My truck, the battery serial killer...

[FRANKENTRUCK]

For quite some time now I have been having an ongoing mysterious electrical problem with my 81 SWB Stepside that turned into a multi-year odyssey. When I got this truck back from being painted several years ago the battery was completely dead. I ended up buying a new battery which seemed to fix the problem. But I noticed over a period of about 2 weeks the battery kept getting weaker and weaker. If I did not crank the truck for three days, the battery would end up dead from just sitting there.
I would jump start the truck and drive around to charge the battery, but the battery would eventually die regardless. This happened about four times and the truck ate that same number of batteries because I kept having to buy new ones. Every single mechanic that I took the truck to could not find a single thing wrong with it. One of them did notice that the painter did not reattach the grounding straps, so he installed some in there for me. But it did not fix any part the problem.
So I took the truck to a mechanic that was recommended to me, and he discovered that the alternator that was in the truck did not have a volt regulator in it, which was putting out way too much voltage. So he installed an alternator that did in fact have a volt regulator. The truck seemed to run fine for a few days but then I noticed that the battery was getting weak again. So the truck was continuing to drain the battery while simply sitting in the yard like it had done before, but this time the battery was NOT fried like the others, and would take a recharge.
This new mechanic then tried something different. He would remove a fuse from the truck's fuse box and see if the battery would remain charged or not over a period of days while sitting idle. If not, he would replace the fuse and remove another. He continued to do this over a period of weeks until eventually he FINALLY figured out what the problem was. For some reason the volt gauge was draining the battery while the truck was turned off.
So I bought a couple of New Old Stock volt gauges at a Chevrolet dealership, and he installed one of them in the gauge cluster. He put the recharged battery in the truck with the NOS gauge, and after two weeks discovered that the truck finally did not drain the battery.
So I had two problems at the same time that I did not realize when the truck kept murdering batteries. The alternator that did not have the regulator in it was putting out far too much voltage. This was frying my batteries and making them useless. And whenever the truck was sitting, the volt gauge was draining the battery the rest of the way. So when the newest mechanic replaced the alternator with the correct one, the battery frying issue was stopped but the battery draining issue still existed.
I wanted to put this out there for others to learn from because it went through four mechanics to figure out that it was the volt gauge AND the incorrect alternator that was apparently causing this problem. Both of those problems were contributing to the battery dying but it was very difficult to figure out that it was TWO things instead of one. Check those voltage gauges guys! This is something that usually is not considered when dealing with electrical gremlins.

 

[gmbellew]

you can check for voltage across the fuses with key off to check for parasitic draw. should be 0.0volts on most fuses, unless there is a (keep alive thing like the radio or a clock) on the circuit.

 

[FRANKENTRUCK]

you can check for voltage across the fuses with key off to check for parasitic draw. should be 0.0volts on most fuses, unless there is a (keep alive thing like the radio or a clock) on the circuit.

All of the mechanics did EXACTLY that, but for some unknown reason no such parasitic draw was detected by any of them. I still have not figured that one out.

 

[fast 99]

There are 4 primary causes of a low battery.

Bad battery, parasitic drain, not/low charging, excess starter draw.

Of course, it is more complicated, but it boils down to that,

Can use a test light across a disconnected battery cable. It shouldn't light. There are other methods, but they require more diagnostic equipment.

 

[scrap--metal]

For some reason the volt gauge was draining the battery while the truck was turned off.

Thanks for the PSA. It's good to keep that in mind.

I've witnessed inexplicable electrical gremlins before, even when preforming the proper checks.

All of the mechanics did EXACTLY that, but for some unknown reason no such parasitic draw was detected by any of them. I still have not figured that one out.

Sometimes it doesn't make sense even after it's fixed.

 

[Jeff Lewis]

clock

 

[FRANKENTRUCK]

I forgot to mention that the old volt gauge was seemingly working fine until JUST before the mechanic installed the NOS volt gauge. It completely stopped working before it was replaced. So it was old, defective, and on its way to the scrap heap.

 

[Octane]

There are 4 primary causes of a low battery.

Bad battery, parasitic drain, not/low charging, excess starter draw.

Of course, it is more complicated, but it boils down to that,

Can use a test light across a disconnected battery cable. It shouldn't light. There are other methods, but they require more diagnostic equipment.

We had a firebird with a starter pulling high amps and it was draining the battery, if I remember correctly, the new starter fixed the issue. And I think the alternator died afterward too