Boiling battery mystery

Should have gotten all 4 batteries replaced........ The 2 old ones will drag the power down of the 2 new ones...or vice versa.......

I had same issue on a volvo i had....

 

Need to check the voltage at the batteries,it sounds like overcharging

 

Alway replace batteries as a set. The smell is coming from a sulfated battery that probably had a bad connection at one time. It causes the one with a bad connection to go dead completely and sulfate the plates. When a good connection is restored to the dead battery, the sulfation turns to hydrogen sulfide, hence the rotten egg smell.

The acid boils in the good batteries because they are being overcharged--the alternator does its darndest to charge the bad one and overcharges the others.

Replace all the batteries, clean every terminal spotless and use GB No Ox on the connections.

 

Well, Yoster told us all 4 batteries tested 12.9, so one wasn't dead, at least not losing charge level. I had this problem right after I bought my '08FL120 Columbia. One batter was boiling, stinking it up. I took that battery out immediately I discovered how hot it was, and got one battery at the Laredo TA. Soon I bought 4 new batteries from Fleet Pride, got a great price but they had no staying power, ran them a while, 1 1/2 years, just bought a set of 4 deep cycle batteries at Freightliner. They're American made, deeeeeep charge, only $109ea.

Anyway, batteries do strange things, strange and dangerous things. They explode, they catch fire, they leak acid all over vital components, so on. It seems to me you need a nice shiny set of new batteries. Soon. I own my truck, and I would never move it with a problem like that, not until I'd got it straightened out. Well. move it to a shop if I had to. I hope you don't encounter any of those problems.

 

Oh. I bought the new strip terminals, from the Freightliner parts, not the cheapo truck stop garbage. And you know, those new terminals made a big difference. No more corrosion, don't work loose, a little cost, about $120/both but I'd do it again for sure.

 

I forgot to say the first battery I replaced, the one that was boiling, had a plate come loose and make a short inside the case. Another battery trick.

 

I agree that batteries should always be replaced as a set. 12.9 volts is high for a bat. at rest. Which means they checked them right after turning the truck off and did not remove the surface charge or they are being over charged. Maybe why it smells? To check voltage on a battery that has not been setting for at least 24 hours. I would recommend starting the truck a time or two or three and shutting it down right away. That will pull the surface charge off and give a more accurate reading. You also have to disconnect each one to test independently.