Have you ever wanted to own an electric car? or have you ever wanted to drive a Porsche 911? I wanted both, so I decided to build one. This blog is here to document my journey as I convert a 2002 Porsche 911/996 Carrera 2 from a gas guzzler to a completely electric vehicle - not a hybrid!

Sunday, November 4, 2012

100MPH, no problem!

For the last week I have been driving the car daily and spending extra time balancing the batteries more and more with every charge. I think I have about 50% range improvement so far.

Today, I did a few things that have been hanging over my head.  First I removed the Soliton1 Hall Effect pedal sensor and put back in the original Porsche Throttle Position Sensor.  The purpose for this was to improve the ECU communication with the TCU to include the TPS sensor position so it can assist with when to shift, like when I am backing off the pedal it may shift to a higher gear or downshift if I kick-down quickly.

The second thing I did was update a few of the parameters of the Soliton1 to improve the sportiness of the car now that I am more comfortable that things are working properly.  First I had to recalibrate the throttle pedal because of the change back to the Porsche TPS.  I then increased the slew rate from 100 to 300Amps/Second.  I also temporarily removed the low voltage limits so I could do some testing with a full pack to see how low the pack dropped under various loads.  I decreased the TPS deadband to 3% so when I hit the pedal it doesn't have to move far to make a difference.  I also change the 50% power to kick in at the 50% TPS position.

With these changes, I was eager to drive.  I charged up the pack and headed out.  In reverse, a slight tap on the pedal made the car move immediately and quickly.  Shifting back into drive and hitting the pedal, the car jumped!  I sped around the block and the car performed great!  Previously, it was a dog off the line and I was afraid others would honk at me for going too slow from a stop.  Now the car jumps off the line fast and moves through the gears like you'd expect a high performance street car!  During hard acceleration, the pack was putting out 600+ Amps and dropping from 240V to 155V.  I have some temp sensors on the battery terminals, and the terminals got up to 70C for a few seconds.

I took the car on the freeway and raced it up to 100MPH, no problem in 4th gear, and crushed my previous top speed of 80MPH!  So cool.  There was more speed to be had, however, if you get caught going above 100MPH here, you lose your license for 1 year, so I need to save the top speed tests for the race track.

For my next test, I wanted to check the 0-60MPH time.  I setup a timer and gunned it.  The tires barked a few times as the spun trying to get traction!  I didn't expect them to spin, but cool!  Anyways, the car raced up to 50MPH quickly in 2nd gear, but jerkily shifted into 3rd and this caused me some concern, and the slow shift transition screwed my time.  The 0-60MPH test was over.  I'm still suffering from low ATF fluid, so the shifts are sometimes delayed and jumpy.  I will have to wait to record a time until I have more ATF fluid in the car.


  1. Nice looking car! If you balance the batteries before installing them the balancing goes much faster and easier. Hopefully they will be balanced soon.

    What did you go with for your low voltage settings in the Soliton?

    Also, with a DC motor you get more torque at lower RPMs so if you are cruising along and want to accelerate quickly you do not want the transmission shifting down. Depending on the motor RPM at the time you will want it to shift up to get a better acceleration. Backwards from an ICE.

    David D. Nelson

  2. Congratulations on getting the car up to 100 mph, that is quite a mile-stone. I suspect you are suffering from the same problem I am having with my '52 Chevrolet truck-no cabin heat. I have been driving the truck around to get some bugs out but the cool temperatures together with no side windows is proving a bit chilly.

    Have you considered putting in some type of heat pump or will this car be for summer use only?

    Jim Holbrook

  3. Possibly you could adapt the water cooling of the speed controller to heat the cabin? If it gets hot enough, or you could install a 12v heater and a 12v aux battery

  4. Hey Kurt,

    Your project looks great! Just a tad bit sexier than my 1996 Electric Geo Metro conversion. I've only gotten mine up to 73 mph, but that was in a 55 zone, and I knew where the cop parked.

    Probably my wierdest experience was getting pulled over for a speeding ticket, and I said "but Officer, I don't even have an engine in this car!" and he said "Yeah, yeah, I've heard that one before..."

  5. enjoy reading about builds like this. Yours seems to have come together faster than most.

    Enjoy your drive!