Thursday, September 16, 2010

Throttle Detail

I had to take the throttle out of the car because the rear motors were trying to go even at zero throttle. This is a function of the kind of potentiometers I am using. They are supposed to be 0 - 5k ohm, but actually they are ~750 ohm - 5.2k ohms. The Alltrax controllers I am using for the rear motors don't have the ability to set the dead zone on either the top or bottom of the sensor range, probably because they expect the controller to be switched off at zero throttle. However, I am using the built in monitoring functions of the controller (a big plus for the Alltrax controllers) to get the motor current, battery current, battery voltage, and controller temperature. If the controller is off at zero throttle, that information isn't available.

Anyway, I solved this issue by putting in microswitches connected to 22 ohm resistors. When the accelerator pedal is not depressed, the microswitches are activated and the 22 ohm resistor is put in parallel with the output of the potentiometer. This lowers the resistance seen by the controller to ~23 ohms, which the controller reads as zero throttle. Problem solved! Anyway, here is some video...

Tuesday, September 14, 2010

...And the test drive

I didn't get up to 65 MPH like I wanted but I did get to 62.  I'm happy with how much quieter it is compared to last September and this should make my commute all electric.


Ok, here are some videos of the stuff I have spent the last 18 months working on.

Video 1:

This is how I have laid out the old engine compartment.  Since I took out everything including the transmission, it made sense to me to put all the batteries up there; it replaces the weight of the engine keeping the car's balance and handling and it is a big hole with nothing in it.  I was trying to keep all the usable space usable and have the car look the same as when I started.  I wasn't able to get all four batteries installed there but I'm sure it would be possible if I were clever enough.

Video #2:

This is one of the front wheel hub motor installations.  In order to install the 6KW BLDC hub motors, I had to have the front struts modified.  Obviously, the car started out as rear wheel drive only so the front struts only had a shaft onto which bearings, brakes, and wheel rim were mounted.  I had to turn this around and provide a tube into which I could slide the shaft of the hub motor.  These turned out really well and I'd like to thank the guys at Hardcore Customs for a job well done.

Video #3:

I'm avoiding talking about the snowmobile clutch failure because I'm so bummed it didn't work.  But this video shows what I did to drive the rear wheels.  Basically, each wheel is driven by a D&D ES-33 motor controlled by an Alltrax AXE 7234 series motor controller via a 4:1 chain drive.  This is the same setup that I had last September that didn't have enough torque to climb up my driveway.  The 4:1 reduction is basically the equivalent of 4th gear in the old transmission and even the old ICE wouldn't have gotten up the driveway in 4th gear.  But, by adding the two 6KW motors to the front wheels, the car now goes right up the driveway!  Referring back to my post from last September, I laid out my options for how to address the driveway shortcoming and I'm proud to say that I accomplished my first option.

Video #4:

Obviously, there are still lots of things in a rough prototype state.  One of the things that is first on my list is to permanently mount the rear controllers.  This mount actually goes right above the motors, freeing up most of the trunk space.  Now, all I have to do is figure out what to do with that BIG hole where the gas tank used to be....  :-)

I think that is a good first cut overview of my progress.  Now, I'm going to go out for a test drive wearing my big EV grin and bring back some video.

Sunday, September 12, 2010

It Lives!!! For Real This Time

After nearly 18 months of working on my dream beemer, tonight was the first test drive that I really felt was successful.  I drove the car nearly 10 miles at speeds of up to 65 mph and at the end, I climbed my driveway, which was my down fall last September, without a hitch!  I am so excited.

I know I haven't been very good about updating my blog here but I've been spending every spare minute since I got the car back from Hardcore Customs out in the garage working on it.  I ran into plenty of snags, one of which ended up throwing out my snowmobile CVT idea (more on that later).  I'll spend the next couple of weeks doing cleanup and documenting everything I did including more pictures and video.  But for now, I just wanted to shout:  I DID IT!!!!