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N601WB's avatar
N601WB
Explorer
Nov 14, 2013

Maintenance Free battery - Blew the caps off?

Sometime last week one of the house batteries (in parallel) blew its caps and deposited acid throughout the battery compartment while plugged in parked at the house. By caps I mean the covers over the top openings. There are two "caps", each covering 3 openings in the top of the battery.

Motorhome has been plugged whenever it was not being used for the last 6 months. I had installed Progressive Dynamics Converter with 4 stage charger 6 months ago and to my knowledge it has been functioning normally. House batteries Costco Marine/RV deep cycle "maintenance free" and are 4 years old. It was 2 weeks since the last trip.

Voltage at the battery after "explosion" was normal 13.4 v when plugged into house 120v power and 12.8 when unplugged.

Only one of the two batteries blew the caps. One of the caps blew right out of the battery compartment and was laying on the ground under the vehicle.

I talked to Progressive and was told that if the converter/charger is providing 13.4 volts, the converter did not cause the problem.

Did I just have a battery that suddenly failed internally?

Still cleaning up the mess with baking soda. Sanding and re-painting will commence this weekend.

26 Replies

  • When I worked on boats I'd see that from time to time. Most of the failures were caused by corrosion or loose terminals. Also with two batteries if on is weak it may cause batteries to overcharge.
  • smkettner wrote:
    When was the last time you checked the water level?


    "Maintenance Free Battery" -- sealed caps.
  • I had the same happening with 6 year old batteries....One exploded in the middle of the night. Scared the bejebbers out of us in a sound sleep.
    Obviously the battery was dead and/or out of acid and couldn't handle the constant charge. New batteries fixed everything...that and a lot of baking soda to clean up the acid in the battery compartment.
  • if you blew only the caps, you got lucky
    the mess could have worse
    time to replace both batteries
    best guess, is that battery lost "TOO MUCH" water from the acid/electrolyte
    the levels got tooo low
    it got too warm while charging, 'H1 gas' pressure built too high in the cells
  • I think the batteries explode when the electrolyte gets too low and somehow there is a spark. I had a battery explode in my Toyota Camry when I hit the key to start it.

    It sucks as there is acid everywhere after they pop.

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