Monday, August 7, 2017
Greetings, Avian Motors Enthusiasts (and random people I subject to my emails),
I took a long drive in the Ghost this weekend. Still working out the bugs before I put the body on. I got two error codes from the motor controller during the trip and had to turn the vehicle off and on to start it back up. What is this, Microsoft? At one point I thought I smelled some electrical. Plus the battery voltage seemed to drop more than expected at high currents under acceleration.
I got it back home and worked through the debug process. The codes had to do with over voltage and the main relay welding. At first it seemed I thought the batteries might be getting old and the series resistance/impedance might be the problem. Then it looked like the main disconnect. But the master relay was hot, very hot. This wasn't right. I took it apart and there was a small nut in the contacts. This failure matches all the symptoms!
I cleaned up the master relay and put everything back together. That was yesterday, Sunday. So I will have to wait until next weekend will conduct more tests. I am optimistic that I am getting down to the smaller problems now. Hopefully I will have things up to par within a few weeks and can put the body on.
I think what happened is that I dropped the nut while bolting in the main contactor. This is in a box in a very tight place with little room to move your fingers. I suspect I thought the nut dropped on the floor and I just grabbed another nut as a replacement. After rattling around inside the main relay box, it eventually got lodged in the relay. This is a big relay that can handle 500amps.I also changed the way the box mounts to make it easier to get at.