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Porsche 944 conversion DC/LiFePO4

79K views 95 replies 29 participants last post by  Yabert 
#1 · (Edited)
Well, I signed up here a couple years ago, and this is my first post, but really it's the first time I have something to share with the community. After reading thread after thread, toying with a budget, trying to come up with the perfect donor car my conversion is about to begin.

I've decided on a 1986 Porsche 944.
It could use a little bit of body work, but it drives and handles amazingly well (for a gas car!).

The conversion will start as soon as the gas tank is empty, but it will probably be a slow road just like many of the builds I've read about.
I've gone back and forth trying to decide on motors/controllers and batteries (batteries being one of the hardest).

But I think I've almost narrowed it down to a realistic parts list:
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.

If you made it this far I'm sorry my component choices are somewhat average or mainstream but it's hard to beat what seems to work, I would have loved to go AC or use a pair of motors but reality wins and this is most likely what will end up in my first EV.

With the "big 3" decided, there's only the small things to worry about,
Heater (ya I'm up in Canada, this isn't optional) I've ordered a fluid heater for testing. I would rather not hack up the dash to put in a ceramic heater in.
Air conditioning, it came with the car, it's going to stay with the car, however it will be powered by a dedicated motor because it won't be used that often, so the only penalty is the weight I carry around the rest of the year. To power it I'm looking at "re-using" the stock alternator and doing something like this: http://www.alternatorconversions.com/ the alternative is a treadmill style motor.
DC/DC converter well as my name might imply audio is important, so I will most likely run dual dc/dc converters plus the stock battery. The 2nd dc/dc converter will allow me to have a completely isolated power system for the stereo. Both will be made from common 75-150watt brick style dc/dc converters in modules that give me the peak currents that I'm looking for. Most likely 45A for the stock electrical and 80A for the stereo.
BMS after looking at tons and tons of systems, most of them very expensive, while they may be good I see the BMS as an insurance policy for your pack, something necessary but affordable. Well that leaves only one, MiniBMS! dimitri expect an order in the spring :) I will be doing some of my own guages, so I already need to run a wire from each cell to a 48 channel volt meter, so the centralized MiniBMS should be easy to install at the same time.
Vacuum my step dad is a VW mechanic, and I've read that some VW's have or had electric vacuum pumps, I'll have to double check this and ask for his recommendation.
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.
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 appologize I forgot this members screen name)

That's it for now, I think I've addressed the main requirements. If anyone out there has tips/recommendations/advise I would be happy to hear it. I have lots of automotive experience, as well as electrical but this will be something new for me. I hope the journey is as rewarding as the outcome.








Needs some work, but not bad, and the interior is mint!

 
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#4 ·
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.
 
#3 ·
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
... 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)
 
#5 ·
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.
 
#6 ·
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!
 
#8 ·
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!

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.
 
#10 ·
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.
 
#11 ·
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.
 
#15 ·
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.
 
#16 ·
Duct tape and bondo will soon sort that out.;):D

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.
 
#18 ·
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.
 
#19 ·
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.
 
#23 ·
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.
 
#25 ·
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?
 
#29 · (Edited)
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?
 
#28 ·
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?
 
#35 ·
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.
 
#36 ·
...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.
 
#38 ·
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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#39 · (Edited)
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".
 
#40 ·
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.
 
#41 ·
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.
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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!)
 
#42 ·
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 ....:D

One question: Why you don't use straight copper bar on the motor instead use two lugs and a wire?
 
#43 ·
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.
 
#44 ·
I made the local paper, front page of the business section, perhaps it's time for an update :D
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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#45 ·
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.
 
#46 ·
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.
 
#47 ·
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!
 
#48 ·
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
 
#49 ·
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!
 
#50 ·
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.
 
#53 ·
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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