I have a 1978 half ton with a 390 ci engine. I was given a marine grade, deep cycle battery and thought because my truck battery was old and getting weak i would replace it with this one. Since then my voltage has died. so i replaced it. it has worked for a few weeks now, but the other night i was driving home from work when i lost power to the entire truck. lights, stereo, ignition etc..... Today i started her up, ran it for a while, and tinkered with it. After i shut it down i can hear the battery hissing and the sides looked bloated. i relaize this can be dangerous, so i left well enough alone for now. am i having these issues because my charging system, or ignition system is not designed for such a large battery?

 

Bad battery. It could explode in your face. It happened to my brother in law but didn't change his looks that much.

Be careful. Take it to a battery store that can check your charging system and battery.

 

What he said.

 

Whatever you do, don't make a spark. That hissing was almost certainly hydrogen gas. Ever heard of the hindenberg? Picture that with a spray of sulfuric acid for good measure.

 

Swollen Battery... kinda sounds like a truck std

 

you are over charging it . Wear a safety glasses working on it . I almost go blind because of a battery Explosion . while removing the terminals that created the sparks . good luck,,

 

Your battery is pregnant. In about 9 months you'll have a litter of triple a's in your engine compartment.

 

^ hahaha

 

The size of the battery has no affect as long as it is a 12 volt battery.The symptom you describe is sevier over charge this can be due to a faulty regulater but is most likely caused by an internal short in one cell of the battery. this makes it for all practicle purpose an 10 volt battery and the truck is overcharging the other 5 cells trying to bring the voltage back up. abattery in this state will often start the truck but as it runs it will get hot, vent excessive [and explosive] hydrogen gas and if the pressure inside gets to high could rupture the case and spray acid all over. you need a new battery and have the charging system voltage checked [only after installing a known good and fulley charged battery]

 

Thanks