# Porsche 944 conversion DC/LiFePO4



## rillip3 (Jun 19, 2009)

Quick note on the heater, IIRC Gav was able to just cut a block out of the old fluid heater and use a high temperature epoxy to bond the ceramic heater to it. Now the heat is all in the same place as it was before, with no kludging of the dash needed.


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## DavidDymaxion (Dec 1, 2008)

A 944 should be a great car to convert. If it's affordable you might want to go with the higher voltage motor and controller. You can still run a lesser voltage battery pack, and then easily upgrade to high voltage in the future.

If there's room, you might be able to add a rotary table to your mill and do what a lathe would have done. Here are some pics where I did that for my adapter: http://explodingdinosaurs.com/9electric/adapter2


rwaudio said:


> ... Warp9 motor. nothing different, nothing new, but it should do what I want, I was very close to choosing the 192V Kostov 11 over this, however a ~15xV pack is more practical and cost effective.
> Warp Drive 160V 1000A or 1200A controller. this controller is fairly new, it was a tight race between this and the Soliton1, however with the real world power that I will be able to get out of the batteries the Soliton1 is a very sexy but over budget/overkill solution.
> Thundersky LiFePO4 160AH or 200AH 48 cell pack I was really hoping for CALB 180AH cells, to have a little more continuous current 720A vs 480/600 for either of the TS solutions but Randy at CANEV has a pretty damn good price on the TS cells and that will most likely make the decision for me. ...
> 
> Adapter/Coupler I have a small CNC machine so the adapter plate(s) shouldn't be to hard, the coupler on the other hand might be a little trickier since I don't have a lathe. It will retain the clutch though, and probably be similar to a VW conversion on here that used a taperlock pulley setup from Grainger. (I apologize I forgot this members screen name)


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## rwaudio (May 22, 2008)

rillip3 said:


> Quick note on the heater, IIRC Gav was able to just cut a block out of the old fluid heater and use a high temperature epoxy to bond the ceramic heater to it. Now the heat is all in the same place as it was before, with no kludging of the dash needed.


Thanks for the tip, if the fluid heater heats up too slow then I may have to go with 1 or 2 ceramic heaters in the core. Overnight the car will be in the garage, however with the potential of 9 hours parked at work in freezing conditions I may have to either suppliment the heating or add something small that runs off the 115/230v line when charging for both me and the batteries.


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## rwaudio (May 22, 2008)

DavidDymaxion said:


> A 944 should be a great car to convert. If it's affordable you might want to go with the higher voltage motor and controller. You can still run a lesser voltage battery pack, and then easily upgrade to high voltage in the future.
> 
> If there's room, you might be able to add a rotary table to your mill and do what a lathe would have done. Here are some pics where I did that for my adapter: http://explodingdinosaurs.com/9electric/adapter2


That's exactly what the initial plan was, doing the soliton1 and the kostov11 off a 144v pack, with the intention of doubling it to a 288v pack. However the 2nd half of the pack is way beyond my budget (a LiFePO4 of any kind is a stretch of the budget anyways), and I don't think I would be happy with the performance and range using the initial smaller pack. So after a reality check I've settled on what will probably be a good compromise of performance and price. I don't really need that much top speed, I spend at most 2 or 3 minutes of my commute at 100km/h and most days traffic is too heavy to even reach that speed, so the majority of it is ~60-80km/h. So something with good acceleration to 60km would make me very happy.

I think I still have the initial plan up on my blog robinwainwright.wordpress.com under Electric Porsche which outlined the "big plan" however this is a "real plan"
Thanks again for the input, this is exactly what I need to work through some of the issues/questions as I learn.


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## Duncan (Dec 8, 2008)

Hi Rwaudio

Just a thought on your battery choices - 48 off 200Ah

I was originally going for a similar pack to allow for 600 amps as 3C

The controller guys told me (I hope I understand) that the controller is a power in - power out device

I had assumed that I would take 600Amps from the battery to feed 600 amps to the motor

But no

When the motor only needs 50v I would be using 200 amps at 150v battery to get 600 amps motor (50v)

This means I could go from a 150v 200Ah pack to a 200v 100Ah pack - saving 100kg and $3,500 and still not cook the batteries 

I lose in range and I have slightly less power available so my acceleration will slacken off

150v x 200a x 3C = 90Kw
200v x 100a x 3C = 60Kw

But I save in batteries and weight - my 650Kg target may be possible!


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## Woodsmith (Jun 5, 2008)

rwaudio said:


> Thanks for the tip, if the fluid heater heats up too slow then I may have to go with 1 or 2 ceramic heaters in the core. Overnight the car will be in the garage, however with the potential of 9 hours parked at work in freezing conditions I may have to either suppliment the heating or add something small that runs off the 115/230v line when charging for both me and the batteries.


Could you include a mains powered heater in the heating fluid so that it heats the car when it is plugged in to charge? That and an air heater in the cabin would make life easier in the mornings and where ever you can plug in during the day.


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## rwaudio (May 22, 2008)

Duncan said:


> Hi Rwaudio
> 
> Just a thought on your battery choices - 48 off 200Ah
> 
> ...


 
Hi Duncan, this is one of the things I'm counting on, I would never see the 1000A or 1200A maximum current if the hard limit was 600A from the battery. The only reason I would go up to 200ah from 160ah is for the extra 3C current not for the range. Which would allow me to put 1200A to the motor up to roughly 72V motor voltage minus losses. The extra AH's would also allow me to drive the car like a Porsche without having to worry as much about range during normal drives, but it would give me some good range if I baby it a little.

I'm not sure if I mentioned it in my intro, but this car is not just about converting a car to electric to be an efficient commuter. It's about a project car, that performs well without the impact on the enviroment or my wallet (after the conversion cost) if I drive it hard on sunday afternoon. Most of my friends are building muscle cars or 50's pickups with huge V8's, some of them can waste 40 bucks on gas for a short but spirited cruise, I want something different, I want something that I can drive to work every day if I feel like it. It should perform well for a street car, but it's not a race car. I would basically like to put a little shame to those big V8's in heavy cars at legal speeds, where I live the common speed limits are 60/80/100km/h (roughly 37.5/50/62.5mph) so I would like to be quicker to 60, close at 80 and watching them go at 100. I think that's resonable performance for an EV with somewhat realistic expectations.

I enjoy driving, and although I don't drive fast I stay very close to the speed limits, I don't mind reaching those limits resonably quickly. My daily driver is an '07 Infiniti G35 sedan with 306hp, 268ftlbs of torque. Based on motor charts that I've seen for the warp9, at 1200A I should be right around that 270ftlbs of torque at low RPM. But this torque comes on at drastically lower RPM and the Porsche will weight 500 or 600 lbs less.

There will be days when I do everything I can to keep the battery amps below 150 or 200, and try and cruise at less than 100, however there will also be the days that I will draw max (3c) battery amps for short bursts at every light or stop sign. This will definatially cut down the range, but I'm trying to design this car for my wants and not just my needs. And I think that catering to both my wants and needs will keep this conversion enjoyable to drive for many years to come.


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## rwaudio (May 22, 2008)

Woodsmith said:


> Could you include a mains powered heater in the heating fluid so that it heats the car when it is plugged in to charge? That and an air heater in the cabin would make life easier in the mornings and where ever you can plug in during the day.


I think this is a feature that will make it's way in eventually, although my garage isn't heated, it is very well insulated. When it's -35C outside the garage is usually around -3 to -5C inside, so mornings are never that bad when the car is in the garage, however at work it could be chilly. I'm not sure if I will be able to get them to install anything larger than a 15A 115V ciruit at work for me to charge from but there is potential since we still have some capability because we use to use 208V/230V and 480V 3 phase for some shop testing that we no longer do. So a 230V 30-50A circuit might be possible if I ask nicely. This would provide plenty of head room to do some heating along with the charging. With a 115V 15A circuit I would have at most 100-200watts of extra power without blowing breakers. Unless there was some sort of trigger once the battery charger turned off that turned on a 1500W heater or something like that. (gives me some ideas  thank you!)


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## MNEVRL (Aug 9, 2010)

rwaudio said:


> I've decided on a 1986 Porsche 944.
> 
> Power Steering this is the one weak link in the Porsche, it leaks, and when it leaks it destroys the ball joints. I have a feeling that mine leaks already, so it's either going to need new seals at the very least along with an MR2 pump or similar to power it. OR I will try to compare this with the cost of swapping out for a manual rack out of an older 944. I may have to test drive a car with the manual rack and see if I like it, the 944 with power steering is still a lot "heavier" than my Infiniti G35.


I can't advise on anything EV related, but as a 944 owner that has swapped from power to manual steering I'll say go for it. Best thing I've done to mine so far. 

If your PS system isn't leaking yet, it will be soon. These things are absolutely notorious for it. The rack itself, the pump, the reservoir, pretty much the entire system will eventually start bleeding all over the underside of the car and your garage floor. The passenger side swaybar bushings swell and turn to mush after getting a PS fluid bath.
Reseal everything? Sure. Give it 3 years and it'll be leaking somewhere again.

The only possible "gotchas" here are weight and tire size. 
If your EV conversion will approximate the weight over the front axle from the ICE and it's related junk you're fine. Add too much weight or go much beyond a 225 section tire up front and you'll definitely feel it and a need to develop Popeye arms for the low speed stuff.

Your '86 is an early offset and is quite easy and inexpensive to convert.


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## rwaudio (May 22, 2008)

MNEVRL said:


> I can't advise on anything EV related, but as a 944 owner that has swapped from power to manual steering I'll say go for it. Best thing I've done to mine so far.
> 
> If your PS system isn't leaking yet, it will be soon. These things are absolutely notorious for it. The rack itself, the pump, the reservoir, pretty much the entire system will eventually start bleeding all over the underside of the car and your garage floor. The passenger side swaybar bushings swell and turn to mush after getting a PS fluid bath.
> Reseal everything? Sure. Give it 3 years and it'll be leaking somewhere again.
> ...


This is something I'm glad to hear, I'm new to 944's but that comes up endlessly along with the timing belt when people talk about owning a 944. Do you have any other details about the parts required? I don't think weight will go up too much, and the car has 195's or 205's on the front right now and that's how it will stay. It would also be nice not to have to power that MR2 pump, and my 944DC doesn't need a dirty leaky power steering system and leave it's mark everywhere I park.


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## Woodsmith (Jun 5, 2008)

rwaudio said:


> Unless there was some sort of trigger once the battery charger turned off that turned on a 1500W heater or something like that. (gives me some ideas  thank you!)


Last winter it was bitter cold here with a foot of snow. I put a fan heater in my Diesel car and set it on a timer to come on an hour before I got up in the morning. It was so good getting in a car that I didn't have to warm up, de-ice and de-mist before I could drive it.


