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Electric Porsche

167K views 393 replies 52 participants last post by  Joey 
#1 ·
After 10 years, I'm finally able to begin my electric car conversion. My goals are 0-60 MPH in < 8 seconds, 100 mile range (60 is an absolute min) at 80% dod, >80 mph top speed, and 4 seats.

I've narrowed the donor car decision down to two: Porsche 944 or Porsche 911/912. I would prefer the 911, but not at the price they seem to be selling for in my area, $14 -20 k USD (1978-1989). The 944 goes for between $1,000 - $5,000 (1983-1987).

For components I don't think I will stray too far from what a lot of people have been doing:
9 inch Warp - keeping the clutch and flywheel
Soliton Jr, or Soliton1
56 cells at 130 aH CALB or 48 cells at 180 aH
Manzanita 20 - The idea of long recharging times (12 hours) doesn't bother me
Battery monitoring and instrumentation - not selected yet

I'm thinking that the batteries will be the system bottleneck and any money I can squeeze from the bugdet should go there. Not sure how many will fit without messing up the weight distribution too much.
 
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#373 ·
I've been working on getting the cooling components into the car: a blower for the motor, and a water loop for the soliton. I made a rack to fit in the cavity of the rear bumper.

Vehicle Auto part Car Automotive exterior Wheel
Automotive exterior Bumper Auto part Vehicle Wheel


There are a lot of curves on a car, and this is the best I could manage to get everything to fit in the limited space I have left.
Automotive exterior Pipe
Mechanical fan Computer cooling Technology Electrical wiring Electronic device


Auto part Vehicle Engine Suspension Automotive engine part


There is a gap where the tailpipe once lived. I'm going to try a foam and fiberglass composite plug to fill the void.
Floor Wheel
 
#377 · (Edited)
I pulled the motor so that I can paint my battery racks and replace my brushes. Turns out the old brushes were pretty well spent - after 3500 miles. I would say the H49 brushes are definitely not suited for street use. I hope the H60 hold up better.
Technology Cable Auto part Electronic device Wire

The outer set of 4 brushes had significantly more wear than the inner set. The length of a new brush is 1.5 inches (from the top to the short side of the radius). The outer brushes were 0.85 inches and the inner set was 1.1 inches.

The other issue is I found washers on two of the brushes between the copper bar and the pigtail terminal of the brush. I took the washers out, because hardware does not belong in the electrical path.

*Edit: In the picture above, from left to right - new H60 brush, used H49 outer brush, used H49 inner brush. Looks like the easiest way to tell the H49 from an H60 is the terminal on the pigtail. H49 use spades, and H60 is a through hole.
 
#378 ·
Beautiful work on your car!!

I had a great time reading almost the entire thread this weekend... I have just started a build that is using very similar equipment to yours, though with 67 160Ah cells and driving the front wheels. I have the exact same goals as you do too, so it was reassuring to see your final results almost exactly mirror what I could predict with any of the various simulations out there.

Here's my blog if you want to see my progress.
http://1996-civic-ev.blogspot.com

Thanks for sharing all of your build progress, and I hope to see more updates!!
 
#379 ·
I painted my rear racks and got them into the car. The rust came off with sanding and wire brushing.

Furniture Wood
Product Table Furniture Metal


I installed some plastic edge trim on the raw metal edge of the box, to keep the nylon strapping from chaffing.
Vehicle Car Auto part Engine Trunk
Technology Auto part Electronic device Vehicle


On the upper rack, I used draw latches to hold the cells securely.
Automotive exterior Bumper Table Chassis Auto part
Revolver Trigger Fashion accessory


I should have painted these boxes a long time ago.
Land vehicle Vehicle Car Bumper Automotive exterior
 
#380 ·
Here are a bunch of pictures of the BMS install and the start of my belly pan. I'm using 1/8" (3 mm) thick ABS sheet.
Electrical wiring Cable management Electronics Wire Technology
Technology Vehicle


Automotive lighting Product Auto part Technology Electronic device

Thanks to gdirwin for making me aware of wago 222 connectors in this post. They are awesome, and do a much better job of securely connecting wires.

