out for when buying used battery packs, incidentally. Have people mostly found the process to be pretty foolproof? The cells can get overdischarged, which flips their polarity and ruins them, right? Has anyone had/heard of anyone buying a battery pack, only to find that all/some of the cells are unuseable?


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## Duncan (Dec 8, 2008)

That image is great

The BMS wires are very thin - so that is all you need 

The BMS moves tiny amounts of current - so it does not need thick wires

I'm NOT using a BMS - I have a Batt Bridge 
http://www.evdl.org/pages/battbridge.html

Which will tell me if a cell or cells fails

And every six months or so I go around with a voltmeter and check my cells - that Chevy Volt thread I referenced shows you how

To Ocean's point about maximum current - disagree - I'm pulling 1200 amps from my pack - admittedly for a few seconds only 

The Volt will pull 300 amps for a couple of minutes - everything is designed around that - the contactors can only reliably break 120 amps - BUT in an AC system they NEVER need to break the full power - if the controller goes closed circuit the motor STOPS 

Battery packs
As far as I know all OEM packs will shut down before they get that low - so that should not happen
I would worry about physical damage from the crash - but an external examination should show that


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## OR-Carl (Oct 6, 2018)

Duncan said:


> I'm NOT using a BMS - I have a Batt Bridge
> http://www.evdl.org/pages/battbridge.html
> 
> Which will tell me if a cell or cells fails
> ...



Thanks, Duncan, I like that battery bridge idea. Seems like it would be a nice backup system to give you a sense that everything is looking good in your pack. Still, I would like to be able to use the charging ports at the local grocery store, and know that if a cell dies while i am not watching, that the whole thing is not going to catch on fire in the parking lot. 



I am trying to get through that thread, its... pretty long. Any idea on what page you talk about balancing?







Duncan said:


> To Ocean's point about maximum current - disagree - I'm pulling 1200 amps from my pack - admittedly for a few seconds only
> 
> The Volt will pull 300 amps for a couple of minutes - everything is designed around that - the contactors can only reliably break 120 amps - BUT in an AC system they NEVER need to break the full power - if the controller goes closed circuit the motor STOPS



Yeah, I will hopefully not be pulling 300 amps all too often, but it would certainly be needed to get any sort of acceleration on some of the hills I have here. Ocean, was your point that from a longevity standpoint, keeping the amp draw of your maximum load low in relation to your AH rating of your pack is probably a good idea? That is to say, try and keep your max load as close to 1C as possible? 



Duncan, would you clarify what you mean when you say "BUT in an AC system they NEVER need to break the full power". Are you refering to the fact that since AC cycles through zero volts with each cycle, breaking the current flow is much easier? I am not sure I understand how that would translate to lower current ratings on the DC side of things.


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## MattsAwesomeStuff (Aug 10, 2017)

OR-Carl said:


> Are you refering to the fact that since AC cycles through zero volts with each cycle, breaking the current flow is much easier? I am not sure I understand how that would translate to lower current ratings on the DC side of things.


https://youtu.be/Zez2r1RPpWY?t=54

Zero crossings make a huge difference in the ability to extinguish arcs.

You'd still have an issue between your battery and controller (if that was an issue), but at least your motor can be shut off easily-ish if it locks on.


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## Duncan (Dec 8, 2008)

Hi
The main thing IMHO is that if a DC controller fails closed the whole battery power goes to the motor and it tries to kill you

If an AC controller fails closed it puts a lot of current down some wires but the motor does not try to kill you

Back to your diagram - I'm a belt and braces guy so I would also have beefy connectors - orange bars - between the modules - as well as or in place of the end green ones on each module


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## Ocean (Dec 20, 2016)

OR-Carl said:


> Yeah, I will hopefully not be pulling 300 amps all too often, but it would certainly be needed to get any sort of acceleration on some of the hills I have here. Ocean, was your point that from a longevity standpoint, keeping the amp draw of your maximum load low in relation to your AH rating of your pack is probably a good idea? That is to say, try and keep your max load as close to 1C as possible?
> .


I personally like to treat the batteries as nicely as possible - for me that means keeping the average load on the batteries at about 1C. I know they can and will sustain higher loads... but yes I am thinking about it from a longevity point of view. If I am pulling an average of 100 - 200 amps, I like to have a 100 or 200 amp hour battery if possible.

Those contactors that come in a Volt pack - there are two of them, one controlling the POS and one controlling the NEG connections of the pack. So each carries the full load of the pack in the Volt. Since that pack is running at 360v, and it only takes about 15 - 20kW to move a light car down the road at 55mph on almost level ground, you could estimate that those contacts are carrying about 50 amps on average on level ground... but you can double that or even triple it on hard acceleration or pulling up a hill... so they are rated 120 amps. I would not trust one to carry the full load of my vehicle (Bradley, only about 2500#) since I'm running only 150 volts and I see 100 - 200 average amps on my meter whenever I drive. I think your pickup will pull closer to 150 amps @150 volts when you are cruising on level ground... and double that on acceleration.

Anyways, I have a manually operated 250 amp breaker within arms reach as a backup if I need to break the main power in an emergency.

I will say something about the P&S controller. It is designed to control the main contactor - like a 400 amps contactor - as well as a pre-charge contactor. When the key is turned on and power is supplied to the P&S controller, that controller closes the contacts in sequence (Pre-charge first, then main contactor after about 5 seconds). This way, the main contactor does not make or break the full current (or any current really). The main contactor remains closed while the vehicle is in operation. And, if for some reason the controller got stuck on full power, I would break the power with the manual breaker.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> So, I made this diagram of a hypothetical 3s2p setup to try and make sure I understand:


Excellent diagram 
But that's 3s of modules (not cells), so the whole pack is 2p 3s 7s (or "2p(3s(7s))" for those of us that like brackets for clarity) or 2p21s.



OR-Carl said:


> If I understand the operation of the BMS correctly, it senses when a cell is nearing full charge, and shunts power away from that cell so that the other cells can catch up without overcharging the cell that is at the higher voltage. Does the size of the charger play any role there? In other words, if I am charging at a faster rate, does the BMS shunt more power?


No, charging is not controlled at the cell level - there are no switches (relays or contactors) to shunt charging current, and it would be impractical to have them. Charging is shut off (entirely) when the overall voltage hits some level or the BMS sees that an individual cell group hits some level... then the BMS can "fix" charge imbalance by connecting those little wires through a resistor to slightly discharged the most charged cells. Charging is typically at tens of amps (up to hundreds of amps with extreme fast DC chargers), and the connections within the battery need to handle hundreds of amps during discharge; balancing current are a tiny fraction of that. That balancing can be at the "top" (after completing the charge) or the "bottom" (when the battery has been discharged to nearly zero).


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## MattsAwesomeStuff (Aug 10, 2017)

> No, charging is not controlled at the cell level - there are no switches (relays or contactors) to shunt charging current. [...] Charging is shut off (entirely) when the overall voltage hits some level or the BMS sees that an individual cell group hits some level... then the BMS can "fix" charge imbalance by connecting those little wires through a resistor to slightly discharged the most charged cells.


Ummm... you sure that that's how that happens?

Yes there are no relays or contactors, it's done solid-state with transistors.

I thought that's exactly what a passive BMS does. Passively, anytime, if a specific cell voltage reaches max (usually above a healthy max, like 4.25v), it turns on a load (the shunt) to bleed off the energy. Since there's no way to add energy except during charging, you'd only expect this to happen during charging (or I guess, during early regen)... because it only happens when a cell is above it's max.

Since it's always on, it would be peculiar for cells to somehow get ahead of themselves and imbalance themselves faster than the BMS could compensate. Imbalance is small differences in cell chemistry over long periods of time. Though I suppose if you lost a whole cell in like, a 10p pack so there were suddenly only 9p, you might not be able to bleed the excess fast enough.

I think generally the charger charges to the max bulk voltage and stops (or doesn't, it just stops filling because it's "full" so there's no voltage difference). If some cells get overcharged in that time, oh well, the BMS works as hard as it can to bleed that energy off until the lowest-voltage cell can catch up.

The charger is generally going to be more powerful than the BMS. In non-EV applications, I think the charger is often integrated into the BMS and stands as a gatekeeper to the battery too so the max rate of the BMS and the charger and that you can discharge are the same. My impression is that people talk about needing a "more powerful BMS" when they upgrade, when really they don't, it's just all bundled.

I suppose some EV passive BMS's might flag a warning to the charger system to shut down if they have to trigger any of their shunts. That might be common for EVs with CAN communication and all that, but I don't think it's a rule for BMS's in general.

Active balancers likewise are always running too. I'm not sure if they pull energy from specific high cells, or just the whole series string in general, but they'll fill up the lowest cells with energy from pack until the whole pack is at equal voltage. They'll do that regardless of what voltage is there.

Anyway, I think what Carl is talking about is generally true for smaller non-EV BMS's. Don't take any of that as gospel, I'm only moderately confident in any of it.


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## retrEVnoc (Mar 23, 2019)

Hiya Clackamas Carl, I am working on a 96 S10 conversion as well, mine is a 4x4 extended cab. After de-ICEing in Salem OR last year I'm currently finishing up the conversion in Santa Cruz for the winter/spring. Sounds like i'm further along than you but trust me I still have a long way to go.

I can tell you from experience that once you have removed your fuel tank and exhaust there are spaces that accommodate boxed Model 3 battery modules nicely. Working with the BMS on these modules is still a bit uncharted territory AFAIK, but people (including me) are working on it. If you're a programmer that part may be no biggie for you..


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## dtbaker (Jan 5, 2008)

brian_ said:


> Charging is shut off (entirely) when the overall voltage hits some level or the BMS sees that an individual cell group hits some level... then the BMS can "fix" charge imbalance by connecting those little wires through a resistor to slightly discharged the most charged cells. Charging is typically at tens of amps (up to hundreds of amps with extreme fast DC chargers), and the connections within the battery need to handle hundreds of amps during discharge; balancing current are a tiny fraction of that. That balancing can be at the "top" (after completing the charge) or the "bottom" (when the battery has been discharged to nearly zero).


