EASY FIX,I recently had a problem with my 2007 maintaining proper power levels in the batteries. I would be driving the truck and the voltage guage would slowly get lower and lower, I stopped the truck and found that mypassenger side battery was boiling. I took the truck to dealer who told me it was a bad battery,so replaced both of them only to have the same thing happen again, so I took it back and the dealer told me it was the computer. My truck being out of warrenty I took it home and looked it over. I found that the cable running from the passenger to driver side battery was corrodded inside the protective boot where the lug connects to the driver side positive clamp. After cutting the lug off and soldering a new one on the problem dissapeared. This problem is fairly common as it turns out, it happens because if ther is no good connection between the two batteries, the computer only senses the passenger side battery and seeing a deficiency in amps it tries to make up for it by overcharging it and boiling it. I hope this helps somebody

 

Thanks for the heads up!!!

 

i had my 12v do the same thing last winter except i was using my boat battery that had froze that winter, used it 3 times and it would be bopiling after 30 mins of charging

 

Thanks for the tip! i may actually be having that problem as we speakchanging a lug this afternoon.