Battery charging - fizzing noises

[DrDonnyBrago]

I was just charging up a car battery for a neighbour (a maintenance free, 70Ah battery) - I stuck it on charge using a charger I bought from Lidl, identical to the one that this robbing twat is selling for twice what he would have paid for it:

https://www.ebay.co.uk/itm/Ultimate-Speed-Smart-Car-Battery-Charger-/270975759656?pt=LH_DefaultDomain_3&hash=item3f1769f528#ht_499wt_1416

In car battery mode, unless it is really flat then it uses 14.4v and 3.8A to charge and it does so until the battery is full at which point it goes into maintenance mode.


ANYWAY, I had the battery on charge for a few hours (about 6/7) and went and had a look to see why it was taking so long, there is a faint fizzing noise coming from the battery. I have heard of batteries producing gases when charging but I thought that was more a thing to do with old style unsealed batteries. This is a sealed battery, surely if it is producing gas then it wont vent and the thing will blow up.

Is it normal for sealed batteries to fizz during charging, I haven't noticed it on other batteries and it isn't especially loud. If you put your ear close to it you can hear a definite fizz. I have now unplugged it.


So - is it normal and I can safely resume charging or should I tell the neighbour that the fizzing is probably me overcharging the few remaining functioning cells and that she needs to buy a new battery as this is both dead and about to explode.


Cheers

[andym]

I always thought it was normal for them to fizz while charging, sealed or not

[DrDonnyBrago]

Possibly, I thought maybe the chemistry was slightly different so that the electrolyte doesn't bubble away and need topping up (i.e. they minimise/eliminate fizzing).

I cannot find the vent on this battery and I haven't heard any of the other batteries I have charged fizzing.

[Taught2BCauti...]

Nothing to worry about - all lead-acid batteries give off hydrogen gas and water vapour as they charge, even when they are in service and being charged by the alternator.

There will be no significant build-up of pressure, because the gas comes from the electrolyte, and the level will drop accordingly and rise again as the gasses condense.

Sealed batteries have just the right amount of electrolyte, with just the right amount of air so as not to cause problems with pressure.
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[haroman666]

Last time I heard fizzing from a battery, i'd fried it.

But I was being a daft prick and I put a car charger on a bike battery...

But outside of my little bubble of stupidity, when you charge a battery, it's relatively normal to hear gas/fizzing.

But it still might be worth checking it with a multi-meter
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The mistresses: 2000 Honda CBR600f, 2000 Honda VTR1000

[coggie]

[Fizzer Thou]

When a car or bike battery charges the electrolyte causes the internal plates to give off a gas.This is what you can hear.

Once the battery is fully charged,the internal resistance increases and the battery charge rate should decrease,so decreasing the current flow.

But if one or more internal plates are damaged,they will continue to cause current to flow at a higher rate.
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