Hot Battery

[ianjory]

Recently I found one of my two wet house batteries with the two covers off, and the lead exposed. I filled the batteries up with distilled water and put the covers back on. 24 hours later, the battery was very hot to touch. What has happened here? is this battery toast? Please help!!

[btrayfors]

Yes, it's toast!

Running a battery dry is a sure way to kill it. And, if it's hot, that's just another clear sign.

When you replace it, replace BOTH batteries.

And, then, take care of them.

I suggest that at a bare minimum, you download and read carefully the "Trojan Batteries User's Guide" at the bottom of this page: http://www.trojanbattery.com/Product...lProducts.aspx

Bill

[ianjory]

Thanks for that. Any idea why it ran dry though? Could it be age? How long do batteries last in general?

[Ex-Calif]

Yep - Hot to touch batteries can be very dangerous.

In the worst case those lead plates you see buckle and short out.

Very bad.

[Chief Engineer]

Ifyou found them with the caps off.....you may have had a short or spark that ignited the hydrogen.....bad news indeed

[Ex-Calif]

Originally Posted by Chief Engineer

Ifyou found them with the caps off.....you may have had a short or spark that ignited the hydrogen.....bad news indeed

Good point - Before slapping in new batteries you'd want to know if you just had old worn out batteries and one shorted or if you had a charging system anomaly.

Certainly don't want to fry new batteries if the charging system is going runaway.

Might use the remaining single "good" battery to do some investigating before ultimately replacing both.

[foggysail]

I believe the battery's electrolyte does not "boil" under load (discharge), only when charging. Charging at high currents will cause heating and if overcharged, will boil the electrolyte. I suggest you check out your charger.

Foggy

[btrayfors]

All good advice above.

Flooded batteries can run dry in the normal course of events, due to several reasons including overcharging. Some evaporation can take place as well. They need to be checked regularly and topped off to the proper level (about 3/8" to 1/2" above the top of the plates). HydroCaps or WaterMiser caps can reduce the amount of electrolyte loss, thus the intervals between topping off. Still, even with these caps, it's a very good idea to check the electrolyte levels on a regular basis.

Flooded batteries in cruising service have a lifespan of 3-5 years on average. Bad treatment can kill them in less than a year; exceptionally good treatment can extend their life by a few years.

Again, read the Trojan User's Manual. Pay careful attention to the charging recommendations. Undercharging can kill a battery as well as overcharging. You want to be sure that the onboard devices for charging (battery charger, alternator, solar panels, etc.) are well suited to the type of batteries you install. A mismatch here can dramatically shorten the life of your batteries.

The sad fact is that many -- perhaps most -- boat batteries don't just die. They are murdered. The "usual suspects" are:

- bad installations;

- neglect;

- improper charging and charging devices;

- chronic undercharging leading to sulfation of the plates and loss of capacity;

- cycling too deeply on a regular basis;

- contamination of the electrolyte thru improper care (leaving caps off, allowing dirt or extraneous materials in, not using distilled water to top off, etc.);

- stratification of the electrolyte caused by undercharging and lack of use and movement; and

- physical damage to the plates caused by overcharging, corrosion, or precipitates building up underneath them and shorting them out.

Educate yourself, take care of your batteries, and you'll have a much more positive experience next go-round!

Bill

[richardhula]

Originally Posted by foggysail

I believe the battery's electrolyte does not "boil" under load (discharge), only when charging. Charging at high currents will cause heating and if overcharged, will boil the electrolyte. I suggest you check out your charger.

Foggy

Its almost a cert that when a wet cell battery gets unusually hot under charge its because a cell has gone short circuit. This is usually caused by lead dropping off the plates & collecting at the bottom of the cell, shorting all the plates together. Assuming it was a 12 volt battery, you suddenly have a 10 volt one receiving charge for a 12 volt one.

Whatever charges such a battery will just see it as a seriously flat battery & attempt to get the voltage up by dumping max amps into it in bulk/mass charge mode if it has a smart controller. This will cause electrolyte to boil or nearly so & battery will rapidly gain a high temperature. Its important you have a battery temp sensor linked to the charger so when it senses high battery temperature it will shut down or at least go into float mode.

Other tell tale signs of failed battery are a sharp acidic or maybe hydrogen sulphide (bad eggs) smell. The water element of the electrolyte will rapidly boil away leaving remaining cells dry or nearly so.

Whats worse is that if this battery is part of a domestic battery bank, even after disconnecting the charge source(s), the remaining batteries will dump current into it in a vain attempt to equalise the voltage. In all such cases it must be isolated a.s.a.p.

Checking open circuit voltage on such a battery will probably show around 10.5 volts if it was a 12 volt one & a single cell has gone down. Absolutely no point in trying to revive it.