There are several different approaches I've seen with BMS, and it's important you evaluate the pros/cons of each to determine what path you want to follow in your build. The two questions to answer are:

1. how do you plan to prevent over-charge of any single or set of parallel cells in series within the pack. parallel cells will 'self balance' so you only need to check the groups in series.

2. how do you plan to avoid over-discharge, especially under load?

Most BMS I am aware of can be classified in a couple functional groups:

a. voltage monitoring of either just main pack voltage, OR all series connections, and visual/audio warning.
pros: simple, cheap
cons: just monitoring, not preventing damage

b. monitoring plus signal control to end charge or control/cut load. Gross control at pack voltage level is provided by the charger pre-programmed curve, and usually by the controller on the discharge side. Choice of additional BMS that actually controls charge or load probably determines whether you use top or bottom balancing
pros: better protection if BMS control is at the series level
cons: more wiring, expense, and loss of capacity as imbalance grows with 'drift' at series level with charge cycles over time since you are cutting of either the charge or the load when the first series cell or parallel pack hits the limit. periodic manual inspection and re-balancing is required if the BMS does not have any active shunting/balancing capability during charge cycle.

c. monitoring and shunt balancing at the series level, shunting typically only activated when the cell (or parallel group) hits target voltage during charge, and presumes that charge rate has dropped from ConstantAmp (CA) stage to ConstantVoltage (CV) which is usually just .01C of the single or parallel group. Series must be closely enough top-balanced to start with so that no series connection hits target voltage and attempts to shunt while charge is at CA, which typically exceeds shunt limit.
pros: relatively inexpensive (like the mini-BMS), keeps series in top balance during charge.
cons: does have parasitic drain on each series connection to drive the BMS. failure of any individual unit could result in induced imbalance, or active shunting while still in CA stage could result in failure/fire if shunt currents are exceeded.

so..... I think it boils down to:
- do a good manual top balance initially at the series level
- go with simple charger control of top and controller at the bottom with pack level control
- optionally add visual/audio warning for over/under voltage at series level to indicate when manual check and re-balancing is needed
OR
evaluate more sophisticated BMS pros/cons and cost and decide if you want to go that route... more protection, but at additional cost and complexity.


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## OR-Carl (Oct 6, 2018)

OK, my wife went back to work, and it turns out taking care of a newborn baby pretty much eats up all your time. Who would have thought, right ? So, I have not really gotten anything done yet other than to roll my donor vehicle into the shop, and I picked up an engine hoist for the deICEing.


I have been trying to read the forums and do research, so all hope is not lost. I found that there is a forklift breakers about 30 minutes away, but they are still in the process of moving their business, and did not seem to be wildly enthusiastic about helping me find a motor. They did say that they had some 36 and 48v motors, in 9-12" diameters. They quoted me 300-500$ depending on ... well, factors unspecified. 



I know that I am looking for a series wound DC motor, but it is not clear to me how I distinguish the different types. If I understand correctly, the shunt-wound motors have a constant speed, so a forklift would not use one of those for the traction motor, right? What about separate excited? Will it have extra terminals that makes it easy to spot?



My plan is to go down and take a look at what motors they have, but I would like to go armed with a better idea of what I am looking at (and for). Id like to hear from you all on the following things;



1) I will ask if I can bring a 12v battery to give the motor a spin - as that should tell me that the windings are good, right? If it spins nice and smoothly without a bunch of weird noises, then the bearings and brushes are also probably passable - although should I be figuring on replacing those items either way? 



2) I will want to make sure it has a male shaft, and if it is splined, I would prefer to get some piece of hardware with the mating splines, like a brake if it has one attached to the tailshaft.


3) I am going to need to advance the brushes for higher voltages, right? Is there an easy way to tell if that is going to be easy/hard/impossible on a particular motor?


4) Identify it as actually being series wound - the other types are unsuitable, right?


5) Make sure its going to be good size. It seems that a 9" motor is considered fine for a little around-town pickup, but is there any advantage to a larger motor if the price is right? 



As always, its good to hear from you who have been there and done it. I suspect a lot of this info has been covered in the thread on forklift motors, but if I spend 1 minute reading each post, its going to take 40 hours to slog through it all!


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## dtbaker (Jan 5, 2008)

OR-Carl said:


> ... there is a forklift breakers about 30 minutes away, but they are still in the process of moving their business, and did not seem to be wildly enthusiastic about helping me find a motor. They did say that they had some 36 and 48v motors, in 9-12" diameters. They quoted me 300-500$ depending on ... well, factors unspecified.


I would highly encourage taking a look at a nice NEW Netgain Warp9, shipped to your door with new brushes, advanced for high voltage, with keyed shafts matching many of the existing available clutched and clutchless adaptor designs.

a 9" brushed DC motor, with a 144v or 160v nominal battery pack 'feels' about like a small block V8 in terms of torque, and has a decent max rpm (around 5000 rpm if you want to be safe) enabling use of existing gearing for reasonable starts and reasonable top end for highway speeds.



OR-Carl said:


> 5) Make sure its going to be good size. It seems that a 9" motor is considered fine for a little around-town pickup, but is there any advantage to a larger motor if the price is right?


larger motors, like 11" or 13", do have more torque and higher continuous output capabilities, BUT lower rpm limits. 9" at 144v or 160v is PLENTY for an s-10.


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## brian_ (Feb 7, 2017)

dtbaker said:


> I would highly encourage taking a look at a nice NEW Netgain Warp9, shipped to your door with new brushes, advanced for high voltage, with keyed shafts matching many of the existing available clutched and clutchless adaptor designs.


For only US$2400 (and up).  This is less expensive that any other type of new motor of usable size, but not a trivial expense compared to the salvage approach (for those who can find a motor this way), which is why people salvage them from forklifts.



dtbaker said:


> a 9" brushed DC motor, with a 144v or 160v nominal battery pack 'feels' about like a small block V8 in terms of torque, and has a decent max rpm (around 5000 rpm if you want to be safe) enabling use of existing gearing for reasonable starts and reasonable top end for highway speeds.
> 
> 
> larger motors, like 11" or 13", do have more torque and higher continuous output capabilities, BUT lower rpm limits. 9" at 144v or 160v is PLENTY for an s-10.


Have a look at the WarP 9 specs: the manufacturer only tests it up to 72 volts, which is enough for 41.9 horsepower at 2198 rpm (and much less at lower or higher speeds), and it can't maintain that for long without overheating. Power is higher at higher voltages, but it is not clear how high, since no one seems to test them objectively. 150 kW (200 hp) for a brief period was mentioned earlier - that's roughly half the power of a typical modern small-block V8. Certainly workable for an S-10, and maybe comparable to the stock V6 for brief periods, but not what one would expect from even the 1990's V8's which got swapped into this model of truck. Just tempering expectations...


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## OR-Carl (Oct 6, 2018)

I have made some good progress on the forklift motor thread - it goes faster if you skip over all the people who ask "Will this pump motor with female splines work?" 





dtbaker said:


> larger motors, like 11" or 13", do have more torque and higher continuous output capabilities, BUT lower rpm limits. 9" at 144v or 160v is PLENTY for an s-10.



Yeah, buying something off the shelf has "get it done" appeal, but if I can shave a couple grand off the price of the motor, and up-cycle a motor that might otherwise be scrapped, I figure that its at least worth the ole college try.



I figured that larger diameter should give you more torque, that makes intuitive sense. Likewise the RPM limits being lower makes sense, the bigger you get, the more stress you put on the armature at a given speed. 



I am curious about RPM limiting - Is that something that you handle through the motor controller? Does the motor controller need to know how fast the motor is spinning, or do you just tell it not to exceed a certain voltage (or rather duty cylce, as it is using PWM to chop the pack voltage?) on the motor side? 



Thanks for weighing in, Brian. It seems to me that I will probably be perfectly happy with a 9" motor - I am not really too concerned with getting high performance on my first build. If it moves under its own power I will feel like I have succeeded . I made a spreadsheet based on the equations for rolling friction and air resistance, and using a drag coeff. of .49, frontal area of 2.5m^2 and a rolling resistance of .02 (I have only marginal confidence in these values -anyone have more accurate figures?) I came up with about 20kw to move the truck at 55mph if it weighs about 3500lbs. About 10kw at 40mph, which is likely to be my average speed. So even with big hills, I will probably not exceed 40kw for more than a minute.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> I am curious about RPM limiting - Is that something that you handle through the motor controller? Does the motor controller need to know how fast the motor is spinning, or do you just tell it not to exceed a certain voltage (or rather duty cylce, as it is using PWM to chop the pack voltage?) on the motor side?


A brushed DC motor controller doesn't really need to even be aware of motor speed, and voltage limiting is generally inherent in the component choices: the controller can't put out more voltage than the battery supplies (at 100% PWM duty cycle it's just a closed switch), and the battery is normally chosen to not exceed what the controller and motor can handle.

The limit which is programmed into a controller is typically for current, both to protect the battery from excessive discharge rate and to protect the motor.

If the drivetrain (clutch and transmission) is not in neutral, and the tires are not spinning freely in the air, the motor can't go too fast. Don't mash the pedal in neutral.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> It seems to me that I will probably be perfectly happy with a 9" motor - I am not really too concerned with getting high performance on my first build. If it moves under its own power I will feel like I have succeeded .






OR-Carl said:


> I made a spreadsheet based on the equations for rolling friction and air resistance, and using a drag coeff. of .49, frontal area of 2.5m^2 and a rolling resistance of .02 (I have only marginal confidence in these values -anyone have more accurate figures?) I came up with about 20kw to move the truck at 55mph if it weighs about 3500lbs. About 10kw at 40mph, which is likely to be my average speed. So even with big hills, I will probably not exceed 40kw for more than a minute.


