How long to open batteries take to recover from overcharging?

[Piran]

My Trojan open batteries were being overcharged, thought to be due to a fault with my solar controller. Since Friday (4 days ago) they have been disconnected from the solar and haven’t been charged by the engine. Their voltage is now 12.6 and they are still displaying symptoms of over charging such as make little squeaking noises and produce a small amount of bubbles seen rising from the plates. 
 

At no point have they been hot or making a gassing sound when opening the terminals. 

 

Is this normal? How long can I expect them to bubble or might something else be going on?

[Tony Brooks]

The bubbles would make me suspect the start of a shorting cell but 3 days and just dropped between 0.1 and 0.2 volts does not go  along with that, if it is bubbling I would have expected a larger drop. i would have expected any gassing from over voltage to have got out within a day or so.

 

Why do you suspect overcharging? what was the maximum voltage. A shorting cell will gas cause gassing undercharge and might may someone suspect it is over-voltage.

[cuthound]

1 hour ago, Tony Brooks said:

The bubbles would make me suspect the start of a shorting cell but 3 days and just dropped between 0.1 and 0.2 volts does not go  along with that, if it is bubbling I would have expected a larger drop. i would have expected any gassing from over voltage to have got out within a day or so.

 

Why do you suspect overcharging? what was the maximum voltage. A shorting cell will gas cause gassing undercharge and might may someone suspect it is over-voltage.

 

I agree.

 

Overcharging results in excessive gassing, high temperatures and loss of active material from the plates.

 

I would say the OP's batteries are probably Ok.

 

I can't explain the squeaking noises or the bubbles coming from the plates after a couple of days of being off charge. Perhaps a flatulent mouse is trapped between the plates? 🤔😅

[Piran]

Thanks for the responses! Haha I did wonder about there being a mouse down there but definitely seems to be the batteries! It is odd... is it possible that one of the batteries could be doing less well than the others causing current to pass between them?! Not sure if that would explain the continued bubbling. 

 

Would someone mind explaining what a 'shorting cell' means?

 

Cheers again! 

 

 

[Tony Brooks]

Just now, Piran said:

Thanks for the responses! Haha I did wonder about there being a mouse down there but definitely seems to be the batteries! It is odd... is it possible that one of the batteries could be doing less well than the others causing current to pass between them?! Not sure if that would explain the continued bubbling. 

 

Would someone mind explaining what a 'shorting cell' means?

 

Cheers again! 

 

 

 

A shorting cell occurs when the positive and negative plates manage to make contact by some means so electricity can "leak" away. This will also discharge the other cells and batteries. It will cause that cell to gas   more then the rest while on charge and might also cause gassing when off charge. That is what you are seeing.

 

the short may be caused by:

a build up of shed plate material connecting the bottom of the plates

A hole being worn in the separators that sit between the plates.

 

In a bad case the short can be so bad it boils the cell dry and then the battery might explode.

[Piran]

Thanks @Tony Brooks. The batteries were installed in 2016, trying to gather if that makes them quite old and prone to plate issues? 

As the charge is dropping at a slow rate does that make it less likely there is a leak of that sort?

 

 

[nicknorman]

Trojan wet cell batteries are pretty tolerant of being overcharged. Did the electrolyte level drop noticeably, eg so the top of the plates was exposed? If not, I don’t think the overcharge will have been significantly detrimental. But if you haven’t already done so, do check the electrolyte level!

[Tony Brooks]

11 minutes ago, Piran said:

Thanks @Tony Brooks. The batteries were installed in 2016, trying to gather if that makes them quite old and prone to plate issues? 

As the charge is dropping at a slow rate does that make it less likely there is a leak of that sort?

 

 

 

Yes but that depends upon the degree of the short and the voltage being around 14.4 volts so not if it has dropped below that. It wont drop on a standard alternator but may with added gizmos or with solar or mains charging.