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## MNEVRL (Aug 9, 2010)

rwaudio said:


> Do you have any other details about the parts required?


Everything right here, parts and a how-to:
http://forums.rennlist.com/rennforu...7-944-power-to-manual-steering-rack-swap.html


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## rwaudio (May 22, 2008)

MNEVRL said:


> Everything right here, parts and a how-to:
> http://forums.rennlist.com/rennforu...7-944-power-to-manual-steering-rack-swap.html


Thanks for the link, that looks like a simple process especially when the engine comes out. I've found a local '83 944 with a blown engine but apparently good condition manual steering rack, I'll probably buy it this weekend. The whole car is only a couple hundred more than sourcing a rebuilt rack from the US. Since I'm taking a perfectly good motor out of my 944, and I will have a 944 with a blown motor I might swap in the good one, fix it up and sell the '83 in running condition to help fund the cost of the electric. I wonder how easy it will be to put a power steering rack INTO an '83.


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## rwaudio (May 22, 2008)

Since most 944′s have power steering leaks, mine included. The easiest and cleanest way to get rid of them is to swap in a manual steering rack. The biggest benefit is no longer wasting energy on the power steering pump, plus it would be somewhat embarrassing if my electric car had an “oil” leak!?! Fortunatially the first year of the 944 (1983) came with a manual rack, along with some of the racing versions however those are tough to find. Trying to get a used or remanufactured rack up here in Canada was proving to be an expensive task. On my birthday an ad showed up on kijiji, an ’83 944 with a blown engine for a good price. This is what I had hoped for when starting the project, a cheap 944 with a blown engine! To bad this one is the “old” style and I’m not a big fan of the interior styling. However after much contemplating I decided to buy the car with the end goal being swapping the steering rack, and also swapping the good engine out of my 944 into this ’83. Then I have a running car that I can sell to help fund the electric conversion.
In short this makes a lot more work before I even start my electric conversion, however by selling this ’83 along with the other parts of the ’86 my donor car will cost nothing or maybe even make me some money in the end.



Engine..



No Engine..

I also bought a small MIG welder that I will use to build brackets/mounts as well as the aluminum battery boxes. I welded up a quick and dirty cart to allow me to move the engine around. Along with removing an engine, welding is something I haven’t done since high school but it’s all coming back slowly, thanks Mr. Nickel!



Engine and cart, you can just see the hole in the side of the engine!



And a nice view of the hole, easy to see why this car was cheap. I’ve pulled out a few pounds of aluminum and steel, including the connecting rod, parts of the piston, oil pan and block.
I’m just about ready to start the engine removal process all over again on the actual donor car. Then I will be installing that engine in the ’83 and fix it up a little. I’m actually quite surprised how easy things came apart on a car that is over 27 years old, nothing was rusted or seized even the exhaust system came off without a problem.


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## Woodsmith (Jun 5, 2008)

rwaudio said:


>


Duct tape and bondo will soon sort that out.

That is a good find. I'm sure that the sale of it will certainly bring in good funds so worth the effort.
Also a chance to see if thare is anything else worth swaping over.


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## rwaudio (May 22, 2008)

Woodsmith said:


> Duct tape and bondo will soon sort that out.
> 
> That is a good find. I'm sure that the sale of it will certainly bring in good funds so worth the effort.
> Also a chance to see if thare is anything else worth swaping over.


As long as I shove all these parts back in I should be good to go. (This is what came out and I haven't taken the engine apart yet)


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## rwaudio (May 22, 2008)

I have decided to use the same Headway 10ah LiFePO4 cells that will power the car to create my 12v battery.



While creating some brackets for a customer I decided to create a few of my own brackets on the CNC machine since I was all setup. The brackets are made from 0.125″ aluminum flat bar with a milled recess to let the screws sit a little deeper so there is still plenty of thread going into each cell.



The cells are configured in a 4s3p configuration with the included orange holders. All connections receive a coating of deoxit during assembly and the custom bus bars join the cells in the required electrical configuration.



The bottom of the battery uses simple 6 hole rectangular bus bars which were very simple to manufacture.



The top of the battery uses some angled bus bars that were a little more difficult to make but well worth it for the easy of assembling the finished pack.



I still need to install the bolts in the outer two plates that will become the battery terminals as well as smaller wires that will connect to the BMS from each group of parallel cells. After I remove the stock battery from the car I will give a size and weight comparison of the new vs old battery.


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## rwaudio (May 22, 2008)

Work has moved towards getting the engine out of the '86 ready for it's transplant into the '83. This involves moving over the entire wiring harness, any sensors or brackets that are different between the two years as well as the entire intake and vacuum system. After stripping down the "blown" engine out of the '83 it turns out the balance shaft belt was broken, however the timing belt was intact. Even with the extensive damage the engine isn't actually seized, the camshaft is seized and the timing belt was strong enough to keep the engine from turning. After sliding the timing belt off (something I'm sure isn't supposed to be possible without loosening the tensioner) the crankshaft still turns nicely. Both balance shafts still turn but one has slightly more "drag" than the other which could have been part of the cause. After removing one of the motor mounts I found the hole is much larger than previous thought.

It looks like all of the parts that I need are in good shape though, and the transfer of parts has gone very smoothly, the engine will be ready to go in the '83 fairly soon.
On the EV side though, the Warp 11 HV has arrived, and I will start the design for the coupler and adapter. The motor is a thing of beauty and I can't wait to start working on getting it into the '86.

Even though the Warp 11 HV is a monster in the EV world, it's still very compact compared to the stock 2.5L Porsche Engine. As shown above with the Porsche engine and starter motor for scale.

I've also been working on the battery charger design, instead of using an off the shelf solution I've decided to create individual cell chargers in the form of industrial quarter brick dc/dc converters. Each of the 90 series groups of cells will be charged by it's own 48v to 3.3v dc/dc converter adjusted up 10% to 3.65v to charge each cell to the perfect voltage every single time. This eliminates the need for a shunting BMS or other intrusive charging monitor. The dc/dc converters will be in groups of 15, with these groups fed by an industrial grade 85-264v AC power supply. By adding more of these power supplies the total charging power is scalable from 1.5kw up to 7.5kw with the existing dc/dc converters. The charger/bms/gauges are all part of the same system and the total cost will be around $1000 instead of $1000-2000 for a charger, a few grand for a BMS and a few hundred for gauges.

All of the systems will be tied together with an Arduino Mega based microcontroller that will monitor each cells voltage, battery current, charging current, battery temperature, cabin temperature, SOC, total pack voltage, and any other systems that need control or monitoring.


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## Yabert (Feb 7, 2010)

Realy interesting project.

Your weakest link seem to be the batteries and they give you over 200 kw.... this not bad!!
This set-up will give you great acceleration.
I like it!


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## jwrape (Jan 5, 2011)

subscribing, i like the porsche 944 as a EV


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## Bowser330 (Jun 15, 2008)

read through your blog and am really looking forward to your results.

dont forget to count the weight savings from using lighter rims than the stock 944.


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## rwaudio (May 22, 2008)

Bowser330 said:


> read through your blog and am really looking forward to your results.
> 
> dont forget to count the weight savings from using lighter rims than the stock 944.


That's true, I hadn't thought of that! I bought the car with the light wheels and was consdering that "stock" even though it isn't. The Fuch wheels are amazingly light. 

I will have an update soon, when I dig deeper into the design of the adapter plate/coupler. I'm still worried about the clutch slipping, but I'd like to keep the clutch, and didn't include a Porsche racing clutch $$$ in the budget. May have to be an upgrade shortly down the road.


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## dtbaker (Jan 5, 2008)

I wouldn't worry too much about the clutch as you don't need it at all from a stop.


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## rwaudio (May 22, 2008)

dtbaker said:


> I wouldn't worry too much about the clutch as you don't need it at all from a stop.


Define "don't worry"?

Don't use it(install it)? or It probably won't get damaged?
I have a warp11hv, I'll be using a soliton1 and enough headways to give me about 270kw/300ft-lbs of torque.

Stock engine was around 150hp/150ft-lbs, I've been told the tranny can handle tons of torque as long as it comes on smoothly (reasonable soliton1 slew rate). Does anyone know the holding torque of your average stock clutch for a 150hp engine?


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## dtbaker (Jan 5, 2008)

rwaudio said:


> Define "don't worry"?
> 
> Don't use it(install it)? or It probably won't get damaged?
> I have a warp11hv, I'll be using a soliton1 and enough headways to give me about 270kw/300ft-lbs of torque.
> ...


I would suspect the tranny can handle the 300 ft# without slipping, I didn't realize the stock 944 was only 150hp?! but perhaps heavy springs are available? I would retain the clutch as it helps with downshifting, and faster up-shifting.


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## rwaudio (May 22, 2008)

dtbaker said:


> I would suspect the tranny can handle the 300 ft# without slipping, I didn't realize the stock 944 was only 150hp?! but perhaps heavy springs are available? I would retain the clutch as it helps with downshifting, and faster up-shifting.


The engine I pulled out was 150 or 155hp, some of the later models and Turbo were in the 250hp range, mine has the tranny out of a turbo so I should be good there, but a stock (non turbo) clutch with about 60% left. I should be able to do 0-60mph in 2nd gear with no shifting, but I'd still like to keep the clutch, just like you said for down shifting and a faster shift to 3rd and 4th if I ever use it.

I guess only time will tell, at least there are racing products available since the 944 is a pretty good track car.


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## patrickza (Dec 28, 2009)

Subscribed. I really like your choices in terms of the design. Very similar to what I have planned, when I get the money together. 

The charging system has me the most interested as I don't like the current shunt based systems either. Have you got experience programming arduino's and could you perhaps give us more detail as to how you'll be monitoring all the cells during driving?


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## ragnar (Nov 14, 2010)

rwaudio said:


> Define "don't worry"?
> 
> Don't use it(install it)? or It probably won't get damaged?
> I have a warp11hv, I'll be using a soliton1 and enough headways to give me about 270kw/300ft-lbs of torque.


can you really get 270Kw out of this motor? 270kw = 367.1hp

were talking about this motor right?
http://www.ev-propulsion.com/warp11details.html
*43.7 HP (72 Volts, 453 Amps)*
135 Ft. pounds torque*

so just by putting more volts and amps you get more hp? how do you know how much this motor can handle? and b.t.w. crodriver i saw on your blog.. is this the same motor he is using?
*


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## jeremyjs (Sep 22, 2010)

ragnar said:


> can you really get 270Kw out of this motor? 270kw = 367.1hp


I'm sure you can the only question is for how long. just look at the white zombie. I bet his 2 modded 9" motors put out a good bit more than that, but only for 10ish second bursts.


