Thursday, August 23, 2007

12V Auxilliary Battery Dies!

While cruising over to my girlfriend's house this evening, the whole system just shut down on the road. That was a rather scary experience. The hazard signals started flickering and nothing would turn on. After pulling over and checking the voltage on everything, the pack was nicely up at 150V but the accessory battery was down to 10.5 volts. With the key on, the DC-DC converter light was on; however, when I checked the DC-DC fuse, it was blown. Apparently, I've been running down my accessory battery for awhile now.

The car is stranded for the moment until I try replacing the fuse to see what the issue is. Worst case, I can charge the accessory battery with a long extension cord just to get the car home.

Ugh, goodnight.


Ross Cunniff said...

Wow, that sucks. I wonder if there is any way to connect the DC-DC converter output to an indicator light on the dash (like, hmm, the generator light!). I'd have to think about this more, though - to keep the 12V battery from lighting the bulb, you'd want to isolate it via a relay (hmm - or maybe a diode?)

TimK said...

Actually, I could have seen this coming since the 12V console voltmeter kept creeping down. Actually the red light at the bottom of the fuel gauge is much closer to the accessory battery in the front compartment. Perhaps a comparator circuit that shows when the voltage dips below a 11.8V threshold (it should be 12.6-13.6 with the DC-DC) would work to drive the lamp.

What really confused me is that the red LED on the DC-DC converter was still on, giving me the impression that it was working, even though it wasn't.