 

I would expect Trojans to last longer than five years as long as they have been properly looked after. As Nick says check them for electrolyte level.

[Piran]

The electrolyte level is fine and has been since I noticed the bubbling. However, when I last topped them up a couple of months ago unfortunately some of the plates were very close to being exposed or exposed slightly as I had forgotten to do it for a few months.  It is also possible the solar controller has been overcharging for a while (which I perhaps didn't notice until recently), which perhaps has damaged and not allowed them to recover...

[GUMPY]

What was the voltage whilst they were being "overcharged"

[Piran]

I need to just check as my electrician took it, but it was definitely over the normal amount

[MtB]

4 minutes ago, Loddon said:

What was the voltage whilst they were being "overcharged"

 

I too have been wondering what the OP means by "overcharging", and what device (make and model) did the suspected overcharging,

 

Overcharging is an obsolete concept, associated with old fashioned, unregulated, dumb transformer chargers.

[GUMPY]

8 minutes ago, MtB said:

 

I too have been wondering what the OP means by "overcharging", and what device (make and model) did the suspected overcharging,

 

Overcharging is an obsolete concept, associated with old fashioned, unregulated, dumb transformer chargers.

Or modern chargers that have the voltage set too high😯

Still they are Trojans they may benefit from an equalisation charge, up to 16.2v according to the blurb I just read.

https://www.trojanbattery.com/tech-support/battery-maintenance/

 

[ditchcrawler]

4 minutes ago, Loddon said:

Or modern chargers that have the voltage set too high😯

 

 

Or go wrong

[Tony Brooks]

1 hour ago, MtB said:

 

I too have been wondering what the OP means by "overcharging", and what device (make and model) did the suspected overcharging,

 

Overcharging is an obsolete concept, associated with old fashioned, unregulated, dumb transformer chargers.

 

That is why I asked him in my reply (post2) and await some kind of answer.

 

 

2 hours ago, Piran said:

The electrolyte level is fine and has been since I noticed the bubbling. However, when I last topped them up a couple of months ago unfortunately some of the plates were very close to being exposed or exposed slightly as I had forgotten to do it for a few months.  It is also possible the solar controller has been overcharging for a while (which I perhaps didn't notice until recently), which perhaps has damaged and not allowed them to recover...

 

I very much doubt the level was anywhere near the plates. Most people think the separators are plates and even if a few mm of the separators above the electrolyte is unlikely to cause any damage at all.

 

[MtB]

1 hour ago, Tony Brooks said:

That is why I asked him in my reply (post2) and await some kind of answer.

 

 

Indeed. The OP seems to me to be putting the cart before the horse, or his "electrician" is. The batt bank is behaving oddly so it has been declared it is "overcharging" with no evidence put forward other than the batts are gassing lightly (as I read it). And they still are even though the bank voltage is 'down to' 12.6. Down from what voltage when the electrician gave his diagnosis, we all wonder?

 

This continued gassing suggests to me that they are actually, still being charged, assuming all four are gassing not just one. But we just don't know. 

 

 

Edited October 20, 2021 by MtB
For clarity

[Tony Brooks]

I think Trojan are lead antinomy so will gas at lower voltages and more readily than the far more common lead calcium so there might have been nothing wrong at all.

[cuthound]

2 hours ago, Tony Brooks said:

 

That is why I asked him in my reply (post2) and await some kind of answer.

 

 

 

I very much doubt the level was anywhere near the plates. Most people think the separators are plates and even if a few mm of the separators above the electrolyte is unlikely to cause any damage at all.

 

 

True, also even if the top of the plates are exposed by a couple of mm no damage will result as the active material is enclosed in a grid which is surrounded by a solid lead frame.

 

Damage occurs when when the electrolyte level exposes the grid containing the active material.

 

If the OP separates the Trojans and monitors the voltage of each over a few days, one will drop faster than the others if it has a short.

Edited October 20, 2021 by cuthound
To add the last paragraph