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## ragnar (Nov 14, 2010)

jeremyjs said:


> I'm sure you can the only question is for how long. just look at the white zombie. I bet his 2 modded 9" motors put out a good bit more than that, but only for 10ish second bursts.


that just depents on the battery pack you have right? for how long you can hold 300+hp??


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## rwaudio (May 22, 2008)

ragnar said:


> can you really get 270Kw out of this motor? 270kw = 367.1hp
> 
> were talking about this motor right?
> http://www.ev-propulsion.com/warp11details.html
> ...


That is correct, 270kw peak electrical power. It is the same motor crodriver is using, however I believe his has been been modified a little by Jim H. mine is stock. 

I'll update more later, but I've decided to go clutchless. 90% of my driving will be in 2nd gear, so getting rid of over 30lbs of rotating steel seems worth it. (38lbs for flywheel/clutch/pressure plate, replaced by an aluminum coupler being made by Charlie of evcouplerconnection.com)

A big thanks to Charlie, since he was the only one willing to work with me on the coupler without charging me an arm and a leg for R&D since nobody but him seems to make a 944 coupler. He's great to talk to, he explained exactly how the coupler was made, how it attaches and why he builds it the way he does. The price is good too! 
I was getting annoyed by all of the people saying I would have to send in my transmission in order for them to build a coupler/adapter. Well in a Porsche 944 the tranny doesn't actually connect to the engine, the tranny is in the rear, and the engine in the front and there is a "torque tube" that connects them. Most people didn't seem to understand this concept and simply replied, you'll have to send in the transmission anyways.


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## rwaudio (May 22, 2008)

ragnar said:


> that just depents on the battery pack you have right? for how long you can hold 300+hp??


The motor is capable of 300+hp but only for short periods of time or it will overheat. The battery pack could put out that power until it was dead, however that would be pretty quickly (about 5 mins) however there is also no way you could maintain that kind of load for 5 mins unless you were driving up a mountain at full throttle. 

So in short, the motor and battery can put out 300hp peak, for the brief periods that I push it that hard. It's not a continuous rating, I'm sure the motor would overheat LONG before the 5 minute mark when the battery is dead.


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## Bowser330 (Jun 15, 2008)

well said, any updates on the build?


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## rwaudio (May 22, 2008)

I was contracted to design a PCB recently and after getting the finished boards in my hands it gave me the motivation to dig back into my own PCB design and fix up the things that I didn't like and finalize what I wanted the board to do. When you have a blank slate and you can incorperate any features you want sometimes it can start to get out of hand. I took a step back and looked at what I NEED the board to do then added some headers for future changes. This PCB can stand alone as a carrier for 16 quarter brick dc/dc converters with simplified input and output connections, or it can be part of a voltage/temperature monitoring system. I haven't designed the rest of the system yet so it was important that this board be able to function independantly. 
Below are some of the design choices and reasons I did what I did.

I started the design for the dc/dc converter charger PCB long ago, but never quite finished because I wasn’t happy with the overall layout, feature set or component selection. Well after a lot of work over the past week I have a design that I am happy with. It includes a new two stage charging setup that will allow a lower initial charge voltage (around 3.0-3.3V but fully adjustable) to keep the current in check when the battery is at a fairly low SOC, once the current drops off to a reasonable level the 2nd stage of can be activated which increases the voltage to the final CV voltage of 3.5-3.6V, also fully adjustable. There is an opto-isolator very close to each set of cell terminals that will be used to collect signals that go to the analog multiplexer and will end up at the Arduino for full system voltage monitoring. There is an on board temperature sensor that will send temperature data to the Arduino, mainly for battery box temperature during the discharge cycle to see if I need to heat some or all of the boxes, but also to monitor the temperature during the charge cycle that will eventually be able to cut off the charger if things get hotter than they should, and sound an alarm. The output of the dc/dc converter is kept as simple as possible to reduce the possible failure points. Some people are using a “resistor” or length of wire to act like a resistor to limit the current output of the dc/dc converter. Although this does work in practice it’s not the most elegant solution as it reduces the efficiency of the charging process and produces a lot of heat. I’ve tried very hard to reduce the connection resistance in the whole system so I’m not about to add resistors on purpose. If we take a step back and figure out why there is such a large current during the first stage of the charging process we learn that it’s basically ohms law (V-IR or in this case I=V/R) that determines how much current the cells draw from the charger. So by lowering the output voltage of the dc/dc converter we also lower the current. This trim function is controlled by a low power resistor that doesn’t affect the output connections to the cells. By lowering the voltage to between 3.0 and 3.3V I can control the charging current or the first stage of the charge cycle. After a short period the cell voltage starts to rise and the current draw goes down, at this point I can switch the charging voltage (via a relay and resistor setup) to the final CV voltage of 3.5-3.6V. By adjusting these two voltages I can control the output current throughout the charging cycle. With the resistor or wire acting like a resistor method mentioned above the initial current is controlled however the overall charge cycle will take longer because the output current follows a lower curve which affects the entire charging cycle. An even more elegant but much more complex method would be to use a digital potentiometer, micro controller and shunt to monitor the charging current and adjust the trim voltage in real time on a cell by cell basis to keep a constant current to every cell, this would be the fastest and most efficient charging method, but more costly in parts, design effort and software. This would also allow the implementation of an entire pack charge current and final charge voltage selection by the end user at any time, or automatic charge current selection based on the AC input voltage to get the most out a wall outlet. This would also let you throttle back the charging current if the outlet is shared to avoid tripping breakers without the random CV voltage problem when doing this with the Manzanita Micro chargers (no offence to the Manzanita chargers, I think they are great, and it was on top of my list until I decided to go with the dc/dc charging method).
Below is the current state of the design, I still need to move around some component labels and add labeling for the various terminals, however the electrical design is very simple.

Below is the same design with only the bottom layer shown, this is where all of the high power traces are routed along with some of the signal or trim traces.

Below is the top layer which mainly consists of the voltage monitoring traces that feed back to the multiplexer, with the exception of one high power trace that allowed the use of wider traces at the input to the main storage capacitor due to the fairly close pin spacing. I will probably add some vias or a bottom layer trace near the input pin of the first dc/dc converter so that current flow from the top layer to bottom layer isn’t limited by the single power pin.

Those of you experience in PCB layouts will notice that all of the surface mount parts mount to the bottom as well as the opto-isolator, relay and temperature sensor. All of the terminals, trim pots, jumpers and the dc/dc converter itself mount to the top.

In the early stages of the design I thought that a 4 layer PCB may be required, however with careful component layout and trace routing everything works very well on a 2 layer PCB. The board itself will be thicker than average at 2.4mm (vs 1.6mm which is standard) this will give a bit more rigidity and strength to the board since the dc/dc converters are somewhat heavy. The traces will all be 4oz copper for extra current handling. I still have to decide on the mounting hole arrangement, there are some holes marked on the layout right now but they are a reminder more than anything and will be revised. The parts count is reasonable and it won’t take very long to solder up the 6 PCB’s that will be used in my setup. There are 11 terminal blocks to handle the input and output connections, 10 of those are high current and one is signal level however it makes things easier to simply use the same terminal block in all locations. There is an RJ45 connector with a non standard pin out that CAN NOT be connected to any other Ethernet type device, this connector was chosen because of the simple and cost effective shielded Ethernet cables available in virtually any color and length. This will feed back the temperature and voltage signals to the arduino and carry the data signals and 5v power for the multiplexer. There is a block of terminals that would accept jumpers or other headers/connections/resistors to allow changes to be implemented in the voltage trim process. This basically makes the board somewhat future proof so that I can change the design or how the trim voltage is set. This would allow easier testing of a micro controller/digital pot setup if I ever decide to pursue that design. The PCB cost will be somewhat high due to the large size and low volume, but it will pay for itself many times over in ease of assembly and long term reliability. I admire those who integrate this type of individual charging setup on perf board or other more manual types of mounting and connection method, I can imagine the huge amount of work it would take to make every connection and add every component.
I still need to revise some of the trace routing to clean things up a little, as well as all of the labeling however it’s almost ready to send off to the board house and have the first batch made. I will have to do some more testing to choose the final resistor and trim pot values to give the output voltage ranges that I’m looking for. There will be one 16 cell charging PCB per battery box and a total of 6 battery boxes in the car. This was done to give a certain amount of flexibility on the final weight distribution of the car, there will either be 3 front and 3 rear or 2 front and 4 rear depending on how much weight I need in each location.


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## Tesseract (Sep 27, 2008)

rwaudio said:


> ...The board itself will be thicker than average at 2.4mm (vs 1.6mm which is standard) this will give a bit more rigidity and strength to the board since the dc/dc converters are somewhat heavy. The traces will all be 4oz copper for extra current handling....


Interesting project. I don't know if you actually NEED 4oz Cu - I'd think long and hard before I'd go over 2oz (70um) plating thickness - but if you really do need it then I highly suggest these guys: http://www.circuitboards.com/index.php for the board. They do excellent work (and make the boards here in the US!) but are also very reasonably priced. I've ordered heavy copper boards from them many times - they are, in fact, my preferred Heavy Cu vendor. 

But like I said before, I'd think long and hard about whether you really need 4oz Cu. Don't forget you'll have to increase your minimum trace thickness and spacing to at least 10mils for both at this thickness.

Anyway, hope that helps.


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## rwaudio (May 22, 2008)

Tesseract said:


> Interesting project. I don't know if you actually NEED 4oz Cu - I'd think long and hard before I'd go over 2oz (70um) plating thickness - but if you really do need it then I highly suggest these guys: http://www.circuitboards.com/index.php for the board. They do excellent work (and make the boards here in the US!) but are also very reasonably priced. I've ordered heavy copper boards from them many times - they are, in fact, my preferred Heavy Cu vendor.
> 
> But like I said before, I'd think long and hard about whether you really need 4oz Cu. Don't forget you'll have to increase your minimum trace thickness and spacing to at least 10mils for both at this thickness.
> 
> Anyway, hope that helps.


Thanks Jeffrey,

It looks like you are correct, I could get away with 2oz and have a 31deg C over ambient temperature rise at full current. This is a simple (big) board, minimum trace width is 12 mils, same with spacing. 

Thanks for your input, I'll check out that board house as well.


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## rwaudio (May 22, 2008)

Motor is finally in, damn weather, it took longer to chip away at the ice to be able to push the car into the garage than it took to install the motor!!

Took it for a very leisurely drive on 12v and it works like a charm, coupler it's perfect yet but still working on that.


