charging system issues: the return of

[davidpertuz at mindspring.com]

Shit. I seem to have charging-system issues again, with very bad timing due in part to my procrastination. So I'm soliciting some possibly enlightened commentary. Car is a P10t.

-Last drove car on 7/5. Went out a week later to drive it and found battery dead. Found left rear door was not closed completely, so dead battery presumably caused by dome light current drain. No urgent need to use it, so I decided to jump it later. I have a battery charger, but the battery had too little charge for it to work - multimeter showed no more than ca. 2V across the battery terminals.

-Got a jump-start from my girlfriend last night, drove around for half an hour to recharge battery. Noticed alternator whine (also heard as variable noise in radio static when on a non-channel freq.) but didn't think much of it. Parked in garage again, tried to restart, car is stone dead, still. Absolutely nothing. Multimeter shows ca. 1V across battery. WTF? Battery was new some time last year, don't remember exactly when. 

This first, and most obviously, suggests that the battery is, for some reason, bad, and won't take or hold a charge. But I'm not entirely convinced that this is the case. I could borrow my Fiat's battery and hook that up to test, but that one's dead too (I didn't put it on a trickle charger over winter, oops) and I'm really short on time. So I'm going to get another jump tonight and proceed with some diagnosis. I am not entirely convinced it is simply a bad battery because: 1) the battery is quite new; 2) recent (last year) history of charging system issues; and 3)hunch

Background of recent issues:
-For a year or two until spring 2008, the car had poor voltage regulation - voltage was often unusually high, never low. I suspected, and later confirmed, that this was caused by a broken connector on the alternator harness, where it plugs into the voltage regulator. put new harness on, problem solved. Replaced one suspected-bad alternator (warranty) before I figured this out. Problem solved.

-Last year, I started having current-drain issues, where the car would go from a full charge to stone dead overnight. After confirming the battery was good, I looked for a current drain and found one on the circuit that contains the radio and dome light. Dealt with this by pulling the fuse whenever I shut off the car to prevent a dead battery, until I could trace the fault in the circuit, which I never got around to doing. Eventually, this current drain mysteriously disappeared, and I no longer had to pull the fuse. Dunno why.

My question: is there anything other than a bad battery (that is not taking or holding a charge) cause my new problem? The fact that, after driving for 30 minutes, the battery was just as absolutely stone dead as it was beforehand - not 10V or so, but only 1V-2V - makes me suspicious. I haven't thought of what other options might be. Y'all's input is welcomed.

thanks,
David
Chicago