Alternator or bad battery?

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Jan 16, 2021
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I have a 2000 silverado 1500 that I have had for quite some time that I used to daily drive but the past couple years I rarely drive it due to getting a new truck. Decided to keep the old one for a backup/beater rig but I swear the thing goes through batteries like crazy. I have an interstate battery in it that is about 4 years old and dead as can be. I jumped it this evening and let it run for about 20 minutes and tried to start it and dead again. The volt meter shows it’s charging where it always has since I have owned the truck. No battery light or anything to that nature. Could it be the alternator not putting out the correct amount to charge the battery or is the batteries just getting ruined from setting around and rarely being driven?
 

Ohio91

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What is the voltage reading at the battery posts when the truck is running?
Unfortunately didn’t get that far that was my next step but someone in the family needed my volt meter worse then me apparently.
 

Tomioka

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Check for parasitic draw with a digital multimeter between the negative battery terminal and negative battery cable.

What I've noticed on these trucks is that the ABS module draws too much current when a parasitic draw test is done.
 

Ohio91

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Check for parasitic draw with a digital multimeter between the negative battery terminal and negative battery cable.

What I've noticed on these trucks is that the ABS module draws too much current when a parasitic draw test is done.
My sister had a 02 that they rarely drove and to keep from jumping it they unhooked a battery terminal. Could be onto something. If that’s the case I’ll throw a solar trickle charger on it.
 

Tomioka

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My sister had a 02 that they rarely drove and to keep from jumping it they unhooked a battery terminal. Could be onto something. If that’s the case I’ll throw a solar trickle charger on it.

If you want to get experimental, pull the ABS fuse after a full charge and check after X amount of time.
 

Ohio91

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If you want to get experimental, pull the ABS fuse after a full charge and check after X amount of time.
I believe it is some kind of draw on it. When I drove it every day never had an issue. Now it may set for a couple weeks before it’s started and it’s a no go.
 
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Two problems I discovered on my late father's 1992 Silverado that might be relevant:

1. The "heavy-duty" relay for the emergency flashers (separate from the one for the turn signals) liked to overheat, break the plastic covering, and short against metal under the dash, draining the battery. The truck is on its third relay since I inherited it 10 years ago.

2. The driver's-side plunger switch for the interior light failed so that the light stayed on, guess what, draining the battery. I removed the switch and simply did not replace it. Planning to junk the truck soon anyway.

Here's a bonus No. 3. Had to replace the headlight switch twice. It didn't short, but maybe others have had that happen. Which would, you guessed it, drain the battery...

I ended up installing a disconnect switch on the battery just in case.
 
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The battery is dead from sitting around and not being charged up. If it wont start after jump starting the battery probably is no good. You should get a a battery maintainer for a vehicle that doesn't get much use.
 
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https://www.batterytender.com/junior

battery_tender_jr.jpg
 

JHZR2

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My 98 S-10 has a hard to find parasitic load. Sounds similar to this. Let it sit too long and the battery will be low.
 
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