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## Bestpod (Mar 18, 2011)

Hi GUys im a Newby and have 2 early 80s 924 turbos I am toying with electrifying one of them. How are your machines going? I am looking for advice on what I need so following your threads is good info ! Thanks



also has anyone considered body modifications to mount the motor flush to the transaxle (doin away with the torque tube), on 924 board .org there is a NZ rally 924 sporting a rotary engine which has had the trans tunnel lifted to accom the rotary motor. I reckon extending the rear "bell housing" tunnel forward to accom the motor would work, getting it past the Compliance peoplemay be harder but it would sit nicely between the rear "seats".


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## rwaudio (May 22, 2008)

Bestpod said:


> Hi GUys im a Newby and have 2 early 80s 924 turbos I am toying with electrifying one of them. How are your machines going? I am looking for advice on what I need so following your threads is good info ! Thanks
> 
> 
> 
> also has anyone considered body modifications to mount the motor flush to the transaxle (doin away with the torque tube), on 924 board .org there is a NZ rally 924 sporting a rotary engine which has had the trans tunnel lifted to accom the rotary motor. I reckon extending the rear "bell housing" tunnel forward to accom the motor would work, getting it past the Compliance peoplemay be harder but it would sit nicely between the rear "seats".


Hello, I think the 924/944 is a great platform for a conversion. If I was going to try the motor in/around the tunnel route, I would go with a pair of warp 7's end to end (maybe even a trio?!?!) The tunnel would need much less work to get the 7" motors in there vs a 9" or 11" but still give tons of torque/power. That would get the motor weight central and low and give you tons of room up front to mount the battery pack also very low. With motors in the center/rear of the car I probably wouldn't add too much more weight to the back, but concentrate on bringing the front end back in balance.My build is going well, I'm a little behind since a fixed up an '83 gasser before moving back to the electric.Good luck with your build, if you have any specific questions I'd be happy to try and help.


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## rwaudio (May 22, 2008)

I haven’t completed any major milestones lately, however I’ve been working on a lot of little projects.
I temporarily mounted the main battery voltage and current gauges in the center console below the very stylish Sony CASSETTE deck. Just to see how visible they were at different angles for both the driver and passenger. They are pretty bright, so I will have to do something about that on the actual install. Right now I simply have them powered off a 24v wall wart, so it’s shows the voltage and current draw at the meters. The meters obviously match, but they are also configurable and have two built in alarms that could be used for just about anything. Since I will be relying on the Soliton1 for low pack warning and limp mode I don’t need that, but it might be useful to have a high/low current LED as a reminder when I’m at or below 1C on the pack (some sort of GREEN LED) or above 500A (some sort of RED warning LED).

The gauges below the stereo are the only “out of place” gauges that I was willing to add to the car, and they will be individually switched so that when I don’t need specifics I can run without them and they will be turned off. Since I’m behind schedule and hope to get the car on the road this summer/fall I had to skip some of the custom projects to have a hope of finishing. The Arduino based battery monitor/SOC meter will be on hold for awhile. So I need some sort of off the shelf SOC/AH meter so that I have a way of monitoring the pack. (I also want it to drive the stock fuel gauge as a SOC meter) To do that there are basically two choices, one is the Ziva Plus from Australia, or the EV display from Florida. Total cost of the two meters is similar so it comes down to features, the EV display wins there so it’s probably going to be the meter of choice. The one problem is the lack of extra gauge locations in the 944 and as mentioned before, I’m not willing to just mount it anywhere. The new stereo (whatever that might be) should have a clock, so the stock 944 clock should become redundant, it also happens to be a similar shape and size to the EV display without the housing.
[/URL]
I still have to confirm the dimensions, however it looks like it might be workable with minor modifications.
Since I’m keeping the A/C in the car I need a way to power the stock compressor. For simplicity I decided to run it off of the tail shaft of the motor (at least to get me started). This requires a 7/8″ keyed serpentine pulley, I couldn’t find one anywhere, so the best choice was to adapt the stock Porsche crank pulley to the 7/8″ keyed shaft. The easiest way was to use some off the shelf parts and weld an adapter to bolt on the stock pulley.

I’ll get a better photo of the pulley soon, but the whole adapter including key stock was less than $10. Also visible in the above photo is the tach sensor made by Recharge Car. I had planned on making my own tach sensor, however it’s hard to resist the simple bolt on version, especially when it’s not a bad price either. This feeds into the Soliton1 and the Soliton1 outputs a modified signal to drive the stock tach in the car.

I also started crimping some of the main cables, along with the very short A2-S2 cable on the motor. I am using 4/0 awg wire in the motor loop, and 2/0 for the batteries. I was able to get the cables printed at no extra charge, so of course they say electricporsche.ca



I’ve been trying to decide how to mount the commutator end of the motor for awhile now, and after laying under the car for awhile scoping out the options I came up with a plan. There is a plate on the end of the motor that attaches on the bottom to a Bosch Rexroth extrusion that will be mounted to the stock strut brace as well as two larger tapped holes in the frame. Above the motor the same plate will hold the bracket for the Soliton1 and throttle. This is also the first time I’ve fired up the CNC router to make a part for this project. Everything worked very well and the plate turned out as expected. There are quite a few extra holes, but that is simply because it was recycled from a larger plate meant for an LCD tv mount.

And of course I can’t make something on the CNC machine without a little engraving.

Due to the thickness of the plate and the proximity to the tach sensor I had to make a small pocket for the body of the sensor to sit in. This allows the sensor to mount in the stock location on the tail shaft. I will need to get some allen head cap screws to re-install the sensor since the stock bolts interfere with the plate.

The DC/DC converter charging board never seems to be finished. Once I got the previous design finished I did some more testing with the A123 20AH cell and the due to the low impedance of the battery, the current output went through the roof. This is fine for charging one cell, but when I have a string of 96 in series I simply wouldn’t be able to supply enough power to the dc/dc converters.
The solution?
A feedback loop on the trim adjustment of the dc/dc converter that lowers the voltage output to maintain the preset current, and as the cells charge the voltage goes up to maintain current until it hits the CV portion of the charge and then it tops out at the preset voltage. Like one of the previous versions of the charger it will have two stages or settings so that when I plug into 240V the dc/dc converter portion will automatically increase the current output to make use of the extra power. The other change in design was removal of the voltage monitoring system due to the large amount of programing work. This project will be put off until the car is on the road and essentially finished and I have some time to work on it again. Since I still need some sort of LVC monitoring and I’d like to see how the cells are doing I’ve decided to incorporate 2 cell log 8′s onto each charging board. This is made easier by the fact my design is already based on 16 dc/dc converters per PCB which means I just need two cell log 8′s per board to monitor the cells.

The cell log 8′s can easily be removed from their plastic casings leaving a fairly small light weight PCB that just begs to be plug into something other than a wiring harness. (ya I know my picture shows it plugged into a wiring harness, the PCB’s aren’t done yet!)


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## Yabert (Feb 7, 2010)

I really like your few little updates. Nice work!

It was amazing how there's advertising on your car .... I appreciate especially Electricporche.ca on orange cable 2 / 0 ....

One question: Why you don't use straight copper bar on the motor instead use two lugs and a wire?


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## rwaudio (May 22, 2008)

Yabert said:


> I really like your few little updates. Nice work!
> 
> It was amazing how there's advertising on your car .... I appreciate especially Electricporche.ca on orange cable 2 / 0 ....
> 
> One question: Why you don't use straight copper bar on the motor instead use two lugs and a wire?


I had the wire 

Honestly the terminals on the 11HV are WIMPY, there's a reason even the new Warp9 has 1/2" terminals. I had planned for the solid bar, but after installing a temporary 4awg wire to spin up the motor I decided to use a 4/0 wire instead. I'm sure I could get the correct rotation on the bar to sit flat on both terminals but for now it's a wire. The Panduit lugs and crimper work really well though (even if I did a couple extra crimpers per lug vs the instructions.. oops)

The orange wire came from an ebay seller, I wasn't able to track down any orange wire locally without special ordering at insane prices. The printing was included for free which is a cool touch.

I have some time off starting tomorrow so I hope to get all the little things out of the way, including finishing the motor mounting, installing the heater, vacuum pump, gauges, reinforce the transmission mount, clean up some old wiring and remove all the unused fuses and relays, interface with the stock gauges for coolant temp etc. Then prep the car for batteries even though it will be awhile before I have them.


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## rwaudio (May 22, 2008)

I made the local paper, front page of the business section, perhaps it's time for an update 
She got a couple details out of context but it's a good write-up. She also did some of her own research to give a better background to the article.

The first page scanned twice because I couldn't fit the whole length on the scanner.

It's led to inquiries by CBC Radio and interest in having my car featured in the Alberta Pavilion at the Global Clean Energy Congress to be held here in Calgary in early November.

I'm not a tree hugger, but this is the type of interest I was hoping the car would draw and expose people to existing alternative energy sources.

Now to get the damn car finished!!


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## rwaudio (May 22, 2008)

The car has been progressing slowly, work has been busy so I haven't had the time or energy to do all the things I had hoped to have complete by now. There is no drop dead completion date, so I will just keep plugging away and make sure things are done right. Just like everything else in this build decisions are made, then changed, then changed again! I finally have the batteries on hand. It's not the Thundersky that I chose early on, it's not the Headways that I switched to later. The winner is A123 and the 20ah pouch cells. They aren't easy to get, and for a product that's made in AMERICA (or Korea) the easiest way to get your hands on them is from China. The cells test incredibly well though, so I think it's just the right cell for my car and my goals. From the cells I have on hand I will be building a 15.8kwh pack to get me started this should give me 60-100km of range if I drive nicely, or a lot of fun on my 17km commute to work. I'm still working on the details of the connection method but I will be using aluminum blocks/spacers to create the series/parallel connections that I need.










I have been putting off removing the transmission for months since I knew it would be a lot of cramped under the car work to get it out. Finally I bit the bullet and went ahead with the removal, and it turned out to be exactly as expected, not horribly difficult just time consuming and uncomfortable under the car with limited working space. I took this opportunity to strengthen the transmission mount at the same time, a seemingly common fix is to use a two part urethane to encase the stock rubber transmission mount to remove unwanted movement but unlike a steel or aluminum mount it won't transmit all the gear noise to the cabin.










With the transmission out the gas tank removal was very simple and straight forward. With the gas tank out the hatch floor removal was also simple and straight forward. And finally with no hatch floor the transmission installation could not have been easier. I will get the remaining bolts torqued down and the new Stage 8 locking CV bolts installed then the drive train is virtually complete and should hold up to the extra torque from the electric motor.










I did a quick test fit of the locking 3 prong socket that I may use for my charging port, it fits well in the stock filler opening.




















