# jaaccos conversion daydreaming



## jaacco (Oct 24, 2012)

Hi everyone and thanks for being such a great community! I've been lurking here quite a while trying to learn stuff about EV conversions and the amount of information here is just staggering!

Anyway, I've been compiling a hypothetical parts list here with my limited knowledge and based on components I've noticed people liking here. At the moment this is just idle mind at work as I haven't even narrowed down a possible donor vehicle yet (that's actually really hard considering it should be interesting and practical enough to keep me hooked for many years yet not be too pricey/worn). I have used these assumptions while working on my drivetrain list:

- Must work in winter with temps down to -20C
- Minimum acceptable range 40km on above conditions
- Must have good performance, ~<7-8s on 0-100kmh
- Flexible charging from 10A 230V, 16A 230V and 16A 3-phase 230V sources

As I'm really just learning this stuff I'd really appreciate comments about the things I've selected so far and of course tips about items I'm missing completely!


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## dougingraham (Jul 26, 2011)

Your parts list looks pretty good. I used the Netgain throttle position sensor with the Soliton 1 and I would recommend that. The Evnetics TPS is probably good but the Netgain one works so well with the original throttle cable assembly found in cars. The Soliton Jr is a good choice and I almost wish I had used that instead. The Soliton 1 is huge and it would have been a lot easier to fit a jr in the car. I would have been able to fit at least 3 more batteries under the hood with a Jr. I don't know if you will reach your 7 sec 0-100kph time unless the car is pretty light. It is possible but you may have to mess with gearing to get there.

Good luck!


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## jaacco (Oct 24, 2012)

Hey that Netgain throttle sensor looks really good compared to Evnetics and the price is the same too. With adjustable travel and springs OEM pedal feel should be easy to retain. I've updated my list!

You're definitely right about the performance, with a 132kW effective peak (and I think max torque of 200-250Nm?) I think 8s 0-100 might be realistic for a 1300kg car if you don't need to do 2-3 gearshift.


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## Yabert (Feb 7, 2010)

jaacco said:


> You're definitely right about the performance, with a 132kW effective peak (and I think max torque of 200-250Nm?) I think 8s 0-100 might be realistic for a 1300kg car if you don't need to do 2-3 gearshift.


Based on Kostov graph, the Alpha 11 torque is 230 Nm at 600A.
If you need more performance, buy a Soliton 1 and burn rubber or destroy mecanical gears with an available 380 Nm of torque!..


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## mizlplix (May 1, 2011)

Welcome to the forum, JAA.

When designing an EV there some points to ponder.

1-Pick a vehicle you* really like* as you will have it for a long time.........
(not because it was free or you owned it)

2-Think *light weight*. Every pound lost means better performance. Acceleration and mileage. 

3-*Be realistic* with your goals and budget. Green is costly and challenging. (Buy once, buy correctly)

4-Start a *project planning book* . A loose leaf binder so pages can be changed/added to keep it current. (You will change your mind a LOT)

5-Read, study, plan, read, ask only one question at a time on the forums, and did I mention *read*? (youtube, manufacturers sites and several good web sties: DIY-EV, Endless sphere, Buggys gone wild and AEVA) 

6-Watch the classifieds here on the forums and elsewhere. EV Trading post, ETC. But, beware of scammers. They seem to prey on specific areas where people love what their doing.

The motor is a costly item as is the controller, but the rest of the supporting stuff (adapters, hubs, mounts, boxes, contactors, relays, converters, fuses, ETC) together, will be as costly. BUT, the batteries (cells) will be your biggest hit. Choose the brand and size early to plan the box size and car mounting.

Transmission: Auto or manual? Clutch or not to clutch?

Planning is the key.

Miz


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## jaacco (Oct 24, 2012)

Yabert said:


> Based on Kostov graph, the Alpha 11 torque is 230 Nm at 600A.
> If you need more performance, buy a Soliton 1 and burn rubber or destroy mecanical gears with an available 380 Nm of torque!..


Actually I put Soliton Jr on my list because I was under the impression that K11A can't reliably deal with 250V/1000A bursts. Jr is the single biggest performance limiting item in my list and I'll definitely change it if possible, price bump is ~5% of the shopping list total.

Thanks for the checklist Miz!

I also added a alternative budget sheet to my list and to me it suggests that cheaping out is not an option when speaking about this level of money. For meager ~30% savings you lose ~60-75% of performance and ~40% of range.


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## mizlplix (May 1, 2011)

Reading graphs and ratings are OK, but in the real world, your Jr controller is as good as your specified battery pack. CALB's are good cells, but those will only do 600+ amps only intermittently and for very short bursts. 

I know, my pack of 36-130AH CALBs see a 600+ amp spurt for maybe 1-2 seconds and have a big sag at that point (in 80F-90F ambient).

