'86 Electrical Drain

[Loren Lundberg (912)]

Parked car under normal conditions Sunday. Monday AM - stone cold dead. Found batteryshort on water (AZ summer), refilled & put on charger for 4 hours. Did NOT disconnect the cables. Tried again - still dead. Decided on a dead short as the culprit, disassembled car, removed 11 month-old battery and bought a new one. Before reassembling car, tried and car started.
Tues AM - stone cold dead; removed both cables, put short 3/8" bolt into the cable receptacles and installed the charger. After two hours it's up to 6 volts and climbing.
So where do start in the AM - circuit tester at the fuse block? Or? Any suggestions are welcome.

[Jim Trekell (22375)]

Re: '86 Electrical Drain

Something like this to happen would make me check the alternator to see if it is draining the battery or even the horns. If your horns do not honk with the charged battery, the electrical current could still be sent with a malfunctioning horn contact on the steering wheel. I am not real good on electricals, just something to remove from the list of possibles. With all the relays in your 86 one of them could be stuck on/shut discharging the battery. Good thing it is easy to just remove the battery ground connection if you don't find it right way.

[William Clupper (618)]

Re: '86 Electrical Drain

Loren, I'd suggest the purchase/rental of a good external amp gauge the style that clamps around the battery wire. To drain overnight, you need a drain of several amps. If you '86 is like my '89, I'd start with making sure the interior lamp timeout feature is timing out. If that checks out ok, the amp meter should show a few amps drain, and the fuseblock would be my next stop pulling until the drain drops to a few Millamps, the computer and radio clocks generally run under 100MA in all, usually well under. I suspect you are looking for a drain of a few amps.

[Joe Lucia (12484)]

Re: '86 Electrical Drain

Loren and Bill-----

I absolutely agree. To "flatten" a new, fully charged battery to the level you describe would require a substantial current draw. In fact, something somewhere might be getting quite hot. That could pose other problems.

[Tommy Flick (47713)]

Re: '86 Electrical Drain

I'd vote for the alternator short...My wife's '85 did the same thing.

[Jack Humphrey (17100)]

Re: '86 Electrical Drain

Like others, I'd first suspect the alternator and a shorted diode (or two) in the alt's internal 3-phase rectifier circuit can well handle the current necessary to discharge a battery without leaving telltale symptoms (hot wires, Etc.). It's pretty easy to troubleshoot, just disconnect the alternator, charge the battery and let 'er sit to see if your discharge troubles go away.

On electrical problems like this, you can try this/that or put science to work... A competent auto electric shop should be able to diagnose the cause(s) of discharge in 30-60 minutes (finding & fixing is another issue). Shop labor rates are typically $40-80/hour and that's pretty cheap considering your personal time to look here/there, try this/that...

[Loren Lundberg (912)]

It was the alternator and, would you believe it,

the warranty had expired!! 21 years ain't bad....