Battery boxes to come!! I also have the coupler back from Charlie of evcouplerconnection.com so I will have to slide the motor forward and reinstall the coupler. This time I will photograph the process a bit better along with the mounting of the A/C, controller, vacuum pump and throttle.

This update was in Draft form so long that many things had changed. As it turns out there is a completion date (or dates)!!! I have agreed to do a small informal presentation at work about the electric car project so it would be really nice if I could BRING THE CAR. Completion date #1 Oct. 12th, the car really only needs to drive there and back.
With the exposure the car has received there is interest in showing it at the Global Clean Energy Congress, completion date #2 Nov. 1st.

If the scan of the newspaper article is difficult to read just click on the link below for an online version.
The Calgary Herald.


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## Spyder.ev (Sep 6, 2011)

Hi Rwaudio,
Really intersted in your build as i am currently buying a Porshe 944 S2 to convert, Few questions if you got time, why did you go for the Warp 11hv against the Warp 9 ? I have been looking around and listening to people and it seems a Warp 9 should be ok, Is it because you intend to have a High voltage pack?
Also Can you tell me How many cells will you put in the Engine compartment, and how will the overall weight balance out?
Im Thinking of using a Warp 9 with Warp-drive controller running to start with 50 200AH Sinolopy Batteries but im not sure how many i will get in engine compartment. 
I really like the idea of losing the clutch and think i will go this way as well. Also would be very interested in your overall weight when finished do you think lighter or heavier than stock...
Cheers hope everything is going to plan.


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## rwaudio (May 22, 2008)

Spyder.ev said:


> Hi Rwaudio,
> Really intersted in your build as i am currently buying a Porshe 944 S2 to convert, Few questions if you got time, why did you go for the Warp 11hv against the Warp 9 ? I have been looking around and listening to people and it seems a Warp 9 should be ok, Is it because you intend to have a High voltage pack?
> Also Can you tell me How many cells will you put in the Engine compartment, and how will the overall weight balance out?
> Im Thinking of using a Warp 9 with Warp-drive controller running to start with 50 200AH Sinolopy Batteries but im not sure how many i will get in engine compartment.
> ...


Hello Spyder.ev I chose the 11HV over the warp 9 purely for performance (300 peak hp). I am using the Soliton1 and will have a 300+ volt pack, this should give me plenty of torque AND horsepower. I will be using a 96S pack of 60ah (3x 20ah) A123 cells. These are small and lightweight and will all fit in the hatch area nicely. This simplifies wiring and will allow me to keep a single pack temperature (I hope) With the 225lb motor, adapter plate/coupler/controller/power supplies for the charger all going in the front I should be very close to stock weight distribution (as it was with a full tank of gas). I might be a bit heavier in the rear but I would prefer the bias to be slightly to the rear than slightly to the front. I'll move things forward if I'm more than 53-55% rear though. 

With a Warp9 and careful planning you could probably get 15-20 cells up front. There is a lot of room in front of the motor where the radiator was removed, there is also a bunch of space beside the motor on the passenger side, the drivers side is fairly full with the steering/brake booster etc. Depending on the controller size, there is also a bunch of room on top of the motor. 200ah cells might not give you a lot of flexibility to use the available space efficiently though. Based on my very light A123 pack I should come in at stock wet curb weight or maybe even slightly under.

Just consider that 50x 200ah cells is well over 600lbs, my pack will be under 300lbs before connecting bars. So unless you lighten the car in other places you will end up over stock weight. So many pieces on the 944 are aluminum or lightweight so not as much weight comes out as you might think.

The other thing to be careful of is the transmission, lots of torque can actually rotate the transmission and put the CV joints out of alignment causing them to break. The urathane fix as mentioned on rennlist.com works well and is cheap, that's what I did to my transmission mount. I don't know anything about the S2's but you would probably want the higher ratio transmission that the turbo's come with to take advantage of the increased torque. 

Good luck with your conversion!


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## shock (Jul 16, 2011)

Thank you for sharing all the details of your build. I have started my own Porsche 944 (83) conversion. You can check out the thread under Technical discussions called "It begins..."

Pulled the transmission out last night. I had not heard of the improvements available for the mounts, thank you for sharing that. Hopefully starting on pulling engine tomorrow.

You are doing a great job with your posts. I am terrible at that, as well as pictures - I know... I know... get better at it, lol. But thank you for all you have done here so far, it will help me quite a bit.

As I get further into the build and make up my mind on motor/controller/batteries I will start a thread that might be useful to others. Right now I'm just stripping out all the unnecessary components. Unlike others, I have no affection for the Porsche interior or the outdated exterior, and I will be re-creating into my version of modern, comfortable and stylish. Flat panel displays, LED lighting, etc.

I am really looking forward to seeing how your car performs when you are done!

Cheers!

Shock


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## rwaudio (May 22, 2008)

shock said:


> Thank you for sharing all the details of your build. I have started my own Porsche 944 (83) conversion. You can check out the thread under Technical discussions called "It begins..."
> 
> Pulled the transmission out last night. I had not heard of the improvements available for the mounts, thank you for sharing that. Hopefully starting on pulling engine tomorrow.
> 
> ...


I don't blame you for wanting to change the interior on the '83! My wifes car is an '83 944 and well I have to say it's hideous compared to the '86. I like the exterior though and with some fresh paint I'm sure I'll be happy with mine.

(one of my main goals is that the car is identical to the gas version in appearance and the missing exhaust pipe and a small emblem is the only tell, the interior won't give away it's secret either)

Good luck with your conversion I look forward to seeing what you come up with, especially for the interior!


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## rwaudio (May 22, 2008)

Well a small update, I had a presentation at work where I agreed to bring/display the car, so I worked night and day for a week just to get it to a drivable state (not finished but drivable) I only had a 32S3P pack (54Ah 105v) so I didn't get a ton of performance out of the 11HV, but it was still an amazing drive!!!! My first real EV grin, so it provided extra enthusiasm for my presentation. The car was as smooth and quiet as I could have hoped for, everything worked perfectly, I was a bit worried about my 12v system since I don't have the dc/dc converter in yet (needs minimum 137v) so I supplemented the yet to be removed crappy lead acid with a 20ah pack of headways and all was well, headlights and everything worked perfectly. On 100v the 11hv peaks out around 3000rpm and power drops off before 2000rpm. Acceleration was still pretty good though because I could still draw upto 1000 battery amps if necessary, (the lack of voltage did limit the conditions where I could coax it into drawing any kind of big current though) it reminded me of driving a diesel.... tons of torque and limited rpm range, but QUIET. I had no problem keeping up with traffic, and had a brief period at around 70mph. I needed 4th gear to have the rpm range to get there though, and I did notice that battery current seems lower in lower gears for a given speed IE. 3rd vs 4th for 55mph. All in all the car was a blast to drive, it's a bit under powered with such a low pack voltage. The presentation went very well there was interest and questions from a large portion of the crowd (made up of many titles from professional engineers, software developers, accountants all the way to admin and shop technicians. (I work for a company that develops control and automation systems for the oil field, service rigs, frac etc). 

Clutchless shifting is a breeze, no issues there. Upshifting is smooth and fairly seamless if you just let it drop into gear (not good for drag racing) down shifting if/when necessary does require an extra second or two but you can see the motor rpm increase as the syncro's match the speed even without touching the throttle. The coupler is good now, Charlie at evcouplerconnection.com did a great job the 2nd time around on the coupler. It was a nice tight fit requiring a rubber mallet to install on the shaft, it's the perfect length and now spins true. Obviously I haven't tested it past 3000rpm but the drive train is smooth and quiet up to that point. I used 2nd and 3rd gear for the trip, with the brief use of 4th above 55mph due to limited rpm. 

I do have a hand full of cells that I believe to have high IR as their "defect" instead of low capacity, two groups had some swelling and got much hotter than the rest of the pack, terminals were fine, but the cells themselves got quite hot. I will pull those groups from the pack and test them, but I can live with 6 or 9 of 96 having high IR for the price I paid as long as the same type of ratio carries forward for the rest of the cells. I didn't expect them all to be as good as real cells and I was prepared for a few issues like this. I probably won't test the car again till I have at least 200v but at that point I think it would make a great daily driver giving enough capacity to get to/from work without needing to recharge and better performance at a lower current draw.

It's been a long time coming and I would like to thank all of those that have provided input, suggestions and answered questions along the way. I still have a lot of work to do, but the Soliton1 worked great, I configured and wired everything with the assumption that it would work and when it came to testing (9:30pm the night before I had to drive it to work) everything worked flawlessly except I still had idle setup, oops! I'm using the start input, tach input, "Valet" input, and LVC input. 
I did have to "learn" how the controller wants to use the start input though since I'm not using the status output light. Turn the car to run, wait for the contactors to engage within the Soliton THEN turn the key to start and release. The Porsche has a safety where you can't go to start twice, IE if you turn the key to start before the contactors click you have to turn it off completely and try again. Good for keeping uninstructed people from driving the car, but not some weird complicated ritual that I would need to do just for me to drive the car. Outputs are Battery current to the oil pressure gauge, Tach to the tach obviously and controller temp to the coolant temperature gauge. I may go with battery voltage instead of controller temp to one of the gauges so that all the basic info is available in the stock instrument cluster without the need for turning on the external digital (don't match the look of an '86 Porsche) type gauges. I also need to order an EV Display to run the fuel gauge and the main unit should fit where the stock clock was. There is a main wiring harness from the Porsche that ran right by the terminal strips on the Soliton1 so I was able to get switched 12v, start signal, and interface with the gauges (except the tach) all with the stock wiring. The ground wire in that group was bad so I had to run a separate ground wire for the Soliton, but once I zip tie/techflex the wiring it should look clean and minimal.

The Mes Dea vacuum pump works perfectly, and it's pretty quiet. When I'm stopped at a light with no other noise I can hear the pump and feel a slight vibration in the steering wheel. It's very minimal though and with the radio on I wouldn't hear the sound, I may have to work on the vibration though, it's very subtle, but it's there. Power brakes work great, the pedal feel is good, I may add a vacuum reservoir to let the pump run longer but less often though. The Evnetics throttle works as expected and pedal feel is good. I'm using the Warp speed sensor from rechargecar.com (bought from Mike at evpropulsion.com who provided great service). It seems to work well with the Soliton1, I haven't been able to hit the rev limiter however the tach is smooth and responsive. 

I'm very happy with the choice of donor car, the 944 drives very nicely as an EV, it's been nice to work on and it should last many many years. I finally have an EV grin! I can't wait to drive it every day.


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## patrickza (Dec 28, 2009)

Congratulations, if must feel like it'll be all downhill from here!