The calculations of power required to overcome drag at a constant speed make sense. CD and A values seem reasonable; I don't know about the rolling resistance one way or the other, but it looks like you have aero and rolling drag about equal at 55 mph. That seems roughly reasonable.

To determine a power requirement for climbing, just add that power for drag to the power to raise the potential energy of the vehicle: vertical speed multiplied by weight, or grade multiplied by road speed multiplied by weight. So to lift two-ton truck up a 6% grade at 65 km/h, it takes 0.06 * 19 m/s * 16 kN, or 18 kW... or 28 kW to maintain 40 mph up that grade. I don't know how long your grades take to climb.


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## OR-Carl (Oct 6, 2018)

brian_ said:


> The limit which is programmed into a controller is typically for current, both to protect the battery from excessive discharge rate and to protect the motor.
> 
> If the drivetrain (clutch and transmission) is not in neutral, and the tires are not spinning freely in the air, the motor can't go too fast. Don't mash the pedal in neutral.



Hey Brian, that is all starting to make sense, I think. I had thought about the danger of mashing the pedal while holding the clutch, but this is a concern in an ICE too (although I suspect the electric motor might spin up to its red-line faster?) At any rate, it should be pretty easy to avoid any disasters of that sort. 



I appreciate the input on hill climbing, I will crunch some numbers, but I suspect 40 or 50kw is probably going to be enough unless I head up into the mountains.


That does remind me of one thought I had - if you roll an EV down a giant hill, do you have to worry about your brakes overheating, since you dont really have any engine braking to speak of?


I need to sit down and think through all the details of what the drivetrain is doing to move the car down the road at various speeds - as I feel like I have an incomplete grasp of how it all works. More questions to follow...


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## brian_ (Feb 7, 2017)

OR-Carl said:


> I had thought about the danger of mashing the pedal while holding the clutch, but this is a concern in an ICE too (although I suspect the electric motor might spin up to its red-line faster?) At any rate, it should be pretty easy to avoid any disasters of that sort.


Yes, over-revving that way (or more commonly on a missed shift, ending in neutral instead of in gear) was a risk before electronic engine management... but now it doesn't matter what you do with the accelerator pedal, the engine won't drive itself faster than redline. Some engines were actually incapable of spinning too fast, because they produced so little power at a speed high enough to be a concern.

An electric motor can inherently spin up very quickly, although the rate of speed increase depends on applied voltage and rotor inertia. Still, I haven't heard of it being a problem... although production EVs don't have a clutch or neutral, and they don't have DC motors anyway so their speed is completely managed by the controller.



OR-Carl said:


> That does remind me of one thought I had - if you roll an EV down a giant hill, do you have to worry about your brakes overheating, since you dont really have any engine braking to speak of?


Right - there is no resistance to turning in the sense of engine braking; the electric equivalent is regenerative braking (running the motor as a generator). Every production EV and most conversions using AC motors include regenerative braking, but it is generally not implemented (and isn't easy) with series DC motors. I don't know what people with these motors do about long grade descents, but I suspect that few conversions with a brushed DC motor ever see a mountain highway.


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## OR-Carl (Oct 6, 2018)

Hey, So I have been trying to clarify in my mind the motor behavior and the different relationships of voltage/RPM and torque/Amps. To think about this, I made a spreadsheet with (what I believe) is a fair approximation of the MPH in various gears on my truck. If I am on the right track, It seems that I could probably run in a single gear, I selected 4th to give me a solid top-end speed (that I will probably never use).












Using those MPH values, I worked out about how much power the motor would need to move the car, and how many amps that would be if I was using the full pack voltage of 144. 



Brian, you earlier wrote that with the tires on the pavement, the motor will not be able to overspeed. In looking at these numbers, I can see that to get to a harmful RPM (5000+ maybe for a 9inch motor?) would require a lot of amps. I know that to drive a large current, you need a high voltage to overcome the resistance (which in the case of a DC motor, is the back EMF being created by the spinning armature). Back EMF is also dependent on armature speed, so as the RPMs increase, so does the electrical resistance, and at some point the battery pack voltage will equal the back EMF, and the motor will be incapable of spinning any faster. Is that correct?


So assuming I have that right, next I am wondering about the amp draw. To move the car at 10MPH would only need 10 amps at 144 volts, but since the controller is using PWM, it is going to simply use a low duty cycle, right? If the amp limit on the controller was set to 200A at 144v as an example, that would be the 100% duty, right? Which is ~29kw. So to provide the 1.47kw needed by the motor at 10mph, It would only need to be providing a 5% duty cycle? If I had an infintely variable transmission, I would maybe expect to see 7.3v to the motor (5% of 144), but in reality I am also going to have to consider the nature of the specific electric motor, right? It needs to provide 500 RPM in order to pull that 1.47kw, so the voltage might in reality be higher than 7.3, with relatively fewer amps being supplied.


Is that more or less correct? I am working on another round of questions... would love to hear any feedback people might have so far.


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## OR-Carl (Oct 6, 2018)

Ok, I finally made some time to work in the shop, and have started pulling stuff out of the engine bay. The guy I bought the truck from had started dismantling it to change the head gasket, and just never got it done. 



My current project is to try and extricate the AC system. I am currently thinking I might try and remove it as a complete loop - has anyone tried this and/or is it a bad idea? I dont want to deal with trailering it again to go have the system pumped out - and I am not even sure if it is still charged. the only part that is still attached to the truck is the "cooling radiator" or whatever it is called. I think that if I remove the intake manifold on the engine, I should be able to get the plastic shroud off that holds that radiator up by the firewall. Then I could just run the whole mess down to a shop that can depressurize it for me. (Is it obvious yet that I am not really sure what I am doing?) I like to pretend like its "learning." 


I think there is going to be a lot of space in this engine compartment once I get it deICEd.


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## MattsAwesomeStuff (Aug 10, 2017)

Brian said:


> Every production EV and most conversions using AC motors include regenerative braking, but it is generally not implemented (and isn't easy) with series DC motors


Just because you don't have regenerative breaking, doesn't mean you don't have electrical breaking.

In forklifts for example, they use "plug breaking", which is slamming the motor into reverse, with a throttle proportional to how much breaking you want to be done.

This spends energy to brake, but it works.

...

There's a third option, I think where you just load the motor electrically but don't try to drive it. This slows the motor (and thus vehicle) down, bleeding off the energy as waste heat, but not as severely so as Plug braking. I think you'd just use a large dummy electrical load.

...

Far as I know, no one bothers to do this, because braking is never an issue.

The amount of engine braking is minimal on a downhill, I suspect. You'd have to be going down a hell of a hill for it to matter.



OR-Carl said:


> Then I could just run the whole mess down to a shop that can depressurize it for me. (Is it obvious yet that I am not really sure what I am doing?) I like to pretend like its "learning."


Q. What's the difference between letting the gas escape on purpose, vs the A/C just being old and having a leak in it over months until it's empty, or it getting depressurized in an accident?

A. Legality.

Refridgerants are nasty for the atmosphere, but, do keep in mind this is at an industrial scale that the laws were written for.

If this were a legitimate concern in a legal sense, there would be an industry where businesses capture the old gas. What you will probably find is that gee, no business that deals with this is interested in even providing that service, they only do it for themselves.

Chicken and egg, where do all the DIYers and home mechanics take their coolants? Nowhere. Because no one does.

You can't vent your coolant on purpose. But I imagine you may discover, as many do, that the coolant leaked out gradually long ago, or you found a hole or crack in the lines somewhere that justifies you not taking it in to be emptied, as it had obviously escaped on its own.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> The amount of engine braking is minimal on a downhill, I suspect. You'd have to be going down a hell of a hill for it to matter.


Do you mean with an actual engine? It doesn't matter around town or in most rural terrain, but sustained significant (over about 5%) grades on mountain highways are where you find the people who just use the service brakes without engine braking... by the smell of their cooking brakes when they are ahead of you. People who try towing trailers in real mountains without engine braking are often alarmed to learn that their ignorance has a price. Since most automatic transmission vehicles (which now means most vehicles) - especially those with tow/haul controls - downshift for added engine braking automatically, I'm sure most drivers don't even realize that they are doing it.

Back when automatic transmissions had no torque converter lockup clutch and crude controls, and cars had brakes that would be unacceptable by today's standards, ordinary families on vacation routinely found themselves by the side of mountain highways waiting for the brakes to cool enough to drive again.



MattsAwesomeStuff said:


> ... where do all the DIYers and home mechanics take their coolants? Nowhere. Because no one does.


Not true - lots of us take used coolant to waste disposal sites; in this area, these are the same places that take used oil. For the once a decade that a typical car needs a coolant change, it's not a lot of hassle.

Many people probably just put it down the drain, and with sufficient dilution in a municipal system, for just the DIY crowd that's not a huge problem.

Irresponsible jerks dump it in storm sewers.


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## MattsAwesomeStuff (Aug 10, 2017)

> Do you mean with an actual engine? It doesn't matter around town or in most rural terrain, but sustained significant (over about 5%) grades on mountain highways are where you find the people who just use the service brakes without engine braking... by the smell of their cooking brakes when they are ahead of you.


I guess it depends how sustained "sustained" is. I've always just pulsed my brakes (building up a higher temperature, thus a higher rate of cooling by having a higher delta T, then let off brakes to let them air cool completely).

But, engines do some breaking on their own (versus, coasting in neutral). I've found that coasting 3 miles down decent downhill in neutral vs. in gear is only about a 10km/hr speed difference, though of course it depends on the grade.

Even when towing I've been skeptical of downshifting unless I feel I really need it. As the mantra goes "Brakepads are cheap and you can fix them yourself, transmissions are not."

Of course, an EV would have to get to the top of that sustained hill first, which, is a moderate issue considering range.



> Not true - lots of us take used coolant to waste disposal sites;


Err... refrigerant. Not coolant. Gas, not antifreeze/water.

