The end of November I went for my first drive around the block and up and down the street a few times. The first problem I had was the DC-DC controller fuse blew, draining my 12 volt battery, shutting down the controller leaving the car dead in front of the house with all the neighbors watching. Shutting everything down allowed the battery to recover enough to get back in to the garage. Looking on line I found this was a common problem and is either caused by the capacitors in the DC-DC converter trying to drive the car when the main pack sags or by an AC ripple on the DC high voltage caused by the controller. I installed a diode to prevent the capacitors from back feeding and a 100 uH inductor to kill any ripple. I also changed from a 10 amp fuse to a 15 amp fuse. With about 50 miles on the car since I have not had any more problems.
The next problem I ran into was not having enough heat. At 20 degrees the amount of heat was enough to keep the windows from fogging and make it tolerable to drive. The problem was there was not enough heat to melt frost off the outside of the windows. This is kind of important in the winter in Iowa. So I decided to re-do the heater. I decided to use a couple 1500 watt PTC heater elements that I removed from heater I found at Home Depot for $20 a piece.
The problem is getting to the heater core. The entire dash has to come out of the car along with the structural cross bar. Working in the unheated garage, with one of the heater running inside the car, it took me a day and a half just to get to the heater core. The heater core slides down into the black square in the center of the photo below.
Once I got the heater core out it was time to modify it to hold the PTC elements. Taking a grinder and pliers to the heater core made room. I stacked the two elements and held them in place with some fire block expanding foam. Then sealed up the rest of the fins and small holes with some high temp RTV. The final heater core ready to be re-installed is below, with the scraps of aluminum that were removed from the heater core in the back ground.
I have the heater core back in and wired but I had to order a new switch that will be installed in the dash to control the heaters. I will have a low and high settings for 1500 and 3000 watts. So the dash panel will stay out until I get the new switch.
After hearing more about bad things that can happen to Li-Po4 cells when they are charger below freezing, I decided to add some battery box heaters. I found some flexible silicone rubber heaters on line at Omega.
I have these hooked up to 120 volt AC plug to connect when I pull in the garage Even at 2 watts per square inch I found they get very hot. To disperse the heat I attached these to a piece of 0.063 aluminum under each battery pack between the insulation and the battery and connected them through a cycling relay that turns them on for a minute and off for a minute. From 20 degrees they get the batteries up to about 45 degrees in about 3 hours.
I also did a little body work on the car. Like most ICE cars, there was a cutout in the back for that tail pipe. Since I don't have a tail pipe it looked silly to have a cutout. I used some fiberglass cloth and resin to fill the hole and covered the panel with some foe carbon fiber. I think it make it look much better and I'm sure will cut 2 seconds off my 0 to 60 time.
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