I take it you're running the 20ah a123 cells. What size will your final pack be?


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## rwaudio (May 22, 2008)

patrickza said:


> Congratulations, if must feel like it'll be all downhill from here!
> 
> I take it you're running the 20ah a123 cells. What size will your final pack be?


It was nice to drive finally, I look forward to driving it even more now. The final pack will be 96S3P (288 cells) which should give me 100km range under decent conditions not to mention more power than I really need.


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## Bags (Jun 20, 2010)

You can never have too much power!

Seriously, I was calculating about the same sized pack for my Mazda RX-7, but I would configure it as 48s6p, because this pack would be replacing a 156V lead-acid pack. I already have 156V components. But a couple of questions: What is the "pulse" discharge rate? Do you have any data about the cycle-life, at >1C discharge rates? I'd guess you'll be pulling 2C-3C for average driving, and 8C-10C for hard acceleration.


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## branko (Mar 1, 2012)

rwaudio, here is your countryman from Winnipeg. 
I've got a 944 '87 3 speed auto ready for conversion. Car is not, it's in perfect condition but I am ready. It's an automatic and not very popular for conversions. 
What I found so far is that this transmission needs less than 400 rpm to keep good valving pressure. 
The stall speed is 2800 rpm which will allow higher motor rpm. Also the position "2" will keep it from shifting into 3rd gear (equivalent to 4th manual) so it is like using 2nd and 3rd in manual. Throttle would need to be adjusted to 300-400 rmp idle and beside that only con for this conversion i see would be maybe 20% loss on hydraulic efficiency. It would provide convenience of automatic for my wife as this is her car which mostly I drive especially in winter. 

I am so convinced it would work regardless of what anybody else may say.
So this is not why I am posting this. 

I have seen all your work before I found this forum and I would love to hear your opinion on this: 
Looking at the picture of your 944 rear floor open and the fuel tank removed I can't help but picture two 6-7" AC motors facing one each wheel, connected to drive axles direct. No dif. AC reversible gearhead motors, single brake recovery controller driving both in parallel providing limited slip dif efect. 

I am sure this crossed your mind more than once. Your opinion on this is much appreciated. Would it be even legal?

P.S. I love your SENSORS--->BLUETOOTH--->7" ANDROID TABLET" instrument cluster idea. 

Branko


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## rwaudio (May 22, 2008)

branko said:


> rwaudio, here is your countryman from Winnipeg.
> I've got a 944 '87 3 speed auto ready for conversion. Car is not it's in perfect condition but I am ready. It's automatic and not very popular for conversions.
> What I found so far is that this transmission needs less than 400 rpm to keep the fluid flood the torque converter and valving and it's ready to go.
> The stall speed is 2800 rpm which will allow higher motor rpm. Also the position "2" will keep it from shifting into 3rd gear (equivalent to 4th manual) so it is like using 2nd and 3rd in manual. Throttle would need to be adjusted to 300-400 rmp idle and beside that only con for this conversion i see would be maybe 20% loss on hydraulic efficiency. It would provide convenience of automatic for my wife as this is her car which mostly I drive especially in winter.
> ...


Welcome to the forum, good choice of donor.

When I was calculating my gear ratio's I stumbled across the auto ratio's and I don't think it's a bad choice at all. Like you said 1st and 2nd in the auto should be similar to what I get using 2nd and 3rd and you have the option of 3rd in the auto if cruising at higher speeds. I would recommend a controller like the Soliton1/Jr since it already has what you need to control the idle and it works very well. 

If you were to remove the tranny all together there is a lot of room back there once the gas tank is out. A dual AC setup with the right gear reduction would fit and probably work well, but once you had a pair of AC motors and controllers you could probably do a DC conversion with 3x the power or 2x the range.

Given my experience with the car I would suggest keeping the auto and doing a simple conversion like mine (of course I would because that's how I did it)....

I think you would either need deep pockets or cheap access to a CNC machine shop to make the dual AC set up worthwhile. I've drooled over Mate Rimac's configuration with the controllers/motors/transmissions in a sweet package, bolt that up to some modified CV's in a 944 and you are off and running.

I can't take credit for the Sensors/Bluetooth/Tablet idea, the hardware and idea come from a few people on here, I did want something like this when I started, but don't have the software skills to do it myself. Luckily EMW is filling that void for a fair price. 

Do you have range and performance expectations? That can help narrow the choices on what would work best for you.
Good luck with the conversion.


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## branko (Mar 1, 2012)

Thanks for replying to my message. 
I will check out Mate Rimac's system. We have few CNC mills and lathes where I work so that would not be a problem. The problem is that I like simple solutions which is how you did it. 
As for expectations, I don't have special expectations. Anything is I think better than 2.5 N/A automatic. So much noise for so little power by today's standards. At least the conversion would be quiet. 
I don't think I went for more than 50 km in a day in 4 years with 944 as a daily driver.
For sure I would need Warp 11 or double 9 as I still have power steering pump to run. This could get swapped to manual later if it becomes trouble. It is drivable without the steering pump running. It's hard but it's possible to test the efficiency with and without power steering.
A/C is also not necessary. I could keep it there ready to go without the belt and slip the belt on for those one or two weeks max each summer when it helps.
Heat in winter is as you know a problem. Not as much for feeling cold as much as for keeping fog off the windows.
I need to spend some more time researching battery charger and dc-dc converter for 12V system and will start soon putting together bill of materials for the project.
Branko


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## rwaudio (May 22, 2008)

branko said:


> Thanks for replying to my message.
> I will check out Mate Rimac's system. We have few CNC mills and lathes where I work so that would not be a problem. The problem is that I like simple solutions which is how you did it.
> As for expectations, I don't have special expectations. Anything is I think better than 2.5 N/A automatic. So much noise for so little power by today's standards. At least the conversion would be quiet.
> I don't think I went for more than 50 km in a day in 4 years with 944 as a daily driver.
> ...


I would agree with the simple system as being potentially better. Since your range requirement is modest you could get away with a 200-300v pack of A123 20ah pouches in a 3P (~56-58Ah) configuration. If going with 200v then a regular warp 11 would work, if 300v then a warp11HV. In either case I would recommend the Soliton1.

I don't think you could do a pair of 9's end to end unless you highly modified the torque tube to get one of the motors as far into the tunnel as possible. Even then I doubt you could run any accessories off the tail shaft as there wouldn't be room. I can say that an 11HV does fit nicely though!

Decide on your battery pack first, then find a charger/dc/dc converter that will work with it.
EMW has a nice charger kit (or finished) for a good price.
There are a number of power supplies that will work as a dc/dc converter.
IE a few of the Mean Well ones, including the one I modified for dual voltage.


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## branko (Mar 1, 2012)

Here is an old 944 conversion with two 9's belted together.

http://www.jstraubel.com/944EV/EVproject.htm

What is space/weight of Headways vs A123's? Did you switch to A123 cell for better design reasons or because you came across the cheap stash of pouches.
Headways seem very elegant when packaged with spacing for air circulation for even heating/cooling. A low temperature self-limiting heat trace cable could run in between cells.


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## rwaudio (May 22, 2008)

That's actually a pair of 8's belted together, I'm not saying a pair of 9's is impossible but I don't see how it could be done easily.

I went with the a123's for one reason only, high power output with the lowest voltage sag of any cell I tested. The headways are easier to work with, but the a123's are more compact lighter and higher power.


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## rochesterricer (Jan 5, 2011)

This one has 2 Warp 9's:

http://www.evalbum.com/3547


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## rwaudio (May 22, 2008)

rochesterricer said:


> This one has 2 Warp 9's:
> 
> http://www.evalbum.com/3547


That's interesting, too bad they don't have more pictures. From the picture they do show they aren't stacked like JB's 8" motors. They mention being connected tailshaft to input shaft with a chain, does that mean one motor is offset to one side and in front of the other?? 

If someone wanted a pair of 9's I would look at the prejoined Kostov motors that are available, first of all they are cheaper than two single motors and already joined, along with being potentially shorter and massively cheaper than two motors custom joined.

This would put the tailshaft of the front motor (if it has one) just behind the front bumper, this would make it virtually impossible to accessories unless you got really lucky with the final placement.

For reference a clutchless 11HV moves the accessories back about 3-4" from the stock location on the gas engine. A/C lines are long enough to work without modification, I'm not sure if the P/S would still work if used since mine went away.


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## branko (Mar 1, 2012)

With HV motors available I don't see much reason to use two motors. Except you get two internal fans working. It should have benefits on low speed.
123's should be easier to use with tabs then what you had to do with the tabless. 

The 944 from rochesterricer's link is a masive $$$ conversion. I still don't know how he seats 4 adults.


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## rwaudio (May 22, 2008)

I haven't been updating this thread much, so to get myself back in the habit here are the results of all of my measuring work to group the A123 cells.

In my testing I came up with an average capacity with a 2C discharge to 2.25v of 18.666....Ah this gives me a 3P average of 56Ah, so I grouped the cells accordingly within 0.01Ah.

I've been assembling modules finally and put one of them to the test to see if all of this work is actually worthwhile, it seems to work pretty well so far!

The cells were essentially top balanced, as each cell group was charged individually to 3.65v with a c/20 termination. The pack as a whole was then cycled once, recharged to see if it remained in balance then discharged.

The discharge graph of the four cells as produced by the PL6 is attached.

At a 40A discharge ~0.71C I recorded a pack capacity of 57.488Ah for module 3, the true test is if all 24 modules come in at +/- 0.1Ah then all of this will be worthwhile.


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## rwaudio (May 22, 2008)

First test fit of the tablet running EMW EV Dashboard.

This is one of those things where I got lucky, I knew the size was just about right when I bought the tablet, but it's absolutely perfect! The screen is 100% visible in any gear but 3rd (and 1st but I won't be using that anyway) and in 3rd the shifter only covers the bottom right corner so I will make the lower right gauge a less frequently monitored one.

The tablet is at a nice distance and angle and should be within reach for easy use, at first I thought a larger tablet would be nice but this actually fits the space very well and since the seating position is quite close the small tablet looks to be the perfect size.

I did have to remove the back cover of the tablet and move the dock connector and audio output jack so they can actually be used, but it fits nice and hopefully it's a good angle where glare won't be too big an issue in everyday use. I have an anti-glare screen protector to go on so that should help as well.


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## JRP3 (Mar 7, 2008)

Nice OEM look


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## PatricioIN (Jun 13, 2008)

rwaudio said:


> First test fit of the tablet running EMW EV Dashboard.
> 
> This is one of those things where I got lucky, I knew the size was just about right when I bought the tablet, but it's absolutely perfect! The screen is 100% visible in any gear but 3rd (and 1st but I won't be using that anyway) and in 3rd the shifter only covers the bottom right corner so I will make the lower right gauge a less frequently monitored one.
> 
> ...


