In the last 4 days I have burned up both batteries in my truck. I replaced the alternator a few months ago and thought maybe it was over charging. I had it checked and they said it's just fine.

First it was the passenger side then drivers side. batteries were so hot I had to let the truck sit over night to get them out. Is there a regulator that controls what battery gets charged and maybe is not turning off? When I replaced each battery I checked the oposite and they were not hot at all.

What should I be checking next?

Kris

Are you having a problem after replacing the batteries? Get a digital multimeter if you don't have one and check the voltage at the batteries when charging. It should be 13.8 - 14.8 volts. If over 15 then yes it is over charging. But what you describe sounds like a battery with a shorted cell. A battery is made up of six cells at 2.1 volts each. Giving you a total of 12.6 volts. When a cell goes bad and shorts you have basicly turned it into a 10.5 volt battery. Then when charging you are charging a 10 volt battery with a 12 volt charge causing it to over heat. The fact that one failed and then the other 4 days later does not come as a surprise. Batteries of the same age often fail at or near the same time.

Are you having a problem after replacing the batteries? Get a digital multimeter if you don't have one and check the voltage at the batteries when charging. It should be 13.8 - 14.8 volts. If over 15 then yes it is over charging. But what you describe sounds like a battery with a shorted cell. A battery is made up of six cells at 2.1 volts each. Giving you a total of 12.6 volts. When a cell goes bad and shorts you have basicly turned it into a 10.5 volt battery. Then when charging you are charging a 10 volt battery with a 12 volt charge causing it to over heat. The fact that one failed and then the other 4 days later does not come as a surprise. Batteries of the same age often fail at or near the same time.

Thank you for the relply. I put a digital volt meter on things and it was about 14.6 + - at both batteries and the Alternator. Even after driving the truck for 20 min.
What you said makes allot of sence. I now have 2 new batteries so I'm going to drive it and hope everything is good. It does spin things better now. both batteries are 1k CCA now. Hope to put a winch on so I went bigger.

Thanks again for the help.

Kris