I've seen lots of places that supposedly do it, but don't do it whenever you call to ask for it to actually be done. Even the city dumps that supposedly do will have staff give you a weird look and pretend not to know what you're talking about when you go to drop off a fridge. They'll tell you to go somewhere else to do it.



> Many people probably just put it down the drain, and with sufficient dilution in a municipal system


Coolant (antifreeze), in small amounts, often a city fire department will let you drop off household amounts for free. Ditto for motor oil or other random household chemicals you don't want. It being better than dumping it down the drain.

I caught a cleaning company dumping their buckets in the storm drains last year, every week. I approached them and told them they can't dump chemicals into a storm drain, that goes straight to the river. They said "There's no chemicals in here." I said "It's just water?", they said "Just water and cleaners. There's no chemicals." Idiots. I mean, technically water, and air are chemicals, but, even colloquially, cleaning agents are certainly chemicals. Told them to dump it in the toilet. They insisted their boss told them to dump it in the street gutters. I told them clearly they did not, and why would they carry it outdoors rather than dump it in the toilet in the same rooms they were cleaning? Ugh. Some people.


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## OR-Carl (Oct 6, 2018)

Yeah, I suspected that engine braking would have been something that would have come up if it was relevant to EV conversion, but mostly I was just curious. 



I spent some more time today getting the engine bay de-cluttered. I can see how venting the refridgerant would be a tempting way to go, and it seems to me that r-134A is neither that toxic or that harmful to the environment in small quantities (or the EPA wouldnt allow its use as a propellant in canned air, right?). I suspect that I am going to go to a lot of trouble to try and do the right thing, only to find that all the gas has already escaped. I think the whole AC system will come out intact, although the last bolt holding the plastic shroud over the cold side radiator is just spinning. Great. I presume there is a nut somewhere on the other side of the firewall that is turning, or something. 



Removing the intake manifold turned out to be a real bitch of a job. After getting it freed, I realized there is a fuel line or something on the back side that I probably cant get to without taking the AC parts out first. Maybe a crowfoot would have worked... The only solace is that none of this stuff will have to go back in. 



There is a car battery replacement shop locally that has been trying to sell some used OEM battery packs, and I think I am going to try and go pick up their 36kwh tesla/mercedes pack. They just dropped the price to 4500, which seems like a pretty good deal for 12x of the 3kwh ~25v Tesla modules. I want to make sure they will let me take a look inside and measure the voltages of the modules before I buy them.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> But, engines do some breaking on their own (versus, coasting in neutral). I've found that coasting 3 miles down decent downhill in neutral vs. in gear is only about a 10km/hr speed difference, though of course it depends on the grade.


Shift down a gear for more engine speed, and you'll get a lot more braking.



MattsAwesomeStuff said:


> Even when towing I've been skeptical of downshifting unless I feel I really need it. As the mantra goes "Brakepads are cheap and you can fix them yourself, transmissions are not."


Engine braking does zero harm to a transmission. Unlike the brakes, the transmission is not absorbing and dissipating the energy, it's just passing it through mechanically as it always does. The energy is dissipated into the air which is pumped through the engine. Why wear out brake pads and rotors instead of wearing out nothing, and why push the brakes to the edge of unserviceability while driving for no reason?



MattsAwesomeStuff said:


> Err... refrigerant. Not coolant. Gas, not antifreeze/water.


Okay. You said coolant, so I assumed that you were making a comparison to the handling of engine coolant.


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## OR-Carl (Oct 6, 2018)

Okay, the stuck bolt is still attached to my truck, and the plastic housing came out ... in a couple pieces. Lets say it was brittle from age, not that I yanked it out in a fit of rage.












Anyway, as I figured, the whole system came out in one big loop. Not sure if there is any refridgerant left in there, but if so, I can now go get it drained at my convenience. 












The blower motor in this truck is located in the engine compartment, and I now have a little square hole in the firewall where I could mount an electric heater when I get to that stage. I have not decided if I am going to try and pull out the heater core, or just leave it in there.



It is starting to feel like progress is being made, though. I need to finish a few last things before the engine is ready to be hoisted out, and there is still a gas tank and exhaust system to deal with.


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## OR-Carl (Oct 6, 2018)

I forgot to bring my camera to the shop today, but I made a bit more progress. I managed to get the bed lifted off today- it went fairly well, although there was a bit of rust present which made everything harder. They dont salt the roads here, but this truck lived up in Washington for a while, and so it is kinda rusty. I am sort of leaning towards spending a bit of time getting it cleaned up and painted while I have everything torn down. I am maybe looking at new brake lines too, which I have not done before.


I had planned on picking up batteries today, but the seller didnt have a forklift, so they are going to deliver it with a box truck and lift gate. The voltages of the modules were all within .016, and showing 26.4ish volts on average. Its a 36kwh Tesla module from a Mercedes, so 12x 3kwh modules. I think the long and skinny modules will be a great shape for the S-10, as I have 2 long skinny slots on either side of the driveshaft. I might check and see if there is enough room behind the seats to squeeze in my BMS and charger. I was thinking I would pull all the original BMS wires from my 42 cell groups on each side up to a big fuse block. Then my new BMS can monitor the pack from there, and that way I will also have my series strings paralleled at the cell level.


Anyway, lots to think about. I am currently feeling like salvaging a motor is going to be too much to take on right out of the gate. The path is laid out in these forums, but there are a lot of steps, and it seems that the motor-to-transmission coupling is critically important. If I simply buy a standard motor and an off-the-shelf adapter plate with an included hub, It eliminates a lot of unknowns. Part of me wants to really get the full DIY experience and try and make it work, but I suspect I would end up with something looking like it came straight out of a Mad Max movie. 



I have read through the installation manual for the hyper 9, and I am currently leaning in that direction. The controller has more wires to hook up, but It doesnt look really any more complicated to wire up than a ZEVA DC controller. And I like that the controller that comes with the Hyper 9 has a built in serial port, and connects directly to a computer for programming. Anyway, its been a long day. More to follow.


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## MattsAwesomeStuff (Aug 10, 2017)

Do whatever is most fun for you.

I would strongly encourage you not to buy a Hyper9.

If you are concerned about the machining aspects of the coupler and Motor:Transmission interface... just drop both off at a machine shop and tell them to make you one.

It might cost $1000. Who cares. You'll still save buckets of money compared to overpaying for a Hyper9.


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## OR-Carl (Oct 6, 2018)

> just drop both off at a machine shop and tell them to make you one



Hey Matt, this is perhaps a bit oversimplified, but I get your drift. For the right price you can get any job subbed out. It is however not an entirely trivial job that I would be asking to have done, especially if I had a splined motor shaft that needs to have a hub custom fabricated out of scrap pieces of the old machine (assuming you got ahold of said scrap). It would mean finding the right machine shop that had the skill and also the desire to take on such a project. Not impossible, but not trip-to-the-hardware-store easy. 



Did the AC forklift motor you got have a keyed shaft, or is it splined? What route are you planning on going for your coupling, if you havnt gotten there already? 



The coupler really is the part that gives me the most pause, since the spec for runout on the flywheel has to be pretty darn close to not cause expensive problems down the road. I feel like I might be able to make my own adapter plate out of aluminum, but getting everything lined up perfectly still makes me nervous.



Can anyone that has used a CAN-EV adapter plate and hub speak to the level of precision in their work? I am half tempted to get a little dial gauge to check the flywheel runout once it is bolted on - but I am not even sure how to go about determining if the shaft alignment is accurate enough other than spinning it up and listening for weird noises or vibration. I am also not sure yet if my trans has a pilot bearing, and if the CAN-EV hub has taken that into account. 



An off-the-shelf motor has a big upfront cost, but it it should outlive me if properly installed. I say properly installed, because I read the thread about the 11" motor that broke off its shaft because the "machine shop" that mounted it didnt align it properly. I also suspect that an off-the-shelf mounting plate might still have some resale value if I switch vehicles down the road - a custom one-off build might be a harder sell. 



Anyway, not sure yet where I will ultimately land on this - but if I do end up making a good score on local batteries, I will have some room in the budget to take shortcuts with the motor. I find that my expectations at the outset were pretty low, but as I realize what might be possible, I start to get excited about getting just a little bit more... 100 miles of range on a 15k budget seemed unrealistic at first... maybe I am still dreaming


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## jefsmk (Dec 12, 2019)

I'm following this tread closely as I'm in the same situation deciding on the best battery / motor combo for a VW build I'm working on. Don't really understand peoples "hatred" for the Hyper9 motor:



MattsAwesomeStuff said:


> I would strongly encourage you not to buy a Hyper9.
> ...
> It might cost $1000. Who cares. You'll still save buckets of money compared to overpaying for a Hyper9.


Seems that a new DC motor and controller is pushing $3k. Dealing with (and trying to find) a used forklift motor would take that price down to, what, maybe $1500 including the controller?

So assuming I _can_ find a motor with a decent output shaft, the adapter is basically the same price, and the battery situation is the same. So, I could save 1500-2000 going used DC versus new AC with encoder feedback, and modern highly programmable controller. Just not sure the trouble sourcing and implementing a used DC motor is worth it, but also don't want to be wasteful either. So, torn!!

People talk about a salvaged Leaf, but you cannot put that motor on an OEM transmission, and I'm not going to Frankenstein the whole front end into my ride, so that seems like a non-starter.

If only someone sold a AC motor / controller / battery pack for under 5k, this would be soooo easy!!!

Sorry to hijack the tread, carry on!!


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## OR-Carl (Oct 6, 2018)

Hey Jefsmk, I am glad you chimed in! I appreciate your input, getting feedback makes me feel less like I am just ranting to myself 


It does seem like there are a lot of strong opinions out there on what the best motor option is. I can totally get the rationale for feeling like a forklift motor is really the most cost effective option - it does win on price hands down. But I went and looked at the EV album, and just about all the pickup conversions I looked at used off-the-shelf motors. Lots of warp 9s, lots of the ADC 4001's (or whatever they are) some warp 11s... So it seems like from a project completion standpoint is concerned, buying a motor is probably going to cause less hangups. 



