Odd battery problem Sears Platinum Marine 31

[007]

2011 tacoma
I went to start my truck this morning after driving it last night, but the starting battery was too dead. I always maintain my batts with the approved oddysey chargers and nothing was left on. I pressed my "combine" switch and waited, but it was still to dead for anything more than a partial crank followed by clicking.

I pulled out my voltage tester and checked the reserve battery, it was 12.7, the starter battery was 8.8, but combining them through my switch changed nothing. It was -16 Fahrenheit and I wanted this thing going and was able to jump start it with the wife's car instantly after I connected it to the dead starter battery.

I drove the truck to work (10 minutes) and restarted the truck just fine. I looked at my connections and saw that the top + post was loose, and by loose I mean I could spin the post (the part attached to the battery, not the terminal) a 1/4" in both directions. I checked the voltage and it was now 12.8!

I don't understand how it wasn't allowing me to combine both batteries, and I'm not sure how it went from 8.8 volts to 12.8 after such a short drive, but the loose top post must have something to do with it.

 

[dwh]

That top post is supposed to be basically welded to the plates. If you could spin the post, then it's broke loose from the plates and the battery is shot.

The battery was at 12.8 but since the post was loose and not making good contact with the plates, then the POST was only showing 8.8. When you jimmied it around, the post made better contact with the plates, and now the post showed full voltage.

As for combining; it was combining, but since the post wasn't making good contact with the plates, nothing happened.

 

[007]

That top post is supposed to be basically welded to the plates. If you could spin the post, then it's broke loose from the plates and the battery is shot.

The battery was at 12.8 but since the post was loose and not making good contact with the plates, then the POST was only showing 8.8. When you jimmied it around, the post made better contact with the plates, and now the post showed full voltage.

As for combining; it was combining, but since the post wasn't making good contact with the plates, nothing happened.

That makes sense, thank you!

The saga continues, swapped batteries, truck starts runs, does a few short trips then I turn it off but leave it on acc for five minutes, go to start it and it clicks.

Somehow there is a violent power draw happening, I jump it, put a volt meter on it and it shows 14.4. I let it charge for a while and shut it off. I pull the negative and clamp my volt meter to the post and and the negative grounds show 10.0 volts, anthe leadsere I touch shows 10.0 even after I pull off the winch, compressor, etc. I'm starting to think the starter or alternator is shorting?

 

[dwh]

Probably not the alternator. You wouldn't get 14v when running.

Possibly starter solenoid.

 

[007]

Probably not the alternator. You wouldn't get 14v when running.

Possibly starter solenoid.

What if the diode is bad? Probably wouldn't cause a major draw would it? I'll disconnect the starter and see if that clears it up. Thanks again!

 

[007]

Disconnected starter and alternator, it still has a 1 amp, 10 volt draw coming from the main wire into the fuse block. I disconnected every fuse/relay behind the coin holder and in the fuse block. The only one that stops it is the 140 amp alt fuse, but the alt is disconnected.

 

[dwh]

Not familiar with the Tacoma wiring plan. If everything is disconnected and there is still a load, then either everything is not disconnected, or there is a short somewhere.

You say the alternator is disconnected. That means that the main charging wire from the alternator is disconnected - but does it mean that every wire to alternator is disconnected? Maybe there is a short in the alternator. Or maybe something else - a computer maybe - getting power through the alternator. Did you try disconnecting the battery charging relay as well?

Dunno...without more info I'm sort of shooting blind.

 

[007]

Yes, the load is there with all wires disconnected from the alternator.

 

[dwh]

What battery isolator do you have? If it has a brain, then it will probably be drawing some power. Should be a lot less than an amp though, unless the solenoid is energized.

I'm confused about this voltage you keep mentioning - saying it's drawing 1a at 10v...exactly how are you getting these readings? The voltage should be whatever the battery voltage is.

 

[007]

Problem solved ( I hope) it appears both Diehard platinum batteries I have are faulty, they are experiencing some type of internal short. I found this hard to believe that both batteries could be faulty, but apparently they were damaged during shipment. The top positive posts on each battery are slightly loose and can spin if you give them a really good grip and some effort. There was evidence that these batteries were damaged when I bought them because the plastic covers (not the case) had small cracks around the posts. The sears guy told me that was very common and only cosmetic. He was wrong, I called Odyssey (enersys) and they told me that the batteries were damaged and that if the top posts can move the battery is shot.

What a diagnostic nightmare! I really chased my tail on this one because I ruled out the battery problem since the issue was still the same after swapping batteries and thought for sure my truck was draining the batts. Oh well, lesson learned.


Thanks for your help dwh, that was very nice of you.