Floor Wood Sport venue T-shirt
Wire Electrical wiring Technology Cable Electronic device

Make a template with cardboard. Cut the plastic with a jig saw set to slow. I still need to enclose the bottom of the engine compartment and the back of the rear wheel wells.

Vehicle Auto part Car City car


Blue sea makes nice terminal covers that works for post lugs. I ordered 4 red and 4 black for the motor and controller connections.

Blue Sea PN# 4012 - red, 2 - 2/0 wire
4013 - black, 2 - 2/0 wire
4014 - red, 3/0 - 4/0 wire
4015 - black, 3/0 - 4/0 wire
 
#382 ·
There were no requirements as far as I know. There was no inspection. The change from gasoline to electric power was self declaring. When I asked about an inspection they simple said, "Don't get pulled over and have a gas engine in there."

It is a good idea to restrain your cells, and to provide some protection for curious fingers.
 
#383 ·
Using a DC speed controller and Arduino, I built a PID controller for my motor blower. I also drive the old oil level gauge with the motor temperature.

Lens Camera lens Technology Room Photography
Auto part Bumper Vehicle Automotive exterior Car


Electronics Circuit component Electronic component Product Technology
Circuit component Electronics Electronic engineering Electronic component Microcontroller


Text Diagram Line Design Technical drawing
Electronics Desk Room Furniture Technology


Wire Electronics Electronic device Technology Cable
Text Blue Line Plot Slope


Looks like the blower ends up being fully on or off, but with a PID controller, it does so very gracefully. I suspect that setting the temperature setpoint at 120 degrees F is a factor. The motor is certainly rated higher, but from the graphs, I see the temperture rise a few degrees at the end when the blower turns off. This tells me that the thermistor in the motor is not directly at the hottest part of the motor.
 
#384 ·
I'm not so pleased with the performance of the blower. The air flow is too low, and the motor temperature climbs to around 210 deg F (100 deg C) at the motor thermistor at speeds above 45 mph sustained for 15-20 minutes. Based on the time lag between pushing current through the motor and seeing temperature rise, I'm guessing there is significant thermal mass between the thermistor and the heating source (brushes), so the commutator region is likely seeing higher temperatures.

I will collect a temperature graph of these conditions, and then go back to the stock cooling configuration (remove the blower band and reinstall the screen band around the motor). I never had the thermistor hooked up before, but the temperature seemed cooler to the touch before I added the blower.

Then I can decide if I need to look for a better blower. I'm considering a jabsco that is rated for 150 cfm (34739-0010 , 6.5 amps). There is a bigger unit rated for 250 cfm, but I don't think I can fit it in the car (35440-0000, 12 amps). The blower I have claims 800 cfm, but based on the 4 amp draw, and being an inline duct fan, there is no way I'm getting that kind of flow through my 2 inch duct with 18 inches of run and two 90 degree turns. I doubt the 800 cfm claim, even with no static pressure. And did I mention the blower sounds just like a shop vac - not a cool sound.
 
#385 ·
After looking at all the specs, I settled on the Jabsco 35770-0092. It's a bit more expensive, buts it's rated for continuous use, so it should be more durable. I've turned it on and it's actually very quiet, so I may just leave it on all the time.

Here it is mounted. I haven't actually driven the car yet, as I have another month or so of work, so I can't share actual performance data... As you mentioned it is quite large...

 
#387 ·
I removed the blower from the car. I was tired of the high motor temperature and the shop vac sound broadcasted from my otherwise quiet electric car. I took some temperature plots with and without the external blower. The temperature is measured using the thermistor that is built into the WarP motor.
Text Green Line Map Plot


The red trace was made with the blower cooling band installed, but the external blower was turned off. Obviously, this greatly reduces the ability of the internal fan to pull air into the motor. I ended this test early because the temperature rise showed no signs of slowing.