Once you start going down the road of buying a new motor - I think the Hyper 9 looks like it is a superior choice to the Warp 9. The only win for the DC system is price (about 1000 bucks) and a bit of simplicity (wire 9 wires in harness, 4 power leads, vs 35 in the harness and 5 power leads) So the way I see it, if you are going to try and save money, go with the forklift motor. If you want to reduce the complexity a bit and streamline your build, you might as well cough up the extra thousand and get an AC system. 


Speaking of batteries, I finally managed to get my hands on that 36kwh Tesla/Mercedes pack.







I paid 4700 for it including delivery to my door. Looks great inside, and the modules were within .016v of each other. The voltage of the 7s modules was about 26.4v, or about 3.77v/cell. It looks like there are some nice contactors in there, although I am not sure yet if their ratings will work out in my build. I am thinking I might try and salvage the coolant manifolds too, and modify them down for my split pack. I was hoping there would be room for 2 single rows of 6 modules on each side of the driveline, but I think it might be too tight. Once I get the pack broken down I will take more measurements and start thinking about how I am going to go about it. I did measure the space behind the seats, and I think there will be room there to mount the BMS and maybe the charger. If I pull off the carpet I can mount stuff directly to the sheet metal that makes up the back of the cab, and maybe get some heat transfer if the charger needs it?





I also finished removing everything off the engine, pulled out the gas tank, fuel lines, exhaust system and removed the driveshaft. There was about 5 gallons of ancient gas in the tank. I am not going to miss having to deal with fuel systems. A friend's dad has a transmission jack, and is going to come out next weekend and help me get the motor and transmission out and on the bench. 



Its starting to feel like I might actually get this thing going. If not, I will just buy a BMS, rewire the batteries for 24v and add them to my off-grid system. It would be about 2 weeks worth of power


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## jefsmk (Dec 12, 2019)

Where did you get a hold of those batteries?


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## OR-Carl (Oct 6, 2018)

Hey Jefsmk, I found a posting on Craigslist by searching for EV batteries. They came from a local shop specializing in hybrid battery repair and replacement. I guess they have contacts who send them batteries from wrecked cars. They had a couple different things available, A leaf pack, one from a volt (for $2000) and some others. Might be worth checking your local CL, and also calling around to see if you can track down something similar in your area. Its probably not a very big market yet, so I bet it would not be too hard to track down someone who knows where the batteries go.


I took a few more pictures of the battery today. Here is the Tesla BMS that sits on each module:









I took off the plug, and it is super easy to see how it is all wired up:











Anyone have any idea how I might identify this connector to get ahold of the mating female end?


I have started working on a wiring diagram, but I realized once I got well into it that I screwed up and made them 6s modules - in reality they are 7s! Oh well, it works to illustrate my point, and hopefully get some questions answered by the experts.











Basically I was thinking of running the pack in 2 strings with 6 modules each. Using those BMS harnesses, I would put all the cells in each string into parallel by joining each cell-level wire in a fuse block. I was then going to run my BMS wiring out of the fuse block. I am currently leaning towards a Dilithium BMS with one satellite - which will also let me use up to 20 of the 24 total thermistors - would there be any issue with them being the right values? 



I feel like I drew something similar up earlier, and i believe Duncan commented about connecting the modules in parallel as well as the cells. In other words, connecting a large orange bar from A1 to A2 and B1 to B2 etc all the way down the pack. Did I understand that correctly? I could see how if one of the strings blew its main fuse, power is going to try and flow over the BMS wires if there are no beefy interconnectors at the module level, and that would blow all 42 fuses in the fuseblock - right? The question becomes is one of those outcomes more desireable? Blow all the fuses and isolate the string, or let it keep its connection and share power with the other string?


I also noticed that Tesla puts a contactor on both positive and negative as they leave the battery box. Is this just to give some added redundancy in case the main contactor fails closed?


Looking at all the wiring that is going to need to happen between the two strings, I am starting to think that in a perfect world I would keep them together in the same battery box. I am going to give some serious consideration to the idea of just re-using the original battery enclosure and plopping it down on the frame where the bed used to sit. I would then build a steel frame out of 1 1/2" square tube that would hold a wooden flatbed high enough to clear the battery box. Would probably raise the bed height by about 8" or so. I do kind of like the idea of a flatbed, especially if I could add some short fold-down sides.


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## OR-Carl (Oct 6, 2018)

I got the battery pack dismantled today. The contactors didnt have an amp rating on them, and I forgot to get the part number, but they are made by Gigavac, and I am guessing they will probably be plenty beefy for my system. I pulled out all the BMS related parts (if anyone is interested in the module level or pack level boards I will be glad to mail them off to you). I have been looking for any info on the vintage of this pack, but have not come up with anything conclusive. I was told it was from 2017, but have no way of knowing - the b200e Mercedes model only ran from 2014-2017, and it seems there were not many of them sold. I did find a little enclosure on the side that contains little dessicant packages which had the date 2/16/18 written on the side. Not sure how often those would have been serviced by the dealership.



The modules are supposedly 42 lbs apiece, so that puts this pack at 500lbs just in modules. I am starting to think I might repurpose the whole box. Its made out of really beefy aluminum plate, and has bolt flanges all the way around. I hung the box up, and it weighs in at a little over 100lbs without the lid. I think I would be hard pressed to make anything as lightweight, tough, and watertight myself, so I am inclined to try and keep it. I think the new BMS will fit inside there, and it will let me keep all the coolant plumbing stock. Looks like they ran all the pipes in a sealed channel at one end, and I think there is a little float switch in there to warn if there is a coolant leak. 












I am thinking the box will mount with a steel subframe, and then doing the rest in wood, sort of like this:











Anyway, tomorrow the engine comes out, so that will feel like a big milestone.


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## OR-Carl (Oct 6, 2018)

Well, the truck is now down to a rolling chassis. With an assistant, it was possible to remove the transmission and engine as one unit. Would definitely have been a PITA without an extra set of hands. Once I got everything unhooked, I weighed the engine (250#) and the intake, exhaust, starter, alternator, etc and came up with about 325lbs (without fluids) coming out of the front of the truck. With the AC, radiator, fluids, and power steering pump, lets say 400# of weight loss total. 



Out of the back end I removed the gas tank, muffler, misc brackets, spare tire and the bed - lets say 300lbs, plus nearly 100lbs of gasoline with a full tank. 



What I am driving at is, do I need to be concerned about weight distribution if I put that battery box where the bed used to be? I figure I will put 200# back into the engine bay easily, and the batteries should come in at about about 650# with the box and mounting rails. I am getting a lot of comments that the truck is not going to handle right if I move too much weight around - and I would like to hear peoples opinions about this. I have driven trucks with large loads in the bed, and have never felt like the handling was in any way compromised. If one drives pretty conservatively, how much weight shifting would have to happen to make the truck handling unsafe?


Well, the next step is to start getting some parts ordered, I think. I have decided I am going to go the off-the-shelf route, and order a standard mounting plate and a motor that mates to the standard coupler that comes with the kit. As I understand it, when I move the flywheel over to the new hub, I will want to make sure that the "magic distance" is exactly the same, right?











Is this the right idea? I might try and find a more dependable straight edge, but the distance marked in red is what I am going to try and replicate, right? I also ordered a dial indicator, and I am going to check the runout on the flywheel and try and make sure I get it well aligned when I move it over.


Would love to hear some feedback, I sometimes feel like I am just writing to myself


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## MattsAwesomeStuff (Aug 10, 2017)

> If one drives pretty conservatively, how much weight shifting would have to happen to make the truck handling unsafe?


I don't have an answer, but I read somewhere (maybe here) that typical weight distribution for pickup trucks is like 70:30, because other than passengers, all the weight you add goes on the back so, the back has to start fairly light (also the engine is up front).

A half ton is 1000 lbs. Say 200lbs for the driver. That means you can load 800lbs on the bed, and, it should still handle just fine.

You're putting 650 lbs on the rear just in batteries alone.

You've lightened the back by, I dunno, 100lbs? 150lbs? (gas and exhaust)

So you're still adding 500lbs to it.

Luckily you're not lightening up the front end much at all by putting the motor and some batteries back there, so, net result is basically that you've added 500lbs to back of the truck.

That's 3-ish people on the bed.

So, to know what it would feel like, it's going to feel like even when empty, you've got 3 adults laying on the bed. Your suspension will have dropped as much as that would drop it, your handling will be affected as much as your handling would be affected by it.

You've also turned a 1/2 ton into a 1/4 ton, with a 500lb max. If you count your weight, now only 300lb max cargo in the bed. That's pretty laughable.

Trucks seem to be pretty consistently overloaded in use compared to their specs. Hell, an extended cab with a work crew in it is already maxed out for weight, without even putting anything in the bed.

Anyway, your analog seems to be, you've loaded 500lbs in the bed compared to a normal S-10, nice and low.



> I have decided I am going to go the off-the-shelf route, and order a standard mounting plate and a motor that mates to the standard coupler that comes with the kit.


I think you'll regret this. I think you're afraid of a small amount of machining work that you could just pay a machine shop to do to end up with something much superior for much less. But, broken records and all, if you're more comfortable with a kit, then stay in your safety zone. There's no wrong answer.



> Would love to hear some feedback, I sometimes feel like I am just writing to myself


You're doing a great job documenting. Sometimes that can set people back into "reader" mode instead of "participant" mode.

Your thread has 2700 views right now, and 69 posts. So, worst-case scenario, if everyone reads every time you post, you've got at least 40 people reading this. Probably more, as people will catch up the last half-dozen posts.


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## brian_ (Feb 7, 2017)

OR-Carl said:


> What I am driving at is, do I need to be concerned about weight distribution if I put that battery box where the bed used to be? I figure I will put 200# back into the engine bay easily, and the batteries should come in at about about 650# with the box and mounting rails. I am getting a lot of comments that the truck is not going to handle right if I move too much weight around - and I would like to hear peoples opinions about this. I have driven trucks with large loads in the bed, and have never felt like the handling was in any way compromised. If one drives pretty conservatively, how much weight shifting would have to happen to make the truck handling unsafe?


