The making of an all electric EV VW Cabriolet

This blog follows my process of converting a 1992 VW Cabriolet to an electric vehicle. As an EV it is quiet, dependable and has plenty of pep and range to get around town.

Tuesday, September 08, 2009

All the better to see you with

And now to start catching up for the last two and a half years - somewhat chronologically:

To watch the batteries a little better I added a red LED digital volt meter. It's bright enough to read except in bright direct sunlight, and matches pretty well with my handheld meter. I'll get a much better read on the batteries now, and can watch them in real time. The meter updates a few times a second.

The good is that its:

-cheap
-bright
-isolated power and sense pins

The bad is that it's cheap. I burnt two of them before I figured out that it can't really handle the high voltage leakage paths from the pack to ground. When I hit the accelerator, the meter goes crazy, and in a few days dies with one part burnt off the PCB. After looking at the toasted parts I figured it must be arcing from high voltage to the house ground, and probably due to the noisy voltage spikes when the controller is actively chopping the DC. A $5 isolated 12V-12V DC-DC supply on the 12V power input has fixed it, and it's still running strong two years later.