Alternator assassin?
09-08-2012, 11:36 AM
#1
2nd Gear Member
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Join Date: May 2008
Location: Florida
Posts: 478
Alternator assassin?
The other day I pulled out the driver's seat to clean out and oil the recline mechanism that was sticking. Friday, I got in the car to discover a dead battery. When I opened the hood, the caps of the battery were popped off, and there was battery acid splashed all over the engine bay, staining the painted surfaces.
Last night I switched out the battery that was still under warranty, and took it for a test drive. It was getting just above 8 volts on the dash gauge, there was a ALT warning light, and the headlights or gauge didn't seem to register a blip in the throttle, which to me means the alternator isn't doing its job.
Today I went out to check it, and the battery is dead, completely. Fortunately, the battery didn't spray acid all over the place.
Under the front seat is a small amp, which seems to be hooked up correctly (although I don't know jack about car audio), and the seat also has a power lumbar, which is also hooked up correctly.
What did I screw up?
It's an '89 GT hatchback.
Last night I switched out the battery that was still under warranty, and took it for a test drive. It was getting just above 8 volts on the dash gauge, there was a ALT warning light, and the headlights or gauge didn't seem to register a blip in the throttle, which to me means the alternator isn't doing its job.
Today I went out to check it, and the battery is dead, completely. Fortunately, the battery didn't spray acid all over the place.
Under the front seat is a small amp, which seems to be hooked up correctly (although I don't know jack about car audio), and the seat also has a power lumbar, which is also hooked up correctly.
What did I screw up?
It's an '89 GT hatchback.
09-08-2012, 11:39 AM
#2
6th Gear Member
Join Date: Nov 2006
Location: Spfld, MA
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Likely coincidental. Sounds like an overcharge followed by an undercharge. Initial signs of voltage regulator failure.
Give the acid a good bath with a hose, don't want it sitting on metal for too long, chemical reactions will lead to rot.
Give the acid a good bath with a hose, don't want it sitting on metal for too long, chemical reactions will lead to rot.
Last edited by mattdel; 09-08-2012 at 11:44 AM.
09-08-2012, 11:59 AM
#3
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But two separate batteries?
After I put the seat back in on thursday night, I didn't drive it or anything. It sat overnight and spewed acid all over the engine compartment. Dead in the morning.
Last night, the new battery was at a decent charge before the test drive. I drove it around the block and parked it, and the battery is completely dead today? I mean, not even enough for the underhood light or to power the dash.
I could understand if the regulator died and it was over or under charging while it was driving, but in 2 days it has driven around the block, once.
After I put the seat back in on thursday night, I didn't drive it or anything. It sat overnight and spewed acid all over the engine compartment. Dead in the morning.
Last night, the new battery was at a decent charge before the test drive. I drove it around the block and parked it, and the battery is completely dead today? I mean, not even enough for the underhood light or to power the dash.
I could understand if the regulator died and it was over or under charging while it was driving, but in 2 days it has driven around the block, once.
09-09-2012, 05:28 PM
#6
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Ok, I could buy into that, but would a failed regulator overcharge a battery and make it explode when the car was parked overnight? And would it discharge a new battery overnight? Both without the car running at all?
09-09-2012, 08:12 PM
#7
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I'm starting to doubt my original theory after re-reading all this, but the simple fact is that electrical problems are tricky to pinpoint in words. I'd start with checking your main cables for problems, then check for a draw over 35mA while off, and have the alternator checked out on a test table, not with a DVOM. I'm not entirely convinced you caused the problem, more like exacerbated it.
09-09-2012, 08:37 PM
#8
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Join Date: Feb 2010
Location: Connecticut
Posts: 2,549
First and foremost I would neutralize the battery acid that sprayed all over. You need to this right away. You said there is a amp under the seat. Is this amp connected to power with a fuse? Power lumbar is factory so that will be fused. It will blow the fuse if shorted. If someone installed the amp without putting a inline fuse and it shorted, I could see where it could blow the battery.
09-09-2012, 10:34 PM
#9
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The amp is fused with an inline right before the battery. I guess its time to pull the alternator and take it to discount to see if it goes. And while I'm at it I can pull the fuse from the amp power line and see if the battery still discharges.
All the fuses look good. Maybe something grounded out and is causing a drain... Either way, the alternator doesnt seem to be charging when the car is running. Usually I can tell by the headlights intensifying when you throttle it. And the derp light in the dash. LOL
Seems like two unrelated problems that I didnt have before I messed with the seat...
All the fuses look good. Maybe something grounded out and is causing a drain... Either way, the alternator doesnt seem to be charging when the car is running. Usually I can tell by the headlights intensifying when you throttle it. And the derp light in the dash. LOL
Seems like two unrelated problems that I didnt have before I messed with the seat...
09-16-2012, 01:44 PM
#10
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Update on this for anyone interested. Mechanic tested the draw on the battery with the car off, and it was huge. Turned out that the alternator shorted out inside. He said it probably massively overcharged the battery and popped it while I was driving the day before the mess started. So I guess it started with the regulator, and somehow it fried the alternator, which then drained the second battery, and was entirely unrelated to the seat. LOL
So props to mattdel for a perfect call.
So props to mattdel for a perfect call.
