Battery Charging - Overcharging

Submitted: Sunday, May 07, 2006 at 21:12
ThreadID: 33666 Views:3026 Replies:3 FollowUps:8
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I have a 3 Stage Battery charger. I had it connected to my 105ah Trojan Deep Cycle battery and recharging. I noted it had completed 'Bulk' and was on 'Absorbtion'. Anyway I went out for a few hours.

On returning my wife complained of a smell in the garage. I found the battery charging was smelling of burning so I disconnected the battery charger and while doing it noted it was showing 'Bulk' charge again. When I looked at the battery it had acid bubbling out of the covers of the battery which I opened carefully (very carefully - did not want an acid explosion) to release some of the pressure and gas. I cannot see any signs of problems except for a little acid bubbling out.

I have left it all off for the moment. Any ideas what could have happened? The battery charger is fairly new but I have not had any issues previously.
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Reply By: ZUKSCOOTERX90(QLD-MEMBER) - Sunday, May 07, 2006 at 21:22

Sunday, May 07, 2006 at 21:22
I was alway's led to beleive that you had to take all cover's off the little holes for that particular reason, should not do tooooooooo much damage as i was told they have to boil so to speak to get the acid to circulate,Bob.
AnswerID: 171412

Follow Up By: Coolman - Sunday, May 07, 2006 at 21:26

Sunday, May 07, 2006 at 21:26
That was quick.

While I can see you point I think there is more to it.

1. Has not happened before and I have 2 of the batteries.
2. Nobody removes when the car battery plugs when it is charging?

An the smell. I have a double garage and it was pretty strong.
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FollowupID: 426837

Follow Up By: V8 Troopie - Sunday, May 07, 2006 at 22:59

Sunday, May 07, 2006 at 22:59
I know all about that smell. Happened to me when I was trying to resurrect an elderly Trojan 130Ah battery which had a high internal resistance and would not hold a decend charge.

I have a charger that is capable of delivering 40A.

So I connected the battery to that and wound the 'wick' up a little to about 15V (its a manual, constant voltage, charger).
The current and voltage was monitored and at that voltage a small current started flowing into the battery.

Went shopping then and upon coming back I could smell the battery from outside the closed garage. Opening the roller door revealed a VERY hot battery that was literally hissing acid spray all around it. I quickly switched the charger off and removed myself. It took absolutely ages for the battery to cool down sufficiently so I could take stock of the situation. I rekon I was very lucky that day, I did have the covers off the filling holes which saved my bacon. That Trojan has two large cover thingies which each expose 3 cell filling holes. There was not much liquid left in the battery.

When switching off I noticed the charger was actually putting the full 40A into the battery, whatever caused the initial high cell resistance obviously broke down, allowing all that current to flow.

Sadly, the battery still did not hold a decent charge after that treatment and has long since gone to the recyclers.
Klaus
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FollowupID: 426848

Follow Up By: Coolman - Monday, May 08, 2006 at 09:08

Monday, May 08, 2006 at 09:08
Thanks v8.

The battery is fairly new. Only purchasesd Sept Last year so should be under warranty.

The charger is a 15ah 3 stage charger. I noted it went back to 'Bulk' Charge.

One question I have for other EO members is how do I determine if it is the battery which has failed or the charger?
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FollowupID: 426876

Follow Up By: Mainey (WA) - Monday, May 08, 2006 at 09:47

Monday, May 08, 2006 at 09:47
Coolman, you ask; how do I determine if it is the battery which has failed or the charger?

First contact the charger supplier and advise them of your problem, then advise them if they believe it is working correctly you will then attach it to your cranking battery and will be looking for two new batteries & charger (from them) if it happens again :-(

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FollowupID: 426886

Follow Up By: Member - Mike DID - Monday, May 08, 2006 at 13:31

Monday, May 08, 2006 at 13:31
You need to connect the charger to a known good battery and monitor current and voltage.

The voltage should slowly rise to 14.4 volts and hold at that, until the current reduces to 1/10th of the rated current - 1.2 amp for a 12 amp charger. Then the voltage should drop suddenly to 13.6 volts.

Mike
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FollowupID: 426923

Follow Up By: Member - Mike DID - Monday, May 08, 2006 at 13:33

Monday, May 08, 2006 at 13:33
i.e

The voltage should slowly rise to 14.4 volts - Stage 1

and hold at that, until the current reduces to 1/10th of the rated current - 1.2 amp for a 12 amp charger. - Stage 2

Then the voltage should drop suddenly to 13.6 volts. Stage 3

Mike
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FollowupID: 426924

Follow Up By: Shaker - Monday, May 08, 2006 at 16:12

Monday, May 08, 2006 at 16:12
"That smell" is both poisonous & very explosive, be careful!
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FollowupID: 426956

Reply By: Flash - Tuesday, May 09, 2006 at 16:24

Tuesday, May 09, 2006 at 16:24
Understand the battery is fairly new...
however one dud cell will cause the problems you describe.
With the voltage down on one cell, the charger tries to bring it up and therefore overcharges the other cells-
just a possibility
Cheeers
AnswerID: 171735

Reply By: DesC - Tuesday, May 09, 2006 at 18:48

Tuesday, May 09, 2006 at 18:48
what brand of smart charger was it? mine is a durst and has tumbler switches so you can program the boost and absorption modes so that it will float after 4 hours or 8 no matter what the condition of the battery is to stop events like that from burning your shed down!
AnswerID: 171777

Follow Up By: Coolman - Tuesday, May 09, 2006 at 20:53

Tuesday, May 09, 2006 at 20:53
It is a Smart Charger BC-012-15A.

I will have a look at the specs to see what it says about safety but on the weekend I will put it back and and see if a cell on the battery has shorted.

It will make me think twice about 'just leaving it' in future. It was bloody hot and smelly. I think the gas is Hydrogen so the chances of ignition are high. Don't fancy my garage and Paj going the same path as the Hindenberg.
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FollowupID: 427277

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