The most straightforward answer would be that the truck can handle the axle loading that the manufacturer intended.



MattsAwesomeStuff said:


> I don't have an answer, but I read somewhere (maybe here) that typical weight distribution for pickup trucks is like 70:30, because other than passengers, all the weight you add goes on the back so, the back has to start fairly light (also the engine is up front).


No modern empty pickup truck is as front-biased as 70:30, but they do start front-heavy, for those reasons.



MattsAwesomeStuff said:


> A half ton is 1000 lbs. Say 200lbs for the driver. That means you can load 800lbs on the bed, and, it should still handle just fine.


Not really. An assumption in the design of a pickup is that some load will be carried in the cab. Also "half-ton" is a very rough approximation - the actual payload capacity of a truck called a "half-ton" may be much higher or even lower than 1,000 pounds.


Have a look at the axle weight capacities (GAWR, front and rear). The rear will normally be higher than the front, indicating that the truck can be loaded rear-heavy and still function safely. You'll also notice that the total of GAWR-rear plus GAWR-front is more than the total Gross Vehicle Weight Rating (GVWR), so you can't load the front axle to the limit if the rear axle is at the limit... so the truck can end up quite rear-heavy.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> Anyway, your analog seems to be, you've loaded 500lbs in the bed compared to a normal S-10, nice and low.


It's low compared to a normal cargo load, but sitting up there on top of the frame, above stock cargo bed height, is not very low in the truck. It would be nice to be able to mount the battery lower, between the frame rails; that was often done with lead-acid setups, but can be difficult with the rigid size and shape of available EV battery modules.


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## OR-Carl (Oct 6, 2018)

Hey Brian, thanks for pointing me in the right direction. I found the weight ratings for my pickup, and did some back-of-the envelope math. I am over simplifying it, since any weight added between the axles is going to be shared front and back depending on its position (if I am remembering my high school physics). I am assuming that any weight behind some imaginary midpoint is only resting on the rear axle and vice versa. 



Gross Axle Wt Rating - Front (lbs): 2500
Gross Axle Wt Rating - Rear (lbs):2300
limited by spring rating: axle is rated for 2900

Gross Vehicle Weight Rating Cap (lbs):4200

Stock config:
Curb Weight - Front (lbs): 1757
Curb Weight - Rear (lbs): 1313
Curb Weight - Total(lbs): 3070
Front %: 57%
Rear %: 43%
Rear axle remaining capacity: 987

Loaded to the max rating of the rear axle:

Curb Weight - Front (lbs): 1757
Curb Weight - Rear (lbs): 2300
Curb Weight - Total(lbs): 4057
Front %: 43%
Rear %: 57%
Rear axle remaining capacity: 0


Post conversion unloaded:
Curb Weight - Front (lbs): 1757-400 + 200 = 1557
Curb Weight - Rear (lbs): 1313-400 + 800 = 1713
Curb Weight - Total(lbs): 3270
Front %: 48%
Rear %: 52%
Rear axle remaining capacity: 587
Total cargo capacity remaining: ~1000lbs


Curb Weight - Front (lbs): 1557
Curb Weight - Rear (lbs): 2300
Curb Weight - Total(lbs): 3857
Front %: 40%
Rear %: 60%
Rear axle remaining capacity: 0


What I am seeing is that after the conversion, with me in the cab, I will probably be looking at pretty close to 50-50 weight distribution. If I put 600lbs of cargo on the back, which is going to be all I can put on those rear springs, I would be closer to 40-60. That is a little bit more back heavy than a fully loaded stock truck, which would be 43-57. 



So yeah, My truck should probably be limited to 400-500lbs of cargo... Still, you can make a lot of concrete with 5 sacks of portland cement, as long as you bring in the sand and aggregate with a big gas guzzling truck 


Anyway, I rolled the chassis out today and got most of the grease and oil out of the engine bay.










I also took all the measurements for the motor mount, hub, and pilot bearing. Its starting to sound like the motor I want might be back-ordered until June, but that might not be a terrible thing. If I get too carried away I am probably going to rush and cut corners. I am finding a lot of little things that should get fixed on the chassis. I am probably going to spend some hours getting the rust off the frame so I can get some paint on it. I am probably going to want to put new brake hoses on it, but luckily the lines seem to all be OK. I should at least check out all the brake pads, too. The rear differential cover is rusted pretty bad, and there is a broken off bolt that I will need to do something about. I am also going to try and track down a manual steering box, since dealing with power steering sounds like a hassle. I never parallel park, and need more exercise anyway 


Once all that is squared, I can also work on the battery mounting, flatbed, DC-DC system, brake booster, rough wiring... Yeah, maybe June is ambitious, even!


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## brian_ (Feb 7, 2017)

It looks like you have a good handle on the axle loading situation, Carl. 



OR-Carl said:


> I am over simplifying it, since any weight added between the axles is going to be shared front and back depending on its position (if I am remembering my high school physics). I am assuming that any weight behind some imaginary midpoint is only resting on the rear axle and vice versa


You can fix that oversimplification relatively easily. Yes, the structure of the vehicle is a lever or beam, so the contribution to axle loads of any weight added to it is proportioned between the axles. If something is distance 'x' ahead of the _rear_ axle, and the wheelbase is 'W', then it adds x/W times its weight to the _front_ axle. For instance

at the rear axle, x=0, so x/W=0%, and the weight goes 0% to the front axle and 100% to the rear
at the front axle, x=W, so x/W=100%, and the weight goes 100% to the front axle and 0% to the rear
if the driver is 1.6 m (63") from the rear axle in a 2.995 m (117.9 in) wheelbase (assuming regular cab long bed), then x/W= 53%, and the weight goes 53% to the front axle and 47% to the rear
if a box of battery is in the front of the cargo bed, centered 0.5 m (20") ahead of the axle, then x/W= 17%, and so the weight goes 17% to the front axle and 83% to the rear axle

It's easiest to use a spreadsheet to total up the contributions of the base truck, removed components (negative), added components, people, and cargo. Most DIY builders don't seem to go to even this basic extent of planning, just hoping it will work out okay.


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## OR-Carl (Oct 6, 2018)

Well, I guess my timing for building an electric truck was not great.


I have been busy this last month getting a big vegetable garden going instead of working on my truck. I had planned on taking a break from gardening to work on projects this year, but here we are.


I thought I would go ahead and post about what few things I have done, as I have not completely stopped working on it. Hopefully I can manage to get some good progress made on it during rainy spells, and get things prepared for a final build this summer. 



I did manage to find a manual steering box for it, and I have that installed now. I am a little worried that the extra turn the wheel can now do in each direction is going to break my clockspring. Is this something that has happened to anyone here with a manual swap? Being a '96 it has an airbag in the steering column, and if I can keep that functional that would be ideal.


I also plugged the 12 volt battery back in and thought it would be a good idea to strip out all the "unnecessary" wires from the wiring harness. I am not so sure that was a good idea, but I will never get them all back in, so I will have to live with it. This model year runs the wiring from the transmission into the ECM, and then out to the speedo and the ABS system, so I am probably going to have to keep its brain in there. I was able to get a flicker of life on the speedometer using a drill to spin up the transmission, so that seems promising, but the ABS light stays on when I give it 12v power. It might just be that the sensors are shot, as the front wheels are pretty corroded. I am not going to be too upset if the ABS never works again, but I might try and track down the issue at some point. The dash also told me to check the engine, but it was right where I had left it, so I will have to disable that indicator 


I have also spent a lot of time with a wire wheel trying to remove as much rust from the frame as possible, and I am about ready to call it "good enough." You could probably spend a lifetime on that task and never actually be 100% done. I am using some sort of spray-on goop that says it removes rust, but it really wants you to soak the item for 24 hours to be effective. I am going to give it one more pass with some steel wool and spraying that stuff on, and then paint over whatever is left. 



Also, I checked on my batteries today. 11 of 12 modules had dropped by .1v - down to 26.30. My multimeter only reads 2 decimals, but all of those were reading the same. The final module had dropped quite a bit more, and was down to 26.08. It was also the one that had the highest internal resistance when they were checked out by the guy who sold them to me, so I wonder if that module is a bit weak. I have been sort of thinking I might nix the idea of a new motor and start looking for a dead forklift, as the current world situation has a "recessiony" vibe to it, and saving a few grand suddenly doesnt sound like such a bad idea. If I do go that route, dropping 2 modules off might make sense anyway to put a little less voltage through a DC motor. I know Duncan runs like 300 volts through his, but the dubious device is not exactly a daily driver, right? What do people think is a good upper bound to be conservative? If I did 5s modules, my pack would be 133v at 3.8v/cell. I would not mind having 2 extra modules, and would probably think about using them for my off-grid shop. 



Anyway, I hope everyone is staying healthy, and uses their time in quarantine to think about exciting new conversion projects!


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## Duncan (Dec 8, 2008)

Hi
The usual voltage that people use is about 150v - mainly because of the controllers!

When I dropped down to 130v (messing with Headway cells) it massively limited my rpm's 
I maxed out at 60 mph - as in that was as fast as it would go

At 144v nominal it was fine - but 130v was a pain

300v may be OTT - but the motor only sees the 300v at very high current and high rpm - for road use I have a throttle de-rate that limits me to 500 amps and at the maximum speed limit in NZ I draw about 200 amps and 130 volts
I can boot it then - and it goes very well - but I'm already above the speed limit

If I flick the throttle de-rate off it spins the road tyres too easily


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## OR-Carl (Oct 6, 2018)

I am starting to feel caught up in the garden, so I decided to sink some more time into my project. Here was the rear frame before I got started:










Here it is after spending a lot of time with a wire wheel and scrubbing on some sort of rust remover












I have decided I do not like removing rust. Next I slapped on some thick black chassis paint, and I decided that I do not like painting either  













Its looking better, though, so I am glad that I decided to put in some time on it. Not sure if the rust is going to just flake that paint right off, but hopefully I have bought myself some time. The main point of this project for me was to learn new things, and on that topic I feel like I am doing pretty well. I did look at the rear brake pads, which are getting pretty close to needing to be replaced, but I might defer that until after the truck actually moves. 