Looks great.. you should be able to find extenders for the docks so you don't have to disassemble and move what you have..


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## rwaudio (May 22, 2008)

PatricioIN said:


> Looks great.. you should be able to find extenders for the docks so you don't have to disassemble and move what you have..


The issue is the jacks are on the left/right of the tablet and there simply isn't room to plug anything in to them. I moved them simply so that I can use them. I can't stand the look of a hack job with wires hanging out etc.


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## rwaudio (May 22, 2008)

I don't update this thread that often, but I've made quite a bit of progress, I'm driving the car now, with no instrumentation so I keep it to about 50% of my theoretical range or less just to be safe. I have just under 1/2 the final pack in the car which is 145v/57Ah worth of A123's. 

I took the car down to get weighed to compare the current weight to my theoretical (but mostly measured) calculations.
Current weight:
Front = 560Kg (46.3%)
Rear = 650Kg (53.7%)
Total = 1210Kg (2662lbs)
My spreadsheet says I should be at 2660lbs based on the size of the battery pack installed. So I'm dead on with the weight, but I'm a bit off on the front/rear distribution. To keep complex calculations out I added and subtracted weight from the front/rear with the assumption that what I put back was in basically the same place as where I removed it from, this is obviously slightly off. The 11HV's center of gravity is significantly further back than the stock ICE with accessories was. The battery box is also further back than the gas tank was.










I had expected my final weight distribution to be around the ratio I'm currently at, I don't have a significant amount of weight to add to the front, some fans for the AC, the heater's and pump, a heat shield between the motor/controller, but I still have ~165lbs of batteries to go in the back, plus a slightly heavier charger.










This gives me a theoretical final F/R weight balance of 43.5/56.5, definitely not horrible especially for a rwd car but I might look at bringing some weight forward. The driving position does not affect the ratio as it was exactly the same with me in the car. I'm on track for a finished curb weight of ~2800lbs, the 12v lead acid still needs to come out and I need to add 165lbs of batteries plus a few other small things.










I'm not doing too bad though since the stock curb weight was right around 2790lbs but with a 50.7% front/49.3% rear weight distribution. (when finished I will have double the HP and torque of the 944 I started with) In real driving the torque from the 11HV makes an insane difference, 1st gear with the NA engine and turbo tranny was a bit too tall, with the 11HV 2nd gear is almost ideal at 1000A. 

I also installed the 20A receptacle in the fuel filler that I will use until I get 240v in the garage, then I will likely switch to a J1772 connector.


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## Joey (Oct 12, 2007)

Is there any room left in the front to add any of the remaining batteries? Sounds like there isn't any room, at least not without major rework, if it is even possible. It doesn't sound too bad, though. You would probably have to be cornering hard at higher speed to notice a few percent difference.


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## rwaudio (May 22, 2008)

Joey said:


> Is there any room left in the front to add any of the remaining batteries? Sounds like there isn't any room, at least not without major rework, if it is even possible. It doesn't sound too bad, though. You would probably have to be cornering hard at higher speed to notice a few percent difference.


The front is actually pretty empty, however for wiring and temperature issues I don't want to split up the pack. I may move the charger to the front but I'd have to weatherproof it or put it in a suitable "box" that still allows me to air cool it.

I'm still not as heavy on the back as a 911 though, I'm sure if I took it to a shop that was familiar with both 944's and 911's they could set up the suspension for a rear heavy 944.


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## Baldbruce (Aug 1, 2011)

Thanks for posting your weight RW (944 that is ;-). My very crude measurements are very very close to yours in percentage with mine being a bit heavier because of the battery differences. I estimate roughly 1350 front and 1600 rear or roughly 46%/54% ratio.

Looking awesome!


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## rwaudio (May 22, 2008)

Baldbruce said:


> Thanks for posting your weight RW (944 that is ;-). My very crude measurements are very very close to yours in percentage with mine being a bit heavier because of the battery differences. I estimate roughly 1350 front and 1600 rear or roughly 46%/54% ratio.
> 
> Looking awesome!


Thanks Bruce, I've been driving the car all week and it's just awesome! Gave a few co-workers an EV grin as well. I normally drive an '07 Infiniti G35 and although it has tons of power (306) and a decent amount of torque (~275) the auto is always in the wrong gear and it typically has to shift down 2 gears for anything to happen, it's annoying. In the Porsche I use 2nd or 3rd so I'm always in a gear with useful torque and so much of it. The driving experience is so much better.


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## rwaudio (May 22, 2008)

A bit of data/experience for other 944 converters or others using the 11HV in a non-race car type conversion. 

3rd gear has become my normal driving gear, I start in 3rd which is a 4.725:1 overall ratio, using the Soliton1 (motor/battery current set at 1000A).
There is plenty of torque off the line and acceleration is better than a stock 944, (especially since I reach 100km/h ~60mph without shifting) there is no tire squeal or noise I just surge away from all the other cars.
The car cruises beautifully anywhere between 50-100km/h in 3rd and I never have to shift. (max speed limit on my new commute is 80km/h)

The biggest difference I've found between the 944 @ 130hp/300ft lbs and the Infiniti @ 306hp/275ft lbs is that the power/torque is actually in a usable place with the 944, it's fun, it's accessible and I don't have to rev to 7500rpm 
just to use the power band.

This is all with 145lbs or $2640 worth of batteries. Just like Jack R. said, with this type of set up there really isn't much reason to go lead acid.

If the NA transmission can stand up to the torque I believe that 3rd gear would be the perfect starting gear when using a 1000A controller, with a 5.670:1 overall ratio it would be about half way between my 2nd and 3rd gears. With a 1200 or 1400A controller I believe that my 3rd gear 4.725:1 would be perfect.

This should only get better as I increase the voltage of the battery pack (currently only 44S ~145v) but it's been an incredibly enjoyable 370km so far.


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## drgrieve (Apr 14, 2011)

Thanks for the feedback - it would seem to be a common theme that an EV really only needs two gears and reverse if you have a decent setup.

Will be interesting to see how your car goes when your battery pack is completed. 
When are you finding the torque dropping off at the moment - around 80 kmph?

Any idea on your current 0-100 time?

Cheers


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## rwaudio (May 22, 2008)

drgrieve said:


> Thanks for the feedback - it would seem to be a common theme that an EV really only needs two gears and reverse if you have a decent setup.
> 
> Will be interesting to see how your car goes when your battery pack is completed.
> When are you finding the torque dropping off at the moment - around 80 kmph?
> ...


Torque drops off between 90-100, I'm looking for a good place to try a 0-100 run. Anyone know if there are any good android apps to capture a "0-60" time? My speedo is a bit off at that speed so I'd rather let the GPS in the tablet do the work.


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## Bags (Jun 20, 2010)

I guess you are currently configured at 44S3P. That means pulling 1000A is more than 16C. 

Do you have concerns about heat and/or lifetime? And will you still have concerns if you double the battery pack?

Do you limit the Soliton differently in normal vs. "sport" usage? In my car (old 1200A Raptor controller (x2)), when it was running, it was hard for me to keep acceleration gentle enough to only draw 600A or less, and yet accelerate like an ICE car.

Where did you get these cells for $20/each?


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## TEV (Nov 25, 2011)

Try " Car Performance" free version


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## Bowser330 (Jun 15, 2008)

Any chance we could get a video of the acceleration?, some data on your 0-60 would be nice to see (as you mentioned).




rwaudio said:


> A bit of data/experience for other 944 converters or others using the 11HV in a non-race car type conversion.
> 
> 3rd gear has become my normal driving gear, I start in 3rd which is a 4.725:1 overall ratio, using the Soliton1 (motor/battery current set at 1000A).
> There is plenty of torque off the line and acceleration is better than a stock 944, (especially since I reach 100km/h ~60mph without shifting) there is no tire squeal or noise I just surge away from all the other cars.
> ...


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## galeson (Oct 25, 2009)

For your 0-100 you could use the log file on the Soliton and just use the rpm at which you cross 100. That way you can see other useful information at the same time.


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## rwaudio (May 22, 2008)

Bags said:


> I guess you are currently configured at 44S3P. That means pulling 1000A is more than 16C.
> 
> Do you have concerns about heat and/or lifetime? And will you still have concerns if you double the battery pack?
> 
> ...


16C is well within the peak limits of these cells, heat does not seem to be a problem. When I double the pack it will be 96S3P so the load on the cells will not go down, the power will simply go up. (all depending on how I drive of course) I don't have any limits on the Soliton1 yet, I will be doing some sort of valet switch that will do that in the future. I can easily drive keeping the battery current below 300-400A but it's more fun with short bursts in the 800+ range.

The cells are from China, they are the short tab A123's. Landed cost including shipping/duty/tax was $20/cell. They are working well so far.



TEV said:


> Try " Car Performance" free version


Thanks I'll give that a try!



Bowser330 said:


> Any chance we could get a video of the acceleration?, some data on your 0-60 would be nice to see (as you mentioned).


I tried to take a video however my little canon doesn't do well with the glare, I'll give it another try under more forgiving lighting conditions.

Based on a Soliton1 log file and some calculations using that, during this mornings commute I used up 23Ah (3.258Kwh) over a distance of 16.2km for an average wh/mile of 321.8 which isn't bad based on my rather lead foot. I was in no way trying to conserve energy, it was a very enjoyable drive!

Car needs a wheel alignment still and it's running on some 40psi staggered wheels 8" rear, 7" front, I can't remember the tire size I'll update it later.

Excel sheet attached, headings in Italics are calculated values, temperature was ok, the Soliton1 is currently air cooled.

the Excel sheet won't attach in a zip, I'll host it on my site and link later.


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## rwaudio (May 22, 2008)

galeson said:


> For your 0-100 you could use the log file on the Soliton and just use the rpm at which you cross 100. That way you can see other useful information at the same time.


I don't think I have a straight 0-100 full throttle run yet, and I'll have to figure out what RPM = 100 (or 96.5 for a 0-60mph time) Gear ratio and tire size might be the easiest.


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## danh818 (Dec 14, 2011)

Great job RW!! It's so cool to hear that your 944 is on the road and driving regularly. 

Thank you for posting your gear preference and ratio. This is very promising news, as my 4.86:1 first gear is quite similar. 

