Battery Boil & Water

[sailorboy1]

theories as to why battery 2 boils over and uses more water than the rest

[a64pilot]

All three cells?
My swag is battery 2 has a higher resistance, but I have no idea.
I was going to say bad, but what makes it bad if it has the same capacity as the rest, I’d assume it doesn’t.
But that means a cap check and I know that’s not likely and understand why.

Maybe try swapping it with a different battery to see if the water consumption follows it, that ought to eliminate wiring?

[ramblinrod]

Originally Posted by sailorboy1

theories as to why battery 2 boils over and uses more water than the rest

Shorted cell.

[BlackHeron]

Try swapping caps if they are the quick-link ones. Could be one is not sealing well.

Check all connections for a bad one, even a poorly crimped lug or any hidden corrosion inside. Check for excessive wiggle in the lug. Maybe hit them all with an IR thermometer looking for any hot spots on the wiring at high rates of charge

Maybe #2 is getting warmer because of position? In the corner and not shedding heat as well, an IR thermometer over everything should show you any hot spots.

But my gut says bad cell, sulfation, shorted. Are all the batteries from the same manufacturer and dates? Are any older than the rest? Best to be all from same lot when you buy them.

When I bought my four GC-2 6v batteries for my house bank I dug through the whole pallet at Sam's Club to find 4 matching ones all from the same production lot and manufacturer date. I was amazed that this stack had ended up together from so many different lots and mfg dates.

[a64pilot]

Shorted cell would have just that one cell using water, and boiling wouldn’t it?

[ramblinrod]

Originally Posted by a64pilot

Shorted cell would have just that one cell using water, and boiling wouldn’t it?

Nope.

[ramblinrod]

Take the charge voltage off.

Disconnect the good parallel bank.

Apply a decent load (around 40 A) for 15 minutes, remove it for 15 minutes, and measure the voltage across the battery. If it is close to 4.2 Vdc and no where near 6.3 Vdc, it’s likely a shorted cell.

This can be a dangerous situation as that side of the bank will drain the other side, boiling all the time. At some point you can enter a thermal runaway situation that may cause a whole world of hurt.

[BlackHeron]

Even before charging, a battery with a bad cell should show a fairly different voltage across it compared to the others in the bank. A hydrometer test should show a significantly different specific gravity as well. Either result would be a red warning flag.

[s/v Jedi]

IR temperature gun to quickly show hot spots. Disconnect cables and measure voltages to confirm.

[sailorboy1]

wouldn't a shorted cell be see in capacity/voltages, because i'm not

its been this way for 3 years since the batteries were new

[markcouz]

The best way with your flooded cells is to buy a dirt cheap hydrometer and test the specific gravity in each cell. You don't have to know much, simply compare results.

I think you will find that 1 cell in batt#2 has failed, causing the others to overcharge and boil - but whatever the result the hydrometer will reveal all.

[markcouz]

If it is cell failure then sort it out fast, ot batt1 will soon follow suit.

[Wood]

FWIW -Depending on where your batteries are located using a standard hydrometer can be difficult to impossible. I use this one:






It gets into tight places and has temperature compensation.

[Wood]

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[sailorboy1]

i use a refractometer