Are these batteries beyond recovery?

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Modulation

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2 Trojan 100amp batteries fitted, both about 30 months old - they've been brilliant. Trouble is that this winter my Halfords charger, which the directions say can be left connected all the time, actually failed. Instead of cutting out and going into top-up mode, it just kept on trying to charge. By the time i realised there was a problem, the batteries were seriously low on electrolyte, so much so that each took 3/4 litre of water to cover the plates again. I'm going back to the boat tomorrow with a multimeter to measure voltage.
I know that overcharging causes gassing, but do you think that I can do anything to help recover these batteries? At £160 a throw, this is hurting me! And yno I am never going to leave a charger permanently connected.
 
brendanbergin said:
2 Trojan 100amp batteries fitted, both about 30 months old - they've been brilliant. Trouble is that this winter my Halfords charger, which the directions say can be left connected all the time, actually failed. Instead of cutting out and going into top-up mode, it just kept on trying to charge. By the time i realised there was a problem, the batteries were seriously low on electrolyte, so much so that each took 3/4 litre of water to cover the plates again. I'm going back to the boat tomorrow with a multimeter to measure voltage.
I know that overcharging causes gassing, but do you think that I can do anything to help recover these batteries? At £160 a throw, this is hurting me! And yno I am never going to leave a charger permanently connected.
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All you can do yourself is try to charge them, then if they appear to charge OK see if they hold the charge and if they perform satisfactorily.

Presumably not used for engine starting
 
My method when I leave the boat is to use the charger on the boat connected via a 7 day timer. This winter with the ultrasonic antifouling running I left it set to come on twice a week for about 90 minutes a time. That has worked fine. If the boat had been on the hard with nothing turned on I would have set it to come on once a week.
 
If the batteries boiled and lost electrolyte then you need to replace electrolyte not just add water.

Check the specific gravity and if necessary replace the entire electrolyte. Worth a try for the costs involved.

Tony.
 
Jabs said:
If the batteries boiled and lost electrolyte then you need to replace electrolyte not just add water.

Check the specific gravity and if necessary replace the entire electrolyte. Worth a try for the costs involved.

Tony.
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If the batteries just gassed and no electrolyte was physically lost then adding water only is the correct thing to do.

If electrolyte was lost they'd be standing in pools of acid. Neutralizing that would be the 1st priority.

BTW it will take sometime before the added water has fully mixed with the remaining acid
 
Jabs said:
If the batteries boiled and lost electrolyte then you need to replace electrolyte not just add water.

Check the specific gravity and if necessary replace the entire electrolyte. Worth a try for the costs involved.

Tony.
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Sorry wrong, the water boils off leaving concentrated eloctrolyte
Stu
 
Jabs said:
If the batteries boiled and lost electrolyte then you need to replace electrolyte not just add water.

Check the specific gravity and if necessary replace the entire electrolyte. Worth a try for the costs involved.

Tony.
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NOT THE CASE.

Just top up with distilled water as normal. You will have done some damage but if they are golf cart type or traction batteries the plates are thicker and damge is less severe.

Top up and use, I guess you will soon see if you have enough capacity left.
 
Just installed a CTEK M100 charger which is electronic and boasts it is designed to be left on to care for your batteries.

It has a recondition function which has successfully revived one of my batteries when I left it on and ran it flat.

If you are replacing I would recommend investing in an intelligent type of whichever brand you choose
 
Overcharging flooded lead acid batteries can harm them in a variety of ways. If a lot of energy is put in quickly the plates can heat, buckle, erode and short. Lower level of energy going in causes less heat but you still get gassing and that can erode the paste from the plates. The second is more likely as it sounds as if the charger was only putting in a small current but voltage was too high.

So you may have lost some material from the plates and that will reduce capacity and also increase the likelihood of a short in a cell.

I'm certain that other people will provide more information on other types of damage but I believe these are the most important. Leisure batteries will probably be affected more than Deep Cycle batteries.

You mentioned 100A Trojan so I think you are using something like 27TMX Trojan batteries. I considered buying these but Trojan specs. quote a CCA figure so that made me think that they were actually "Leisure" batteries. I asked them for further information and they sent graphs of cylces vs. Depth of Discharge. That confirmed that T105s were expected to last for more than twice the cycles of a 27TMX. So I think they aren't as suited to deep cycling as T105s.

Best thing would be to recharge fully, do a discharge test and monitor the voltage (5A draw for 20 hours if still holding 100% charge).
 
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Just add distilled water. (think you have done that bit)

lightly charge, it will help it all mix again.

if charger was of low output, you might be lucky and not too much damage done.

been there, got another 2 years out of them, 5 in total.
 
It might be worth checking your insurance. No doubt there is an exclusion somewhere but this is an "accident" of sorts, not negligence, so they might pay up.
 
Many thanks for replies - they've given me plenty to work with.
And yes - one of them was my starter battery - and it was really struggling the last time I was on the boat.
 
Mistroma said:
Overcharging flooded lead acid batteries can harm them in a variety of ways. If a lot of energy is put in quickly the plates can heat, buckle, erode and short. Lower level of energy going in causes less heat but you still get gassing and that can erode the paste from the plates. The second is more likely as it sounds as if the charger was only putting in a small current but voltage was too high.

So you may have lost some material from the plates and that will reduce capacity and also increase the likelihood of a short in a cell.

I'm certain that other people will provide more information on other types of damage but I believe these are the most important. Leisure batteries will probably be affected more than Deep Cycle batteries.

You mentioned 100A Trojan so I think you are using something like 27TMX Trojan batteries. I considered buying these but Trojan specs. quote a CCA figure so that made me think that they were actually "Leisure" batteries. I asked them for further information and they sent graphs of cylces vs. Depth of Discharge. That confirmed that T105s were expected to last for more than twice the cycles of a 27TMX. So I think they aren't as suited to deep cycling as T105s.

Best thing would be to recharge fully, do a discharge test and monitor the voltage (5A draw for 20 hours if still holding 100% charge).
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Thanks for this. Actually from memory they ARE deep cycle batteries - type SCS150 100AH. So there's a possibility the thicker plates will have helped. The real problem is I don't know if the charger failed last October, or this March - or any point in between!
 
I get really irritated when peeps don't read what I said and read what they think I said.

If electrolyte has been lost, it needs to be replaced with electrolyte. If water has evaporated, water needs to be replaced.

So, if the batteries have boiled over and lost electrolyte, it needs to be replaced which is what I said in the first place!

Tony.
 
Jabs said:
I get really irritated when peeps don't read what I said and read what they think I said.

If electrolyte has been lost, it needs to be replaced with electrolyte. If water has evaporated, water needs to be replaced.

So, if the batteries have boiled over and lost electrolyte, it needs to be replaced which is what I said in the first place!

Tony.
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They dont "boil over" and lose electrolyte, they sit and fizz and boil off water. Stop digging!
Stu
 
skipper_stu said:
Sorry wrong, the water boils off leaving concentrated eloctrolyte
Stu
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Will you please read what I said?

I said that if you have lost electrolyte, you need to add electrolyte.

Not water.

If the electrolyte has evaporated, add water.

Why is that so unclear?

Tony.
 
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