It may not be of much use to you now, but I came across a great page regarding corner balancing and weight distribution for 944 spec racing. http://www.944spec.org/944SPEC/technical-articles/171-corner-balancing


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## rwaudio (May 22, 2008)

I finally had the chance to do a 0-60mph run, I was at around 60% SOC, batteries were at ambient (25C I hadn't driven the car for a couple hours), tires were cold so I launched gently before getting on the throttle. In those conditions I recorded a 5.0 second 0-60 time which is simply awesome in my eyes. With a full charge, a warm pack, and warm tires and a more aggressive launch I shouldn't have a problem getting into the 4.7 - 4.8 second range, maybe even lower since I'm adding 9 more cells shortly.

Currently I have 92 cells (74 CALB CA 60's and a block of 18S4P A123 pouches) motor current at 1000A, battery current at 750A, slew rate at 2500A/s. I have no idea what the pack sagged to or anything like that. It was in 2nd gear, no shifting.

For reference a stock '86 944 will apparently do 0-60 in 8.8 seconds.


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## Joey (Oct 12, 2007)

rwaudio said:


> I finally had the chance to do a 0-60mph run, I was at around 60% SOC, batteries were at ambient (25C I hadn't driven the car for a couple hours), tires were cold so I launched gently before getting on the throttle. In those conditions I recorded a 5.0 second 0-60 time which is simply awesome in my eyes. With a full charge, a warm pack, and warm tires and a more aggressive launch I shouldn't have a problem getting into the 4.7 - 4.8 second range, maybe even lower since I'm adding 9 more cells shortly.
> 
> Currently I have 92 cells (74 CALB CA 60's and a block of 18S4P A123 pouches) motor current at 1000A, battery current at 750A, slew rate at 2500A/s. I have no idea what the pack sagged to or anything like that. It was in 2nd gear, no shifting.
> 
> For reference a stock '86 944 will apparently do 0-60 in 8.8 seconds.


That is properly quick. Great job. I think you will be a couple seconds quicker than me. Do you think the transaxle is up for the load?


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## rwaudio (May 22, 2008)

Joey said:


> That is properly quick. Great job. I think you will be a couple seconds quicker than me. Do you think the transaxle is up for the load?


It should be, it's the transaxle out of a 944 turbo and it's not uncommon for those guys to use it with LT1 or similar V8's, up to around 400hp and 400ft-lbs, some have more power but that seems to be the safe range.

Now shooting for 4.5 seconds


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## rochesterricer (Jan 5, 2011)

Nice! Was that all in one gear, or was there shifting involved? IIRC, you don't have a clutch right?


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## patrickza (Dec 28, 2009)

Very impressive!

The best thing we can do to convince the rest of the world to go electric is to burn some rubber


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## DavidDymaxion (Dec 1, 2008)

Nice! I'm impressed you could pull that much current from 60 AHr batteries.



rwaudio said:


> I finally had the chance to do a 0-60mph run, I was at around 60% SOC, batteries were at ambient (25C I hadn't driven the car for a couple hours), tires were cold so I launched gently before getting on the throttle. In those conditions I recorded a 5.0 second 0-60 time which is simply awesome in my eyes. With a full charge, a warm pack, and warm tires and a more aggressive launch I shouldn't have a problem getting into the 4.7 - 4.8 second range, maybe even lower since I'm adding 9 more cells shortly.
> 
> Currently I have 92 cells (74 CALB CA 60's and a block of 18S4P A123 pouches) motor current at 1000A, battery current at 750A, slew rate at 2500A/s. I have no idea what the pack sagged to or anything like that. It was in 2nd gear, no shifting.
> 
> For reference a stock '86 944 will apparently do 0-60 in 8.8 seconds.


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## rwaudio (May 22, 2008)

rochesterricer said:


> Nice! Was that all in one gear, or was there shifting involved? IIRC, you don't have a clutch right?


That was 2nd gear all the way, I'd have to add a second or two if a shift was required, clutchless shifting is easy and smooth, but not fast.
The overall gear ratio is 6.949:1 and I hit 60mph at 5600rpm, I have the Soliton set to cut off at 6000rpm. I'm pretty sure I only have 225



patrickza said:


> Very impressive!
> 
> The best thing we can do to convince the rest of the world to go electric is to burn some rubber


I agree, I'll have to see what the car does under ideal conditions, if I was able to get down to 4.4 seconds I would have cut the 0-60 time in HALF.... that would mean something to the ice guys!



DavidDymaxion said:


> Nice! I'm impressed you could pull that much current from 60 AHr batteries.


These CALB CA's seem to do very well, they aren't quite A123's but I'm pretty happy with them so far. My continuous current is between 0.5 and 1C, so 5 second bursts once in awhile will hopefully not significantly affect their life span.

One day I may try a single 0-60 run at 1000 battery amps and see what happens. I have new suspension on the way and 9 more cells to install, I won't try it until all of that is sorted out.


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## rwaudio (May 22, 2008)

As always with this thread it's way too long between updates.

So what's new?
Everything? That should about cover it.

What's the same might be a better question.
The heater is the same, ya same heater!

Technically the CALB's are also still the same, however they are scheduled to be swapped out as well.

Like many others on the forum, I found a Chevy Volt battery pack for a very good price, it's from a 2012 and at $1200 it's pretty hard to say no. (Ya I know, lower potential cycle life than my CALB's)

The Volt pack is the exact same capacity as my CALB pack, however it's at a voltage that should work better with my DMOC645 and Siemens motor. 

Ya those haven't been mentioned in this thread before either. The car is now sporting the Azure Dynamics drive system with the DMOC 645 inverter and Siemens 1PV5135 motor.

What else is new?
The charger, now a Brusa NLG513 (with a 2nd one waiting to be installed)
The DC/DC converter, now a TDK which I believe also came from the Azure system. Water cooled and OEM quality.
Vacuum pump, while technically not installed yet I have the Azure version as well.
Wolftronix DMOC Adapter, similar to the GEVCU it connects to the throttle and all that and sends the CAN messages to the DMOC to drive the car.

While I need more data the early thoughts on AC vs DC (Siemens vs Warp), the Warp 11HV was a raw torque monster, I'd liken it to an American V8. The Siemens is much smoother and more refined, quieter and pleasant for a daily driver, more like a German straight 6. I'll admit I do miss some of the power, but the silky smooth acceleration along with regenerative braking won me over for a daily driver.

If I was building something for autocross/drag racing or similar, it would be the 11HV without a doubt, but if you want to drive it every day with spirited but not fast driving, being stuck in traffic and daily life hands down the AC motor wins.

I'll update the various different changes in more detail as I take appropriate photo's and describe the before and after.


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## JRP3 (Mar 7, 2008)

I was not aware of the Wolftronix adapter. (Actually, after searching some threads, it seems I was aware of it, but completely forgot about it  ) Nice to know there is a non Jack Rickard option  How do you like the unit?

Do you have 0-60 time comparisons between the Warp and the Siemens setups?


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## rwaudio (May 22, 2008)

JRP3 said:


> I was not aware of the Wolftronix adapter. Nice to know there is a non Jack Rickard option  How do you like the unit?
> 
> Do you have 0-60 time comparisons between the Warp and the Siemens setups?


I love the Wolftronix unit, I'm the first beta tester, and 2nd unit in a vehicle so we are working through some bugs and other small things, however in the near future I should be able to make a fair 0-60 comparison.

My current dashboard is attached, and works very very well.

The Wolftronix has all the same capabilities of the GEVCU but in a smaller and more controlled ecosystem meaning tested firmware will work, there will be less firmware vs hardware issues and generational incompatibility. The other side of it is slower development and much lower future compatibility with things like the Brusa/Scott drive/Rinehart and other brands of inverter, etc.


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## rwaudio (May 22, 2008)

Early impressions and information about the Chevy Volt battery:

The build quality and system design are impressive. Disassembly is easy for one person using very basic tools. 

Some of the included "extras" one might not consider:

The front block (if not damaged due to front end collision) has a pair of Panasonic 120A 400V relays (AEV14012). good for main contactors.

There are a trio of Panasonic 10A 400V relays (AEV31012) which are good for precharge and accessory switching, heater/dc-dc/precharge etc. These are PCB mount, not screw/terminal mount so not as easy to work with.

Precharge resistor, pair of series resistors making a 25ohm high power resistor.

Fluid heater, 68ohm resistive heater on the main input (one side may be difficult to connect to, it's the weird connector you see at the input, but the other is the 0.75" barb used in the rest of the pack)
This translates to about 1300-2300 watts at 300-400v respectively, or 1850 watts at nominal pack voltage.

There are a couple of quality 600v 15A fuses (KLM-15), the holder is likely too difficult to reuse, but these are the fuses you should have protecting HV accessories!

If you plan to use this pack in it's high voltage configuration these parts are a very usable freebie that adds to the already exceptional value of this pack going into a conversion. 

The BMS appears to be of good quality and design, however making it work might be the most difficult aspect of the Volt battery. I plan to try and implement the low and high voltage flag that others have talked about. Getting voltage and temperature would be nice but I wouldn't hold my breath.


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## steelneck (Apr 19, 2013)

How much did your kWh/100km (or mile figures) change when going from Warp to Siemens?


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## rwaudio (May 22, 2008)

steelneck said:


> How much did your kWh/100km (or mile figures) change when going from Warp to Siemens?


The data I have so far doesn't portray a fair transition. The first firmware version of my DMOC controller had me hard wired in Econo mode. I was only able to use a little over half power. It was a good experience though, other than complaining that I don't have full torque the car was still nice to drive and perfectly acceptable in traffic, no issues with top speed or anything. So I will configure an "econo" switch that gives me 3 settings, Econo/Normal/Sport which should help me extend my range when desired.

Everyday driving with the Warp was 300wh/mile (3000lb car), conservative driving was 275wh/mile. Aggressive driving was 325-350wh/mile easily.

Forced Econo mode with the Siemens was 235wh/mile in basically the same to/from work drive without regen. With regen it dropped to about 210-215wh/mile. I now have a portion of full power back, so usage is up to about 240wh/mile with more power and regen. When I get full power available I'm guessing conservatively at 250-270wh/mile. But the key is knowing the car is capable of low 200's in mixed driving if I'm very gentle with the throttle. 

Because of the fairly low energy usage the heater seems to take a larger portion of the total. I'm still working out the settings to get enough heat without being wasteful but the increase in wh/mile is very significant. Lowest run with heat is 300wh/mile, but more typically 320+wh/mile. That's not horrible, but it's not really cold yet, and almost 1/3 of my energy use goes to heat. I expect that to increase as the temps decrease.

In short with the AC driving experience if I end up at 250wh/mile for normal driving I'll be exceptionally happy. Even 350wh/mile with comfortable heat will be better than my estimates.


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## Yabert (Feb 7, 2010)

Nice little update.
It's always interesting to see your progress and all the good explanation who come with.
Also, thanks in advance for the job you will done on the Volt battery


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