Before I launch into the conversion, I want to try and wrap up a few things on the restoration. The front brake lines are pretty rusty, so I am going to give them a quick clean and coat of paint. I also plan on pulling the front wheels off to check the front brakes, and seeing if I can get any signs of life from the ABS sensors. After that I will probably try and get the brake booster installed, and start working on the battery enclosure.


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## OR-Carl (Oct 6, 2018)

Slow progress, but I am moving in the right direction! The front brake pads are also just a hair over 1/8" so they will need to be replaced soon after I get it rolling. Both ABS sensors produced voltage when they were spun up, so I think that system might be okay. The front suspension (A-arms?) look pretty crusty, and all the rubber is cracked and rotten looking, so I am thinking I might overhaul all of that at some point.

I crawled under the cab and got the frame cleaned and repainted underneath, and did the same with all the frame parts that I could get to in the engine bay. The brake lines all got hit with the wire brush and painted, and they are all looking good now. I was worried that they had rusted out, but it was very superficial. I pulled out the wiring from the fuel pump, and have gotten most of the 12v wiring encased in split loom, and out of my way. I had to order the little clips that hold the loom to the frame, and the shipping times have gotten crazy. I guess free 2-day shipping is maybe too good to be true.

The old battery that came with the truck is somehow taking a charge, so I have been working on getting all the safety systems back in order. I now have all the lights working, I have a horn, wipers, and a really annoying warning buzzer. at least I wont leave the lights on. I dont think the ECM likes what I have done to its precious engine, but I did find the wire that controls the Service Engine Soon light and snipped it. Might try and wire it into something else, brush wear indicators, maybe?

I am pretty sure the airbag system still works, but it is all unhooked while I am working on the wiring. One of the crash sensors just came off in my hand when I went to connect the wires today, so thats going to need to be fixed. The ABS probably needs to be plugged into the transmission to be happy, but I am cautiously optimistic that it will work when I get everything put back together.

Next step is to trace a switched hot wire from the fuse box, and use it to run my EV 12v accessories. I am going to try and get the brake booster installed and tested next - a new check valve should be here on Monday.


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## OR-Carl (Oct 6, 2018)

I spent most of this morning running errands to get some parts tracked down, so I did not get much done today. I did take a picture of the engine bay, and it is starting to look a bit more orderly.










Most of the wiring is cleaned up now; all that is left to do on the 12v system is the DC-DC converter, the coolant pump and vacuum pump. I guess there will also be a few 12v connections to run the charger, bms, and motor controller. I also kind of destroyed the blower fan housing, so that is going to need to be dealt with at some point, along with some sort of heater. I will probably just leave room to cram something in down the road, as I don't really want to get too bogged down on that right now.


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## OR-Carl (Oct 6, 2018)

I got the brake booster pump installed today:










I bought this as a kit from EV West, and honestly, I am a little disappointed in the quality. The relay outright does not work, and the pump just runs non-stop. It does pull vacuum, my booster holds vacuum, and the pressure switch opens when it gets down to pressure. The way they have you wire it in the instructions seems weird to me, so I think I am going to get a higher quality relay and try to work out a better method.

I am a little curious about whether you all have added an additional vacuum reservoir, or a gauge of some sort as an added safety precaution? The booster drum itself seems like it only gives me like one pedal push, which I suppose is all you get when your gas engine dies on you.

I have been thinking a little bit about my battery heating/cooling system, and I think I am going to try to reuse the trucks radiator, even though its probably overkill in terms of heat dissipation. I am thinking of plumbing the radiator to a 1" iron pipe T and a maybe 18" section of pipe to mount a 220v water heater element in the coolant loop. Id then have a temperature relay controller that could close a contactor to apply pack voltage when the coolant temperature was below its ideal temp. I am thinking the coolant pump will always run, which will cool the batteries down if they need it. What is the optimum temperature range for the Panasonic 18650s, and how touchy are they about being charged cold?


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## OR-Carl (Oct 6, 2018)

Well I did that thing that I have been trying to avoid: when you go to work in the shop but instead of doing the small project that you probably have time for, you launch into something else, and suddenly find you have made a real mess (and you should probably have labeled all those little piles of screws). 

Well, I did get the heater core out, so that is something. I had been waffling on whether I should just leave it in there, but now that I have it out, I am wondering if it might be big enough to act as the cooling radiator for my battery bank. What do people think? Could the power dissipated by the batteries be estimated by the formula P=I^2 * R? If my modules have a resistance of .006 ohms, and I am going to pull at most 200A continuously (since I have 2 strings, each module will only supply half that), that would be 60W per module at 100A, times 12 is like 720 watts, which is almost 2500 BTUs/hr. Could a little radiator like this dump enough heat to keep my battery temp reasonable? I was thinking it could be mounted up front behind some sort of louvered vent, so I could use the vehicle motion to force cooling air through it, or shut that off if I want to heat my batteries when it is cold out. 








The inside of the truck is now a mess, but I think I have freed up enough space to move the blower fan into the cab. 








The yellow outline is where the heater core duct used to connect, so I think I will move the blower into that space, and leave room for some ceramic heater elements down the road. I am going to ditch all the vacuum actuated vent louvres, and just try and make a physical connection to the one that switches between the defogger (orange) and the dash vents (red). If I pull out the old control knobs, and the clunky old cassette deck, I should free up a nice big section to fill with switches and dials and maybe a little tablet to interface with all the modern stuff. I saw that Zeva makes a little clamp-on meter that lets you tie into the tach and the fuel gauge to give you an intuitive at-a-glance idea of how much power is being drawn. Seems like a cool idea.


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## MattsAwesomeStuff (Aug 10, 2017)

OR-Carl said:


> I bought this as a kit from EV West, and honestly, I am a little disappointed in the quality. The relay outright does not work, and the pump just runs non-stop.


Hmm, EV West has been shitting the bed lately it seems.

There's a chance you've installed it incorrectly.

The kit specifically says it should only run when required. Perhaps you have a vacuum leak which is why it's always required?



> I am a little curious about whether you all have added an additional vacuum reservoir, or a gauge of some sort as an added safety precaution? The booster drum itself seems like it only gives me like one pedal push, which I suppose is all you get when your gas engine dies on you.


A reservoir is common, and easy and cheap to make. Often just a chunk of 4" PVC with end caps, and then a T-fitting installed to run a line to it.

I don't know about modern EVs, but I recall back in the day many people commenting that the vacuum pump was the noisiest part of the vehicle, and annoying to listen to.



> What is the optimum temperature range for the Panasonic 18650s, and how touchy are they about being charged cold?


Not sure about optimum, but it's LiFes that are sensitive to cold charging. I don't think normal lithiums are as much of a problem.



> times 12 is like 720 watts, which is almost 2500 BTUs/hr. Could a little radiator like this dump enough heat to keep my battery temp reasonable?


A typical space heater is 1800 watts. Look at the surface area on it. You'd need half that. You've probably got 6x that.

Conversely, consider that gas engines are like 20% efficient, meaning for every horsepower to the wheels, there's 4x that much horsepower needing to be bled off as heat. If it takes 20hp to maintain highway speed, that's 80hp of waste heat. That's 60,000 watts. A hundred times what you've got. 

That goes into the radiator, but the radiator is sized for kind of worst case scenario, hard hill climbing and acceleration at high speeds. I wouldn't doubt if the average rad could sustain 100hp to the wheels, so 300,000 watts waste heat. Hence the surface area and the fan.

I'd say that when you consider the volume and surface area of the batteries themselves, you will not need a cooler. They will cool themselves.

A cooler is needed during fast charging generally, IIRC, or on very small battery packs that are getting pushed to their limits.


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## OR-Carl (Oct 6, 2018)

Yeah, as I thought more about the vacuum pump, it occurred to me that the way it is plumbed assumes that the pump itself is acting as a check valve. I said the pump always runs, but that is not quite true, it does stop for an instant, and then it cycles on again. If the pump itself is not able to hold vacuum, then once it shuts off, the hose will re-pressurize up to the brake booster check valve and the switch will turn it on again. I am going to try putting a check valve in the line right after the pump, and that way I can also add a T to run hose to a reservoir. 

I am not sure which Panasonic 18650s were used in my modules, but I found some charging data for just a randomly selected (~2500mA) model that said charge temps should be kept within the range of 10 to 45 C 
https://industrial.panasonic.com/cdbs/www-data/pdf/ACA4000/ACA4000PE4.pdf

I suppose you are right that with the surface area of the pack itself, and my modest demands, they are probably not going to readily overheat. Still, circulating some coolant seems like pretty cheap insurance, and should help keep the battery pack temperature even.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> Not sure about optimum, but it's LiFes that are sensitive to cold charging. I don't think normal lithiums are as much of a problem.


Production EVs with other lithium chemistries have battery heating for use in cold areas, including Tesla models, so I wouldn't assume that charging when cold is not an issue.



MattsAwesomeStuff said:


> A typical space heater is 1800 watts. Look at the surface area on it. You'd need half that. You've probably got 6x that.


You can't reasonably compare the surface area of a heater and of a radiator. Heat transfer rate depends on the temperature difference between the sink (air) and the source (heater, radiator...) and the coolant in this case is not nearly as hot as an electric heater element.



MattsAwesomeStuff said:


> Conversely, consider that gas engines are like 20% efficient, meaning for every horsepower to the wheels, there's 4x that much horsepower needing to be bled off as heat. If it takes 20hp to maintain highway speed, that's 80hp of waste heat. That's 60,000 watts. A hundred times what you've got.
> 
> That goes into the radiator, but the radiator is sized for kind of worst case scenario, hard hill climbing and acceleration at high speeds. I wouldn't doubt if the average rad could sustain 100hp to the wheels, so 300,000 watts waste heat. Hence the surface area and the fan.