The green trace shows the motor temperature with the external blower turned on. The blower really doesn't do much until the temperature is greater than 175 degrees F.

The internal fan measurement was made with the original commutator screen installed and the external blower hardware removed.

Conclusions: The internal fan did about as well as the external blower. The blower is underpowered. It is drawing about 4.5 amps at 12 volts. The 105 c.f.m jabsco draws about the same. The 150 cfm jabsco draws 6.5 amps, and the big 250 cfm unit draws 12 amps.

Noise is a big drawback for air cooling. My inline duct blower sounds like a shop vac. The main advantage of the external blower is the ability to cool the motor while the motor is not spinning.

A blower needs to move a lot of air, and ideally do so without a lot of noise.
 
#389 ·
Thank you for the data.

A local EVer just pointed the squirrel cage fan at his brushes, but did not use the band. He said it worked well and he quit overheating on hills.

Something I'm doing on my 911 is trying to mimic the ICE's air flow. Luckily my motor sits in a channel made by the sides of the battery boxes. With just a little coroplast work I can have air pull in from the top, go through the motor, and get pushed out the bottom, just like the ICE did. If I need to augment the air flow I can put some fans in the engine lid air opening. This has the benefit of also cooling my controller.

I removed the blower from the car. I was tired of the high motor temperature and the shop vac sound broadcasted from my otherwise quiet electric car. I took some temperature plots with and without the external blower. The temperature is measured using the thermistor that is built into the WarP motor.
View attachment 27249

The red trace was made with the blower cooling band installed, but the external blower was turned off. Obviously, this greatly reduces the ability of the internal fan to pull air into the motor. I ended this test early because the temperature rise showed no signs of slowing.

The green trace shows the motor temperature with the external blower turned on. The blower really doesn't do much until the temperature is greater than 175 degrees F.

The internal fan measurement was made with the original commutator screen installed and the external blower hardware removed.

Conclusions: The internal fan did about as well as the external blower. The blower is underpowered. It is drawing about 4.5 amps at 12 volts. The 105 c.f.m jabsco draws about the same. The 150 cfm jabsco draws 6.5 amps, and the big 250 cfm unit draws 12 amps.

Noise is a big drawback for air cooling. My inline duct blower sounds like a shop vac. The main advantage of the external blower is the ability to cool the motor while the motor is not spinning.

A blower needs to move a lot of air, and ideally do so without a lot of noise.
 
#391 ·
It's been a while since my last post. I've 8500 electric miles on the car, and no issues to report.

I've been taking the car to monthly electric vehicle association meetings, and various events to promote EVs. Almost all of the response is overwhelmingly positive. A few people are pretty upset with what I've done to a semi-classic car. They take it personally that I've messed with the "heart of the machine."

A Porsche enthusiast online magazine, dedicated to first generation water cooled model of the Porsche line, captures this reaction in a recent article (with some interesting phrases):
http://flussigmagazine.com/2/post/2015/04/electric-porsches.html
They include links to my car and a few others that participate in this forum: RWAudio and the ReBirth 911.
 
#392 ·
It's been a while since my last post. I've 8500 electric miles on the car, and no issues to report.

I've been taking the car to monthly electric vehicle association meetings, and various events to promote EVs. Almost all of the response is overwhelmingly positive. A few people are pretty upset with what I've done to a semi-classic car. They take it personally that I've messed with the "heart of the machine."
A Porsche enthusiast online magazine, dedicated to first generation water cooled model of the Porsche line, captures this reaction in a recent article (with some interesting phrases):
http://flussigmagazine.com/2/post/2015/04/electric-porsches.html
They include links to my car and a few others that participate in this forum: RWAudio and the ReBirth 911.
Sounds like a German website. Flussig means liquid.
The guy bagging your car admits to having a low IQ then demands everybody listens to his wise admonitions which are actually random gibberish from a clearly strained and undeveloped social conscience.
I only dream of doing as many miles in an EV as you have Joey, well done
 
#393 · (Edited)
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