What happens if you overfill a battery cell?

[Barroca Grande 2]

Hi all

 

I finally girded my loins and undid the caps and filled all the cells on my 'new' lead acid batteries (Banner A115)

 

When my previous lovely maintenance free agm? batteries 'blew up' back in July 2014 I got three lead acid batteries as replacements. In October 2014 shortly before putting the boat to bed for the winter I added two more of the same.

 

So it was probably well overdue that I did actually top them up. Now I am pretty sure the four batteries in the battery box have NOT been overfilled as I could see that the level came to the little blue notch thingy hanging down in the hole (which I have assumed is the level indicator?).

 

But the single battery on the swim is a different matter it is well nigh impossible to fill them so absolutely impossible to know if I have overfilled them. I am reasonably confident that the last four of the six cells I attacked haven't been overfilled however the very first one I attempted looks decidedly dodgy and the next one in I might have overfilled in my exuberance (ie so much water went into the first one). I say it looks dodgy from the shadows created by having a lantern placed beside the battery.

 

To reach this 'on the swim' battery I had to wriggle under and over various obstacles and then hover in the yoga snake position while one hand held a tiny funnel and the other poured the (distilled) water in using a china milk jug. All the while trying not to poke my eyes out on the battery clamp pole. (I did put a lump of blue tac over it just in case).

 

My question is this - what happens if I have overfilled the cell when I next run the engine?

 

I would also mention that about 4 litres in total of distilled water was put into the 5 batteries.

 

Plus is it possible to buy replacement cell plugs as two of them have been damaged in trying to undo them. I have tried to google for them but don't know what they are called and they are not appearing in my results list.

 

Please be kind as this is the first time I have had anything to do with lead acid batteries - I am not impressed so far with them but that might have been because they were running dry?

 

Thanks

Kath

[Nickhlx]

Buy replacement plugs ?

 

I'd pop down to any battery shop that replaces, or a dump, and get one off an old one.

 

The right-angled rubber fillers that go on an old bottle are so shaped that you can drop the filler into a cell and when the bubbles stop, the level is above 1/4" above the plates

 

Nick

[Barroca Grande 2]

the right angled rubber fillers? Me no unnerstand.

 

I have today bought a set of straws and a baby bottle with an integral straw for the next time I attempt this task. The straws are so you can put one into the battery cell, put your finger over the end and lift out gently to see how far up the straw the liquid went (all without spillage hopefully). The baby bottle for filling

Edited March 5, 2015 by Barroca Grande 2

[Alan de Enfield]

Have you amended your charging voltages when you changed from AGM to Lead Acid ?

With AGM the float charge should be between 2.25 and 2.30V/cell (summer temperatures may require lower voltages). Whilst flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell),

[Barroca Grande 2]

I think everything was changed over - I had a run of help on this forum back in July/august to help with this. I only use the engine for charging (and the solar panels but I am unsure of them at the moment) I will be getting the solar panels checked later this month.

[Keeping Up]

the right angled rubber fillers? Me no unnerstand.

 

 

One of these perhaps. A bit expensive but they do the job

 

[Barroca Grande 2]

Thanks for that (my baby bottle will do the same thing I hope) (Well it wont automatically stop) Clever design. Hmmm

 

However my real question is what is going to happen when I next run the engine with the possibly overfilled cell?

Edited March 5, 2015 by Barroca Grande 2

[Arthur Brown]

http://www.ebay.co.uk/itm/Vintage-Lucas-Battery-Filler-Glass-Bottle-Cars-Motorcycles-Scooters-etc-/371270941308

 

will top up to the correct level.

 

Nothing significant will happen to the overfilled cells if the battery is generally well charged.

Edited March 5, 2015 by Arthur Brown

[Barroca Grande 2]

Oh thank you thank you for that. Splendid I can go to sleep tonight.