Modern engine efficiency runs up to 41% efficient, but this logic is good... except that you are ignoring the exhaust, which is where roughly half or more of the waste heat goes. Ideally (if there were no heat transfer to the cylinder walls and head) all of the waste heat would be in the exhaust.



MattsAwesomeStuff said:


> I'd say that when you consider the volume and surface area of the batteries themselves, you will not need a cooler. They will cool themselves.
> 
> A cooler is needed during fast charging generally, IIRC, or on very small battery packs that are getting pushed to their limits.


Sure... except that the only recent EV (not hybrid) sold in mass quantities without active cooling is the Leaf, which can charge at 50 kW like other moderately priced EVs; everyone else finds cooling (even if only forced air like the Outlander PHEV) to be worth the cost, weight, and complication. 

Fast DC charging is an extreme case of battery heating, because it causes a high rate of heat generation for an extended period. Driving the car can easily use more power than fast charging, but only for brief periods of acceleration or grade climbing.

The operating scenario which drives most EVs to liquid cooling, other than fast charging, is probably ordinary driving in hot weather with the air conditioner running.


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## Duncan (Dec 8, 2008)

brian_ said:


> The operating scenario which drives most EVs to liquid cooling, other than fast charging, is probably ordinary driving in hot weather with the air conditioner running.


The real reason is cell temperature equalisation
Leafs have shorter lives - but its just some cells that fail - I suspect it's the warmer cells that fail first - a cell that is warmer will also tend to get more heat dumped into it

Liquid cooling is much more about temperature equalisation than about actually cooling or heating EXCEPT in the extremes


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## MattsAwesomeStuff (Aug 10, 2017)

brian_ said:


> Production EVs with other lithium chemistries have battery heating for use in cold areas, including Tesla models, so I wouldn't assume that charging when cold is not an issue.


Heating batteries lets you get more range out of them in the cold.

Heating during charging is probably convenient just so that when you go to use the vehicle, the batteries are warmed up.

You're right that it doesn't rule out their need, but the fact that cars have battery heaters doesn't necessarily indicate it's needed for charging either.



> Heat transfer rate depends on the temperature difference


Well, okay, I think it's still in the ballpark if you consider how much heat is coming off. Or compare to a water/glycol-based baseboard heater I guess is a better comparison, for hot liquid surface areas. It's just harder to guess wattage on them other than feeling the heat coming off with your hands.



> you are ignoring the exhaust


Err, oops. I meant to fraction that up accordingly.



> Sure... except that the only recent EV (not hybrid) sold in mass quantities without active cooling is the Leaf


And the Leaf isn't great for battery life.

But if you ever need it, to avoid customer complaints about some fringe situation, that's not distinguishable from needing it regularly.

A Leaf shows you yeah, it's certainly technologically possible, and not necessary. Gives credence to it being a nice-to-have feature, not a mandatory one.

If a battery is plumbed for heating or cooling, it's a trivial addition to let it do both.

... I wouldn't say there's a strong case either way.


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## OR-Carl (Oct 6, 2018)

Spent a bit too much time on this little side project - but the baby has not been sleeping well, and problem solving while sleep-deprived goes kind of slow. It has been hard to only have a few hours each morning to get work done, but I am chipping away at it. I decided to scrap the vacuum system that runs all the vents in the dash. I really only need the window defogger, but by keeping one flap operable, I could also keep the dash vents. 



















The shifter levers are off an old Schwinn 10 speed that got hacked up for parts long ago. I am thinking of using the other cable to open an air vent up front that would block airflow to my battery coolant radiator. 

I am going to make some mounting points on the plastic intake opening out of angle iron, that way I can easily affix a heater and some 12v fans later on. I have freed up a lot of room under the dash by taking out all the extraneous ducting.

I have basically stripped this truck down as far as it will go, and I am excited to be able to start actually building it back up again.


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## M640 (Nov 25, 2016)

I have a '92 S-10 "eS10". Standard bed, 5 spd, 144v system. Started as an online kit. I upgraded to lithium recently.

FB1-4001 motor
Curtis 1231 controller
TSM2500 charger, basic EVCC
No clutch
54 Nissan leaf modules, 18S 3P
147.6v max, 192ah
On paper approx a 28K pack

My range is 50 miles to approx 85% discharge. Someone else calc'd it's usage at 459kw/mile. It lost 1000 lbs in the upgrade from lead to lithium. Since the "bones" are there, I can simply add batteries for more range. If you can do it go lithium from the start. Lead is to much of a power drain.


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## dtbaker (Jan 5, 2008)

OR-Carl said:


> I got the brake booster pump installed today:
> 
> 
> 
> ...


the more connections you have, the more likely you will have a vaccuum leak. You should have a check valve close to the brake booster, upstream of all the other connections and to prevent backflow thru the vac pump itself when its not running.

In the swift I used a big mechanical switch, gauge, reservoir, and got two or three brake pumps before vaccuum pump came on. eMiata I used a tranducer, SS relay and no reservoir; works just fine, comes on after every touch of the brakes, but so what, the vac pump pulls enough vaccuum to refresh the booster between braking.

http://envirokarma.org/ev2_mx5e/gallery/121023_vac_done.htm


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## dtbaker (Jan 5, 2008)

OR-Carl said:


> Yeah, as I thought more about the vacuum pump, it occurred to me that the way it is plumbed assumes that the pump itself is acting as a check valve. I said the pump always runs, but that is not quite true, it does stop for an instant, and then it cycles on again. If the pump itself is not able to hold vacuum, then once it shuts off, the hose will re-pressurize up to the brake booster check valve and the switch will turn it on again. I am going to try putting a check valve in the line right after the pump, and that way I can also add a T to run hose to a reservoir.


check valve should be close to brake booster as possible.




OR-Carl said:


> ...
> I suppose you are right that with the surface area of the pack itself, and my modest demands, they are probably not going to readily overheat. Still, circulating some coolant seems like pretty cheap insurance, and should help keep the battery pack temperature even.


living in OR, with moderate temps, and not drag racing with extended acceleration events, I seriously doubt you will need any battery pack cooling. circulating fluids around electricity and that many connections introduces too many negative possibilities.... I would highly recommend you don't worry about battery pack temperature control if you want to keep things simple.


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## OR-Carl (Oct 6, 2018)

Hey Twiin, I am putting a lithium pack in my truck, but I have a long ways to go before I get any mileage data to share! Between growing a big vegetable garden, helping look after my 7 month old daughter, and doing all the other work that needs to happen on a big piece of rural property, I am starting to think it is going to be another year or so before I finish...


I have not had a chance to revisit the vacuum system, dtbaker, but I did finally get the check valves I ordered. There is already a check valve on the brake booster drum, and it does indeed hold vacuum. The problem is that the vacuum hoses re-fill with air when the pump stops. Since the sensor that is supposed to control the pump is in the hose and not measuring the booster drum directly, the system just runs and runs. My hope is that putting a check valve in the short section of hose will keep the hoses at vacuum, and thereby make the switch work correctly.


And you might be right about not needing cooling, but the tesla engineers have already done the hard work for me. The battery box is cleverly designed, with all the plumbing isolated from the modules behind a water-tight bulkhead. I am hoping it will be pretty simple to plumb in a pump and a little radiator. From what I understand, the Leaf is the only production EV that doesnt use liquid cooling, and it is also the one with the most capacity loss. I cant help but imagine that there is a correlation there.


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## dtbaker (Jan 5, 2008)

OR-Carl said:


> ... Since the sensor that is supposed to control the pump is in the hose and not measuring the booster drum directly,


the sensor for your pump MUST be on the vaccuum side of a check valve.


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## M640 (Nov 25, 2016)

Luckily for me someone else already did the conversion and I bought the truck turnkey. My work so far has been converting to lithium.


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## M640 (Nov 25, 2016)

I noticed on my S-10 that whenever I have any of the climate controls on, for example the heat, that the vacuum pump runs continuously. I know that on some GM's that the vacuum helps assist with the ducting and I'm guessing maybe there's a leak in my climate control system somewhere. When I turn the climate controls off the pump only runs for about 10 seconds at a time with a longer off time.


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## M640 (Nov 25, 2016)

I noticed on my S-10 that whenever I have any of the climate controls on, for example the heat, that the vacuum pump runs continuously. I know that on some GM's that the vacuum helps assist with the ducting and I'm guessing maybe there's a leak in my climate control system somewhere. When I turn the climate controls off the pump only runs for about 10 seconds at a time with a longer off time.


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## OR-Carl (Oct 6, 2018)

Have not had time to dig into the vacuum system yet - but have made a little progress in the cab. Getting the dash in and out is a real chore, but now I am hoping it will be in to stay. I tracked down a switched hot wire that goes to the radio compartment, and I am going to use that circuit to power up all my EV systems. I greatly under-estimated the work involved in dealing with rust. Anyway, hopefully this is the last of it for a while...










I did get the accelerator pedal mounted, and ran the wires up into the engine bay today too. Progress is slow, but at least its progress, right?


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## OR-Carl (Oct 6, 2018)

I have not died of covid yet, but I did take on a bunch of projects this spring that made it hard to get to the shop and work on the truck. I am starting to feel like I am on top of things, so time to keep chipping away...









I built a plate that mounts into the radio slot to hold my switches today.








I mounted the SOC monitor, the main power switch, and switches for heater, profile selection, and one extra switch. 

I have a little circuit board that will control the thermostat for the coolant heater, but I am not sure yet how I want to mount it. I might also want to mount some sort of amp meter here, but I may adapt the truck's Tach using ZEVAs sender unit. Anyway, hopefully more to follow...


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## Isaac97 (Jun 3, 2019)

Very cool! I've been silently following your build 
That switch panel would be at home in a nuclear missile silo.


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