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Only 1 battery is charging? Need advice please

Dieseldad97

Dieseldad97

I now know why.
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Location
Altona, Manitoba Canada
So I did a load test on both batteries and they both tested good although 1 was not as good, but still good. The Alt is less than a year old and shows its charging perfect on 1 battery but not nearly as good on the other.

Is the battery shot? Would a battery not want to accept charge? Any ideas before I spend the big bucks on batteries? They are only 2 years old. Thanks.
 
Gerald, is the cable going to the weak battery good?

Batteries can vary in the fully charged voltage.
 
I was thinking the same thing. one cable on it's way out might just be enough to do it. have you tried swapping the batteries to the other side? that way if it's the battery it won't make any difference but if the cable is bad you'll know right away.
 
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If the voltage with the engine running is the same at both battery posts it is the battery failed. Same voltage means 13.5V with 13.6V at the other battery being a cable problem.

2 years is shot around here anyway...
 
Thanks for the help guys. I cleaned the terminals and tonight I'll charge them up and try this test tomorrow. I'll swap the batts around also to see if the problem follows the weaker battery.
 
btfarm said:
2 years is not long on a battery up north. Is that a rebuild alternator Gerald? Warranteed?
Click to expand...

The Alt was a Mfg rebuilt one from the parts store. It has a warranty, but the way I see it that's not my problem. The truck charges fine, but I feel that one battery (passenger one) isn't accepting the charge.

Funny thing is a few weeks ago I had to boost a car and I used the passenger battery....the car wouldn't turn over at all. I let it "charge" the car for like 5 minutes and it still didn't turn over fast. Mind you it was a VW diesel and it was -35C outside. I figured I'd try boosting off my driver side battery and bang, the car started with no problems.
 
Pass side battery in the Duramax gets all the heat thrown off the fan. Shortens it's life as it nearly always fails first.

Either battery should have started the car so I am thinking you have a positive cable issue to the pass side. Even with 1 battery bad.

Did the battery freeze?
 
I have a sheild and insulation around my pass batt on the dmax but I am curious, would it help to rotate the batteries yearly/every other oil change (~30K fo me). OEM batts lasted to 155K/5.5yrs for my truck.
 
WarWagon said:
Pass side battery in the Duramax gets all the heat thrown off the fan. Shortens it's life as it nearly always fails first.

Either battery should have started the car so I am thinking you have a positive cable issue to the pass side. Even with 1 battery bad.

Did the battery freeze?
Click to expand...

Nice to know. Hey, hahaha everything freeze's around her these days! I'm gonna have a better look at the cables soon.

Thanks for the reply's guys.
 
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