But I am exceeding the speed limit at that point too...LOL

Miz


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## jaacco (Oct 24, 2012)

This is an excellent point Miz! Is there an easy way to calculate the max reliable current discharge for a given battery pack configuration? I've seen discussion about discharge rates but it's a bit hazy at the moment.

The other battery question I'm hazy too is pack expandability. If my starting pack is 320V nominal and the controller max input is 340V, I can't add much more cells in series to get more capacity. I've seen mentions of doing multiple battery packs which I think means connecting the packs in parallel but that seems like bad idea if your goal is max voltage to motor?


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## jeremyjs (Sep 22, 2010)

Just out of curiosity. Are you going with the calb CA or SE cells?


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## Yabert (Feb 7, 2010)

jaacco said:


> Actually I put Soliton Jr on my list because I was under the impression that K11A can't reliably deal with 250V/1000A bursts.


Like Miz said, the power limitation will be your battery pack. So based on the 600A peak from battery, the Alpha will take 1000A up to 162v.
Why? Let say, 100s sag to 270v at 600A that give 162 Kw / 1000A = 162v

The advantge here is the large torque from 0 to mid range rpm (faster acceleration) and the flat power band from mid range rpm to peak power.


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## jaacco (Oct 24, 2012)

Yabert said:


> Why? Let say, 100s sag to 270v at 600A that give 162 Kw / 1000A = 162v


I don't understand that one . This sag thing is hazy. I picked a 320V nominal pack voltage so that I could get the full 250V to the motor at full acceleration assuming cells provided enough discharge to sustain max A. I specified 70V (~20%) margin purely based on impression I got from numbers I think I've seen people posting. 

I tried looking more into the discharge thing. The 60Ah CALB cells I've chosen for the moment are rated for 3C continuous and 10C short discharge. I'm making a naive assumption here that since C=1A*1s it means that if I need 600A it requires total pack discharge rate of 600C. Since I have specified 100 cells it means needing 6C per cell, which is at under the specified max short discharge rate?


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## Yabert (Feb 7, 2010)

C = capacity. In your case 60A.
3C = 180A and 10C 600A (not 6C).

Sag is a voltage drop caused by internal cell impedance (resistivity).
In my example, if Calb 60Ah cell have an impedance of 0.00083 ohm (my guesstimate) the voltage will drop to 270v with a 600A load. 
0.00083 x 600 = 0.5 and 3.2v - 0.5v = 2.7v x 100 = 270v

That is theorical!


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## MN Driver (Sep 29, 2009)

You can push more than 250v through that motor. 250v is a nominal rating, not a max rating.

For example with the Kostov 9 HV, it's a 220v motor nominal which would push full amps in the mid 4000's RPM but you can push 270v through it to extend that out. That sort of voltage at 600 amps and your motor will be pushing full amps or close to it past about 5500 RPM. Of course if you push both that voltage and power through a 49kg Kostov 9 motor for very long, you'll be letting a bunch of smoke out.

You should be able to push over the 250v with no problem, it is definitely not the limit. Going over the voltage or amperage in the rating specs is overload and going over makes extra heat and you need to limit the time at overload and watch your temperatures but I don't see any reason why you'd need to limit the voltage to that motor with a Sol Jr and a 60Ah pack. Be absolutely sure you have a working tach sensor and limit the RPM though. I'd be sure to get the CALB CA gray cells if you plan to pull 600 amps.


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## jaacco (Oct 24, 2012)

Thanks for the pointers, I think I figured out the C thing now . So the CA series cells are allegedly good for 10C discharge for <10s with a calculated 15% voltage sag which means that a 100x60Ah pack can supply 600A to the controller at 270V (163kW). 

While there I had a noobie d'oh! realization that if the controller can feed the full 163kW it gets from pack to motor at a lower voltage, then of course the current is going to be higher! Which means that if I think high lower rpm(volt) torque can be usable then the 600A peak of Soliton Jr. might not be enough. That got me reading this. 

And now I have lots of things to think about the relationship of max current and max rpm in a DC motor, about max usable torque @ specific rpm and gearbox durability and gearing in general .


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## mizlplix (May 1, 2011)

As for "gear box" durability...

It is dependent on the vehicle weight and tire traction patch.

Even a Chevy three speed will last under 1,000HP if the car weighs 2,000Lbs and it has 175-70-15 tires. (No way to hook it all up)

A clutch dump from a Small Block Chevy with a 50# flywheel at 6,000RPM is far more powerful than most EV motors, even with 1000 amps on tap.

Any transmission built for a V8 engine in a 4,300Lb car will be durable enough for an EV. 

