Volvo Boiling batteries?

Are you running the engine and an apu at the same time? Or, do you have an apu with an overcharging alternator?

 

You can isolate the B+ at the alternator with the truck off to prevent arcs/surges. Then start it and check the alternator output then. It's coming out anyways.

The truck wouldn't be shutting down unless there was a high voltage. A voltage regulator won't let more than 14.5V pass unless it's bad. Over charged batteries from a bad cell won't shut the truck down. They can boil from overcharging, but they won't reach the voltage to shut it down. The shutdown is from high voltage that the truck is designed to shut down to protect the ECM and other sensitive electronics.

Since the batteries were boiling, do a visual inspection of each cell and refill with distilled water right above the plates. If you see a cell that is dry, then it might be bad. You won't know unless you do a load test on it.

dave if it has an apu, they both won't run at the same time unless someone hooked the apu up wrong. The trucks ACC energizes a relay that cuts power to the apu. Unless someone straight wired it, they can't run at the same time.

 

Radio shack used to sell a tester you could plug into your cigarrette port. It would tell you whether your system was running correctly. Otherwise if you are over charging, check your alternator ground. If your alternator doesnt see enough ground voltage it will overcharge as well.

 

If there is a Harbor Freight in your area you can buy a voltage checker which will check your batteries and charging system for about $10-15. If you have an Autozone near you, they will check it for free.

 

just change the alternator,I had the same problem/change the batteries too/

 

hmmm what does squeezing the batteries do??