[forsberg]

If you get one like this

http://www.rimmerbros.co.uk/Item--i-CONS2235

You can remove the floaters and use it for both filling and checking level

[Richard10002]

Alpha Batteries told me off for overfilling my batteries. They said the electrolyte was diluted, so the specific gravity would be too low.

 

They kept them for a few days to refill them with the correct mix of water and acid, and they seemed fine for a while after I got them back. I haven't had to top them up in the 2 years I've had them, but they are now shot and are to be replaced by 4 Trojan T105s.

 

There was no indicator in the batteries, (Varta Hobby), but they said that the level should be about a centimetre above the top of the plates.

[nicknorman]

Overfilling a bit won't matter. Drastic overfilling might cause acid to leak out of the vent during charging, but I think it would have to be virtually full to the top for that to happen. Obviously the acid will be diluted a bit too much, which might impact on capacity a bit, but I we time the excess water will be "boiled off" allowing the level to return to normal, eventually. From the sound of the access difficulties, I think it would be worth your while getting an automatic battery filler such as was linked to by Keeping Up.

Edited March 5, 2015 by nicknorman

[bottle]

or

 

Go the whole way and get a fully automatic level and filling system. (don't ask the price because if you do you cannot afford it )

 

Just one example: http://www.globalbatteryshop.com/stealth-float-valve-kits-371-p.asp

[LEO]

 

One of these perhaps. A bit expensive but they do the job

 

Seconded - it does the job!

[David Schweizer]

I use one of these with a length of polythene pipe attached to the nozzle.

 

I had boxes full of them of them after my operation, and they have to be thrown away once they are used. so I kept some in case they came in useful !!

[alan_fincher]

 

One of these perhaps. A bit expensive but they do the job

 

 

Strange - I thought those were on offer at Midland Chandlers at the moment, but the price there doesn't look like they are. Worth asking if anyone is buying one.

 

 

[casper ghost]

The liquid in my batteries is about level with the top of the plates, so do I need to add some?

Casp'

[bottle]

The plates should be covered at all times but there must be an air space above.

[Arthur Brown]

The plates should be just covered at all times so 1/8 - 1/4 inch would be typical, leave a gas space too. Charge the batteries after any significant top up -it mixes the acid and the water.

[blackrose]

Seconded - it does the job!

I use one as well. It makes an unpleasant job a lot easier. Unlike some other methods it means you don't even have to look to check the level.

Edited March 5, 2015 by blackrose

[Nightwatch]

Salad cream bottle with the 'stop the flow' thingy in the lid.

[cuthound]

As others have said, top up so that the level is a quarter of an inch (4-5 mm) above the plates and then charge to mix the electrolyte.

 

If you overfill, the surplus electrolyte will be ejected as a mist by the hydrogen given off when the battery is charged. Over time this acid mist will cause corrosion of the terminals and provide a lower resistance path across the top of the battery, causing increased self discharge.

 

Best to use a hydrometer, turkey baster, syringe with tube attached to remove the surplus electrolyte. If the top of the battery has been subjected to an acidvmist, then remove it and clean the top and terminals.

 

Best to use a filling device which automatically shuts off at the correct level unless you can clearly see the electrolyte levels. It will pay for itself in reduced aggravation

[smileypete]

The liquid in my batteries is about level with the top of the plates, so do I need to add some?

Casp'

 

Yeah but hard to say exactly how as it can depend on the batt and it's condition.

 

When new the batt should be delivered topped up to the correct level, in an ideal world this would be recorded somewhere for future reference.

 

cheers, Pete.

~smpt~

[blackrose]

Salad cream bottle with the 'stop the flow' thingy in the lid.

You will still have to check you're not under or over-chilling with that method.

 

For inaccessible batteries that you can reach but are difficult to see inside, the yellow Duralite bottles that stop the flow automatically once the level is correct are the simplest solution.

Edited March 6, 2015 by blackrose

[bottle]

Only if you can get to the battery top and the bottle upright.