Miz


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## jaacco (Oct 24, 2012)

You're quite right Miz! I think that any sub-600A level torque generated by K11A will not be problem on any of the car candidates I've been considering so far.

I added another speculative sheet on my list to better understand how the battery voltage affects things. Since I now realize that if the available max torque is always the same as available max current from the pack (within certain limits), then pack voltage only sets the shift points (and max speed) via the maximum motor rpm it dictates.

This is probably obvious to you guys but to me this was an eye opener about how useless the peak kW power is in this context! So with the assumption that the K11A max rpm of 4460 at 211V/500A will scale linearly so that max rpm at 105.5V/500A will be 2230, I started playing around with the amount of cells (=voltage) in my sheet to see how they change max speeds at different gears on one candidate car. And I found that a nominal pack voltage of 144V is good for a max 2587rpm and a max speed of ~110km/h under 500A acceleration. With 193Nm torque from 500A available I think 3 shifts are needed on 0-100km/h and I guesstimate that it's maybe 9-10s, a lot better than I previously assumed from the nominal ~50kW peak rating!

And with this realization that I don't necessarily need a mad high-voltage pack I also realized that I don't need a top of the line controller either. Hence I updated the list to use 45x70ah Calb CA cells and a OpenRevolt 144V/500A controller which makes the initial shopping list total cost look a lot more palatable. To improve performance and range I can swap the controller and add battery cells at my leisure later on, hmmmmm.


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## dtbaker (Jan 5, 2008)

jaacco said:


> ... I updated the list to use 45x60ah Calb CA cells and a OpenRevolt 144V/500A controller which makes the initial shopping list total cost look a lot more palatable. To improve performance and range I can swap the controller and add battery cells at my leisure later on, hmmmmm.



... I just noticed an 'open box' sale in classifieds for a Zilla..... looked like a great deal.


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## jaacco (Oct 24, 2012)

forever the optimist said:


> <..> a nominal pack voltage of 144V is good for <..> maybe 9-10s, a lot better than I previously assumed from the nominal ~50kW peak rating!


Added some crude acceleration calculations to my sheet and found out how wrong I was on above. An acceleration of 0-100 on a 1400 kg candidate car would take over 17 seconds with 144V/500A .

So I played around with the sheet and settled to a initial pack of 192V with 600A max current to bump acceleration to more acceptable ~11 seconds. This meant updating the parts list to use 60x70Ah Calbs and reverting to Soliton Jr. On the upside, when I want to upgrade I need to only add 40 cells on the system to boost acceleration to ~7 seconds without other component changes.

Also cleaned up the sheet of the other speculative builds so there's just the primary one with K11A on a 1400kg car and another one with K9220V on a 1300kg car.

Next: Need to find out more about clutch vs clutchless. At the moment I have a theory that clutchless operation could be assisted by electronically matching motor rpm to the actual gearbox gear shaft rpm about the to be engaged, hmm.


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## jaacco (Oct 24, 2012)

About clutchless shifting. I'm thinking that on cars having a speed pulse sender in the diff or transaxle it wouldn't be terribly complicated to create a following sort of Arduino-controlled auto-throttle system:










Simple system with only two gears to shift between. 

Shifting from neutral position: 

Press clutch pedal -> switches motor controllers throttle source from gas pedal to Arduino (also drops rpm to 0)
Start moving shifter to 1st gear -> SW1 closes
Arduino calculates the 1st gear rpm by multiplying the diff speed signal by 1st gear ratio 
Arduino sends throttle signal based on above rpm to motor controller
Controller raises/lowers motor (=tranny input shaft) rpm
Complete shifter movement to engage gear

Shifting from in-gear to neutral position should be easy enough with just lifting of gas pedal. The difficult bit might be designing sensitive enough but not too sensitive switch system on the gear linkage.


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## Yabert (Feb 7, 2010)

Your problem is here...


jaacco said:


> Controller raises/*lowers* motor (=tranny input shaft) rpm


No regenerative braking with DC series motor controller.
If you need sport performance, keep the clutch!


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## jaacco (Oct 24, 2012)

Yabert said:


> Your problem is here...
> 
> No regenerative braking with DC series motor controller.
> If you need sport performance, keep the clutch!


I'm not sure how regen braking is related? Note that operation is done when gearbox is still in neutral, input shaft is not connected to gear.


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## Yabert (Feb 7, 2010)

The DC motor controller can't slow down the motor!


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## jaacco (Oct 24, 2012)

Ah I see! So when upshifting you must wait for the motor rpm to drop (which is not fast assuming low rotating mass), hmmmmmm.


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## tylerwatts (Feb 9, 2012)

Jaacco

What Yabert means is the DC controller can't electronically slow down the motor, and any free-wheeling electric motor will NOT slow down very quickly as there is so little drag in the rotor, only the bearing friction of the motor and if clutchless the input of the transmission.

