battery nightmares

pmills42255 · #1 03-09-2003

why would a gel battery boil?
I have a bank of 6 6volt batteries. the charger took a long time to get them going, but once it did, one of the batteries got quite hot and sounded as if it were boiling. Can this hurt the battery?
Paul

jklewissf · #2 03-09-2003

The battery that boiled was overcharged. This does not necessarily hurt a flooded battery and should be occaisonally done on purpose to "equalize" the batteries.

My concern would be that only one of the batteries in the bank boiled.

I would check out the specific gravity of that battery before discharging it again.

Nigel Calder''s book "Boat owners mechanical and electrical manual" has a very good discussion of all of this.

jklewissf · #3 03-09-2003

Sorry, I missed the fact that they were gel cells when I responded before. The boiled battery is toast. It may have been charged at too high a voltage. Most gel cells wont tolerate charging voltages much above 14 volts. If you regulator allowed them to go to 14.2 or 14.3 you may have fried the battery. There is no cure.

There are little vents on the tops of gel cells. When the battery boils these vents are forced open and you should see little bits of stuff accumulated around the holes. This is a sure sign that the battery has been trashed.

pmills42255 · #4 03-09-2003

thanks J,
I was wondering if the battery was toast before, and that is why the entire bank was dead after only three months. I will disconnect the last 2 batteries and work with the other 4 to see if that helps. The charger seemed to fluctuate between 14.2 and 14.8 volts. maybe the battery temperature had something to do with its being that high? The load comes off the other end of the bank, so maybe those batteries delt with the voltage better?

The charger is a Heart Inverter and seems to be state of the art.
If the entire system is dead in two weeks when I go back, maybe the one is taking all the others down?
You sound pretty knowlegeable, thanks for your insight!
Paul

h37skipper · #5 03-10-2003

The Heart inverter/charger should not hurt the Gels IF properly configured. The control panel on my Freedom 20 has dip switches on the back. These need to be set for Gels. Then you should not see a charging voltage over 14.2.

lecomte38 · #6 03-10-2003

another happy gel customer.

Cut your losses now and buy a set of Trojan T105s.

LEAD/ACID RULES

Trojan Man

tsenator · #7 03-10-2003

14.8 Volts on a Gell Battery ?...

Thats a bit too high, no wonder they fried. I think the typical charge voltage @ 20deg C should be closer to 14.1 Volts

Here is a link for Deka Prevailer batteries, and it gives some info on charge voltage. This is typical for Gell Cell''s .http://www.sonnenschein.org/Prevailer.htm

tsenator · #8 03-10-2003

ps. Try taking out just the battery that boiled (well actually the 2 of them that makes up a 12Volt bank) and then see what your remaining battery output is like. If you are lucky, maybe you are correct and only one or 2 batteries are bad.

windship · #9 03-15-2003

I agree with lecomte 38.Gells and AGM''s are a waste of time and money. Why make things more complicated and expensive then they have be? Your best ratio of AH to pennies is lead acid 6 volters but I would go with the Interstate 6 volt...they are the heavyist batt on the market.

Dennis

jklewissf · #10 03-16-2003

Newer heart inverters do not have dip switches. The appropriate charging protocol is selected via push buttons on the front of the unit. If you had the heart set for flooded batteries, it will trash the gel cells.

Another source of damage is the regulator on the engine alternator. If it is the stock alternator that most engines come with, it will probable be internally regulated and set for flooded batteries. If you left for a cruise after the batteries were fully charged at the dock, the alternator would immediately start pusing the voltage up to try to cram more amps into the batteries.

Gel battereis should not be charged using an internally regulated alternator unless you know there is some way to adjust the regulator for lower voltages.

I have used flooded batteries, gel cells and am now giving AGMs a try. All have their advantages and drawbacks. The negative on flooded cells is their need for maintenance. On my last boat I had to use a mirror and flashlight to see if they needed water...That was a big "pita" . Flooded cells bring with them the risk of injury by the corrosive electrolite. The can also be trashed by being completely drained. They are cheap and it is possible to monitor their condition with a hydrometer. They also (as someone pointed out, give you the most amp hours per buck) Now that sealed alternatives are available I wont use flooded batteries.

Gel Cells are sensitive to charging voltage but have more capacity than AGMs. There is still debate of which of the sealed options provide more cycles in their lifetimes. BTW, cycles is not the name of the game, total amp hours in the battery''s life is the thing to worry about for economic reasons.

AGMs have the advantage that they can be installed in any position and dont loose capacity as a result. Gels can be installed on their side but loose about 10% of their capacity. AGMs have very high exceptance rates. This is a double edged sword. You can charge faster but need to watch temp and have some way to reduce alternator output (especially in hot weather). AGMs can be treated like flooded batteries in terms of the voltages they will tolerate. They have slightly lower capacity than flooded cells.

I just put 5 4d agms on my new boat. The are charged through the heart inverter/charger and using a balmar high output alternator and max charge regulator. I installed the temp monitoring option from the heart. It senses battery temp and warns of problems. The balmar max charge has two temp sensors. One is on the alternator (to prevent it from overheating when charging greatly discharged batteries, and one to the batteries themselves. If the max charge senses elevated battery temp it halves the output of the alternator.

If you have indeed trashed some of your gel cells maybe you can get by on the remaining cells for a while. Dont put new gels in a bank with old ones. The old gels will quickly drag your new batteries down to their state of health.

If you have a stock alternator and dont want the expense or hassle of changing it out, use flooded batteries or AGMs which can handle the output of the alternator. Make sure your heart is set for the type of battery you have chosen. If the heart is set for gels it will consistiently undercharge your flooded batteries.