Parasitic Battery Drain!

[86VickyLX]

Where is the relay on an 87 GM?

The rear defroster relay is part of the switch. It is a timed relay and will shut off in approximately 10 minutes from when it was turned on. You can tell if whether or not it's on by the little yellow/orange light on the bottom. Another way you can tell to see if your defroster is always on is by taking a volt meter, going to the rear windshield inside the car, and probing the windshield at the two ends of the grid. One side should be 12v, the other side 0v. If you have 12 volts then the defroster is engergized and will kill your battery quite quickly.

In an off topic but completely pertinent story. I recently put a 3g alternator in a 1991 F150. The owner's complaints was battery kept going dead after even a day or two of driving. Turned out, the alternator was overcharging and the battery just couldn't handle it. When I replaced the old 2G which was replaced once before I saw that the rectifier plug was badly melted and the wires were exposed. It's been about 2 weeks since I put in the alternator. No more complaints. No more stranded on the side of the road.

[L1011tristar17]

If the plug is melted and parts of the wires are exposed, could that be causing the drain? (even indirectly?) I'll go check tomorrow but last I remember the alternator plug on my car looked really old and worn out.

[86VickyLX]

yes. Also feel the alternator after the car has cooled down. If its hot the alternator has a short in it.

[BerniniCaCO3]

what some people are saying above, is that charging isn't (necessarily) the issue: an alternator could put out 13.5-14.5 V, but still have other issues. Voltage at idle is not the whole story for testing alternators.
I've also seen them have intermittent regulator problems. Fine one minute, dead the next, the fine again: customer had a battery light on the dash that would come on, go off, come on.
But we're still guessing in the dark here.
Have you tested the amperage draw yourself with a regular 10amp ammeter? What are you reading?

[L1011tristar17]

Battery puts out 20 milliamps when the car is off (computers off, no hood light, etc.) which seems alright to me. I tested it three different times so I think whatever is causing the drain is intermittent (relay, maybe?) On a side note, the electrical connector to the alternator is absolutely toast. It smells burnt and some of the wires look about ready to fall right out. I'm getting a new one today so that may solve some of the drain problem. At least it will be a nice thing to have fixed.

[sly]

if the alternator has the two clip on connectors... it's a 2G (second generation). Replace that fire hazard with a 3G. There's numerous threads about that swap.

[L1011tristar17]

I plan on doing the 3G swap sometime this summer when I don't need to use my car as frequently. The current alternator is "new" (read: rebuilt) but is still pretty weak. If I plan on upgrading my sound system, I need something better. Plus this "new" alternator makes this awful chirping sound at start-up. I got a new connector in, so that's one less thing to worry about. The connector literally fell apart as I removed it from the alternator.

[L1011tristar17]

Here's what the old alternator connector looked like. I guess I can say I dodged a bullet by replacing it.

[gadget73]

yeah thats what they look like just before they catch fire. I'd also suggest peeling back the split loom on the harness between the alternator and fender and checking that mess out. Sometimes that will also melt down and cause problems.

[86VickyLX]

Replace that alternator pronto! Ditch that fire hazard and get a 3g. The swap doesn't require much work.

[L1011tristar17]

I'll look into replacing it once I start working again over break but for now the current alternator is doing its job and the bad connector was replaced. My family isn't really into cars, so what I see as a necessary upgrade they see as another $30 down the drain. My parents were horrified when I told them that I would need the 3G alternator from a junkyard (instead of a "new" one). "Why replace the alternator when the one you have works just fine?" I'll just have to wait until its my money paying for the upgrade and I have the time and tools to do it.

[L1011tristar17]

How straightforward is the swap? I've seen a lot of threads started by people who got confused somewhere during the process.

[sly]

if you pay attention to the wires... it's really easy. The only difficult part is grinding out the bracket to make clearance for the lower part of the 3G housing... and if you have a hand held grinder... it's not really a difficult thing.

[L1011tristar17]

I don't have any grinding tools. Wouldn't it be easier to swap out the original bracket for a 3G one as well? The current one is actually cracked (and poorly welded back together) so I'd be replacing that anyways.

[L1011tristar17]

I've come to a realization that the battery may not be draining after all. It's possible that the shop actually fixed that but the alternator isn't charging like it should. The last few times I've checked the drain, it's been a constant 20 milliamps. I'm saying this because after heavy driving, I got my battery tested and it only had 60% charge, and it doesn't drain overnight like it used to. Either way, I'm still gonna keep a close eye on things.