This is where a clutch makes a BIG difference for performance with a DC motor, the clutch is used to slow down the motor and seperate the over-revving motor from the transmission to select the gear in the first place.

An AC motor can be slowed, so a clutch could be avoided as you say/ CTS_Casemod is including this control in his conversion with an AC motor, but with your DC setup it will not be possible. The only potential alternative if not using the clutch is to mechanically brake the motor (say a small brake disc on the secondary shaft) but this is unnecessarily complicated and a clutch would be a far simpler solution.

Any concerns of the strength of the clutch or it slipping are eliminated by the fact a Soliton controller, and most others can adjust it's ramp up rate, which is how quickly it goes from no current to the motor to full current, and if this is more gradual then the clutch will not be jolted to break traction, and likewise the tyres will not be jolted and will grip better at launch.


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## jaacco (Oct 24, 2012)

Yes I understand it now, no easy way around it with DC. Pity as I had ideas about motor placement in rear-transaxle cars which are all rendered moot by the clutch requirement if not addressed by a motor brake on the tailshaft .


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## tylerwatts (Feb 9, 2012)

One other idea that seems no more complicated to impliment using your method would be an electronically operated clutch! Been done so often in performance/race cars, a simple DIY approace would be a servo/solenoid (admittedly a big one) operated hydraulic clutch, as there's no clutch slip taking off as the electric motor is not spinning, and you can use a small dampener on the solenoid to smoothly release the clutch for transmission changes, then you wouldn't need a clutch pedal either.

Maybe complicated a bit by needing to tell the circuit you intend to change gears but I thought something like the 'snapping' action of a torque wrench activating a switch when attempting to move the lever forwards/backwards would trigger the circuit to hold the motor at the required rpm of the gear selected (which is perfect for deselecting without clutch) and trigger the release of the clutch also, then the reverse when releasing the gear lever when in the next gear would trigger the engagement of the clutch which would slow the motor to the gear speed mechanically. and the relative torque on the clutch would be nothing and wouldn't adversely wear the clutch or heat it or anything!

Heck, I'm thinking I need to look at a setup like this! It would be very similar to the Toyota MMT transmission which operated a bit like a centrifugal clutch disengaging when the throttle is released to select the next gear (was a crude as it sounds for a car!) but it worked well enough!


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## jaacco (Oct 24, 2012)

The need to lower DC motor rpm's externally probably makes 'my' idea too complicated to implement but out of curiosity I looked into slowing a DC motor and there seems to be two ways.

Dynamic braking which basically uses a resistor pack for soaking the remaining kinetic energy from the motor. I'm not sure whether warp/kostov DC motors allow such a circuit and I couldn't finish the calculation for the kinetic energy of motor/load at at specific rpm's in order to determine the needed resistor pack size. Since no-one seems to be using this approach in EV's I think the resistor requirements are not feasible.

Mechanical axle braking. I looked into it and solenoid-actuated brakes are readily available and are quite affordable. In fact I have one rated at 55Nm to play around with, not too expensive either at ~120€. Again I'm having problems on calculating motor/load kinetic energy to determine suitable brake Nm rating and the durability of brake pads in continuous automotive use is also an uncertainty.


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## dougingraham (Jul 26, 2011)

jaacco said:


> URL="http://www.engineersedge.com/instrumentation/components/dynamic_braking_resistors.htm"]Dynamic braking[/URL] which basically uses a resistor pack for soaking the remaining kinetic energy from the motor. I'm not sure whether warp/kostov DC motors allow such a circuit and I couldn't finish the calculation for the kinetic energy of motor/load at at specific rpm's in order to determine the needed resistor pack size. Since no-one seems to be using this approach in EV's I think the resistor requirements are not feasible.


Electrodynamic braking won't work on a series wound DC motor unless you do sepex. It would work on pretty much any permanent magnet motor.

Clutchless shifting up is no big deal unless you need to do it quickly. Waiting for the RPMs to match seems to take forever. It probably isn't as bad if you have removed the flywheel but still you wait and if you miss it you will have to tap the throttle. And downshifting you just tap the accelerator.

Lighten the flywheel and keep the clutch. If you like to drive the car like a car this is essential.


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## jaacco (Oct 24, 2012)

Thanks for the clarification about the sepex requirement, I suspected there was a limitation like that. You're absolutely right about the clutch thing, however I have some cars with drivetrain like this on my candidate list:










If you could disregard the clutch without sacrificing driveability, the EV component packaging could be a lot more interesting - you could dismiss the torque tube completely and connect the motor directly to transaxle with controller nearby under the trunk and put the full battery pack and charger under the hood. That would mean easier weight distribution management and also keeping the cars center of gravity nice and low.


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