auxillary battery boiling

Submitted: Sunday, Mar 24, 2013 at 14:21
ThreadID: 101269 Views:2575 Replies:4 FollowUps:5
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My aux (deep cycle) battery keeps boiling - even when down to top of plates , my starting battery doesn't - so that tells me the alternator voltage is ok . Is the battery on its way out ? It is connected to two solar panels as well (running Waeco) - regulator appears to be working ok - limits voltage to around 13.4 volts .
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Reply By: Dennis Ellery - Sunday, Mar 24, 2013 at 14:46

Sunday, Mar 24, 2013 at 14:46
Some flooded deep cycle batteries are lead antimony – They are good quality, long life and ideal for golf carts, forklifts and in the back of 4WD. They don’t like the high temperature under a bonnet and will boil themselves to death. By the way what make is it?
AnswerID: 507482

Reply By: River Swaggie - Sunday, Mar 24, 2013 at 15:11

Sunday, Mar 24, 2013 at 15:11
I had the same issue with mine awhile back..Dont they boil,Took it out and gave it the ass..Couldn't trust it under my bonnet..

I bought another Century 4wd battery and its been brilliant..
AnswerID: 507484

Follow Up By: Dennis Ellery - Sunday, Mar 24, 2013 at 21:02

Sunday, Mar 24, 2013 at 21:02
Your Century 4WD is calcium/antinomy lead and they handle heat a lot better than lead antinomy.
FollowupID: 784781

Reply By: Member - Rich - Sunday, Mar 24, 2013 at 18:26

Sunday, Mar 24, 2013 at 18:26
Had the same a couple of weeks ago.

I took it to a local battery place and they reckoned I dropped a cell.

Either way it was stuffed and had to be replaced. I had had it for awhile.

I had liquid squirting out of the battery and realised it by the gas smell it generated.

AnswerID: 507491

Reply By: The Bantam - Monday, Mar 25, 2013 at 10:55

Monday, Mar 25, 2013 at 10:55
There are a couple of issues that could be in play here.

Any screw top battery needs topping up regularly, fluid loss is simply a matter of fact in non sealed batteries.....and should be charged no higher than 13.8 volts on a continuous basis..or....excessive fluid loss will occur.

It you want to be technicaly fussy, if the temperature is increased above nominal (typically 25C), the charge voltage should be reduced to limit fluid loss to a tolerable level....this reduced charge voltage could be as low as 13 volts.....don't worry too much about this....but realise it is a factor

AT NO TIME should the electrolite be allowed get below the level of the plates

Most of the modern electrical systems and most new replacement alternators will charge at around 14.2 to 14.5 volts, more suitable for sealed batteries.

Sealed batteries have been chemically modified to reduce gassing and electrolite loss then sealed in a way that the gasses generated are recombined under pressure to return fluid to the electrolite.
They will tolerate higher continuous charge voltages than screw top batteries.

Now having said all that....are you sure about your charging voltages? sure

Then are we talking about more or less even fluid loss across all cells of the battery?..if one cell is consistently lower than the others its well and truly on the way out.

Now this old is it...these things don't last forever, particularly in situations where they are deep cycled and in hot places.

I read paper on batteries the other day, and they showed that the life of a high end stationary battery could be reduced from its design lifespan of 15 years in an ideal situation to 60 days with heat and deep cycling

There are situations where a battery may gas excessivly toward the end of its life.

Some checking and further investigation required.

OH...this deep cycle it intended for automotive applications.

OH OH....BTW have you checked the specifications for this deep cycle battery....what is its "maximum initial charge" rate...if you are exceeding the specified maximum initial charge rate on an screw top will be gassing excessivly and suffering fluid loss.

In many situations I question the selection of a deep cycle battery......the name "deep cycle" is deceptive.......

Truth is Deep Cycle batteries are deigned to work with long charge discharge cycles where they may be discharged over a long period, stay at a low state of charge for long periods and be recharged over long peroids.....AND hold charge for long periods.
In short batteries very large in comparison to the load and the charging source.

If you are hitting a battery hard and discharging it over pretty short periods, then hammering the charge back in......that is more like a starting, lighting ignition battery application.......a deep cycle battery will tolerate being hammered no better than a decent cranking battery

AnswerID: 507531

Follow Up By: lizard - Monday, Mar 25, 2013 at 13:15

Monday, Mar 25, 2013 at 13:15
The battery is approx 3 years old , still holds 12.7 volts after being disconnected for awhile , I think temperature may be a factor , been 40'c here in Newman for past week or more , so the 13.5 solar may have done it - battery has been on float most of the time .... all cells lose electrolyte at the same amount .... I think I will swap it for one of my Van maintainence free batteries
FollowupID: 784822

Follow Up By: Member - J&R - Monday, Mar 25, 2013 at 13:56

Monday, Mar 25, 2013 at 13:56
3 causes for battery electrolyte boiling, as distinct from standard or elevated evaporation. Past its use by date (sulphated), faulty cell and overcharging.
Charge rate anywhere between 13v-14.4v....ok
2 minute diagnosis by an experienced auto electrician.
FollowupID: 784824

Follow Up By: bigfellabrian - Monday, Mar 25, 2013 at 21:23

Monday, Mar 25, 2013 at 21:23
Jr is right, check your solar panel regulator over charge will kill, also temp and cell drop.
FollowupID: 784870

Follow Up By: The Bantam - Monday, Mar 25, 2013 at 22:24

Monday, Mar 25, 2013 at 22:24
Sorry J&RI dont care how long you've been an autoelectrician, experience, manufacturer documentaion and standard engineering texts tell me that voltages above 13.8 volts will result in excessive gassing and fluid loss in non sealed batteries.

That is why 13.8 volts in the universally accepted long term float charge voltage for 6 cell lead acid batteries.

In vehicles you can often get away with higher charge voltages because often the charge is far from continuous.

As I said...look up the specifications for the battery in question....many deep cycle batteries have quite low maximum initial charge rates.

Lizzard mate...if its a decent solar reg, you should be able to adjust to a different charging profile or reduce the charging voltage.

FollowupID: 784876

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