Boiling the Batteries?

[Myknjul]

I have 3 year old 12V deep cycle batteries on my 2014 Beneteau. Over the weekend we serviced and topped off the house bank. One of the cells had the top of the lead exposed. Since finishing, the batteries have beed charging like crazy and are hot as a firecracker. And the smell is noxious. How could batteries that were fine before topping off with distilled water, now seem to be on runaway charge. This afternoon I turned off the charger to let them cool down a bit.

Once cool we tested them and first thing we noticed is that the water is very dark. Secondly, the state of charge was off the scale for our cheap tester. Any thoughts as to what's going on.? I'm afraid we will get gassed by these things.

[TurninTurtle]

You've done something to compromise the batteries. The electrolyte should never change color.

Did you use distilled water or tap water? Often tap water will have chemicals in it that can damage the battery. Just a little can cut the life of a FLA battery by years.

"Hard" (high mineral content) water will destroy a battery very fast.

[Myknjul]

Thanks for responding. It was distilled water that was used.

[Myknjul]

Just triple checked. It was distilled water.

[leftbrainstuff]

Sounds like you have a contaminant in your batteries.

Did somebody by chance feed them salt water?

There is no way to clean or remove contaminated electrolyte that penetrated the plates.

You could try draining and refilling with distilled water. If that doesn't work they go in bin 13.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[TurninTurtle]

Actually the only cure for contaminated electrolyte is dismembering the battery and recasting the plates... New electrolyte, new plates, new separators. ( a new battery in the old case)
The separators are contaminated.

Drain and refill with distilled water just leaves you with diluted contaminated electrolyte.
Draining and refilling with new electrolyte leaves you with contaminated electrolyte.

Salt water (chlorine contamination) can result in DEADLY outgassing.

[Omatako]

Originally Posted by leftbrainstuff

You could try draining and refilling with distilled water. If that doesn't work they go in bin 13.

Filling them up with distilled water will have disappointing results and will definitely cause the owner to bin them. Batteries need a specific dilution of acid/water to function. They will not charge with just distilled water.

I had ten-year-old Trojan 6v batteries that were consuming large quantities of water. Decided to replace them and when I took the old ones in for disposal, the man in the battery shop dropped one on top of another and punctured the case on the terminal bolt. The acid/water that came out was pitch black.

I believe for no reason than above that black electrolyte and high water consumption are the product of batteries that are done. Someone will no doubt have a more technical explanation