Who is Right?

I have recently resurrected a 6v Lantern battery. I gave it short bursts of 12v during the charging process which some schools of thought suggest and it appears to have done the trick What are members thoughts and/or experiences in a) using this method OR b) suggest an alternative method?

Method C?

Often these batteries suffer from dry electrolytes. They are not really sealed in that if overcharged even slightly the gases escape through the relief valve. It’s usually possible to prise the top off and removing the rubber caps, which are the relief valves, to squirt a little distilled water to revive the cells. Sealed lead acid batteries need a charger that regulates the voltage applied to each cell which from my fading memory is something like 2.35 volts per cell.

Bert

Blows off the whiskers that grow between the plates

It's a trick that works up to a point. How well, or not, depends on the battery technology inside the case and why the individual battery went flat. Left in a cupboard for 5 years is different from flattened in a single session.

Lantern batteries are usually Primary Cells, i.e. not rechargeable. Although the chemistry of most primary cells is the wrong way round, they do allow some recharging. Side effect, not a deliberate feature. Primary cells also recover somewhat after a rest, and when warmed up. The battery isn't really restored and it's certainly not reliable. (Don't use them in your pacemaker!)

Some secondary Cells degrade by growing crystal whiskers between the plates. It's possible to zap the whiskers by over volting or shorting the battery, but again with only partial success, if at all. They're stretched rather than fixed.

Two ways of looking at these methods:

1. Worth trying as a way of extending the life of a battery you already own and don't expect much.
2. Dishonest if a dud battery is temporarily rejuvenated for sale to someone else.

Dave

Edited By SillyOldDuffer on 14/11/2020 21:35:29

Get a CTEK charger that does the job.  
 

Lead/acid cells are secondary cells and leaving them discharged allows the plates to become sulphated.

Edited By not done it yet on 14/11/2020 21:39:08

Now I am even more curious. We have replies and suggestions so far based presumably on guess work. Pete's reply which he has now deleted summed up what I was thinking. Why delete it Peter?

I made a guess at method C because the OP's question being unanswerable.

Ian P

Ian P,

That means that you must have read my original reply before I deleted it - short window of literally a few seconds.

I deleted my reply because I realised that I had made a silly mistake. What happened was that I was commenting that the OP did not state the battery technology, and after entering my post, I realised that the (secondary?) thread title did indeed mention lead-acid, hence I was wrong. That's all it was.

I did include some information re K.C. Johnson's experiments with NiCd cells back in 1975 along with a brief summary of his conclusions, but that was just as a historical comment.

Peter G. Shaw

As we are taking this seriously.

Lead acid batteries also suffer from lead paste that drops out of the plate matrix. When there's enough lead slit built up the plates start to short out.

The battery capacity drops till suddenly the charge disappears over night. You could recover some life if all the acid is drained out and then put back in twice leaving the grey sludge behind, but only till pay day.

It's a bit 70's along with 'Batt Aids' tablets, No6 tipped and the smell of half burned petrol on the way to work.

We have no idea of the real situation with the battery. Old and worn out, new and left discharged, continually run to almost complete discharge, or what? The CTEK chargers, while not cheap do a good job, if possible.

During the lockdown, the battery in my wife’s car ‘failed’ - in that it most certainly needed charging (dead, as far as starting was concerned). Charging ‘rejuvenated’ it to the point of usable (started the car OK) but the time between switch off and the electrics going into ‘saving mode’ where the radio, etc were disabled to conserve the battery was measured in only a few (around five or less) minutes.

I then ‘borrowed’ a CTEK charger and put the battery through the ‘reconditioning cycle’. The battery is now back to at least the usual ~30 minutes, after stopping the engine, before the stand-by mode is activated.

Edited By not done it yet on 15/11/2020 12:13:18

Well spotted - I missed that information, and it makes all the difference!

Almost invisible thread sub-titles should be listed as a software flaw in Lee's 'Archiac Forum' thread!

Dave

I too missed that.

I read through the whole post again before I sent my last post looking to see if the OP had stated the battery technology. I never saw the sub title.

I have fallen into the same trap before, so yes it is another item on Lee's list. Might be easier to deal with as its something to remove completely, I don't really see the purpose of a sub title.

Ian

If the battery required 'restoration' because it was sulphated, which seems likely, you may have got lucky. The sulphation often can be broken down by charging at an elevated voltage, but it's important to limit the current, to avoid damage. Really, a constant-current charger should be used for this trick, and 'sealed' lead-acid cells should in any case be charged at no more than the recommended current because of their limited venting ability. If over-charged, the electrolyte breaks down, the cell 'gasses' through the safety vent and electrolyte is lost, reducing the capacity of the cell. So, to recover a battery properly (if it can be recovered - and it will likely be only a partial recovery), a fancy charger is required, or you need to monitor and control charging current and battery voltage fairly carefully.

Another toe of snail alchemy trick. Many years ago, the Miller charging system on my Velocette Venom gave up the ghost. My lowly apprentice wages didn't allow an immediate repair/replacement and as the battery only did the lights, (Mag Ignition) my twenty mile round trip to work only needed side lights and yes, depth of winter, a bit of a necessity. Charge used to last for one days usage so when someone suggested emptying battery and flushing out with warm washing soda it was nowt to loose. First couple of flushings gave effervescent reaction (acid neutralization by alkali) but after that, a couple more swillouts before clean water finals and finally replacing electrolyte resulted in full charge lasting three days. Charging system was replaced later thanks to the Prince of darkness but the forgoing was a welcome stopgap.

Regards Ian.

FIL had a 6 volt tractor battery go bad. I found a place to rebuild it. Took it in and asked if I could watch while They "fixed" it. First They scrubbed the outside and dried it off. Then stuck a pair of leads into adjacent cells and check something. Said it was good, then put a mold around the terminals and hit them with a torch and made them look new again. Put about 5 minutes of charge into it and pronounced it rebuilt. It lasted a couple of more years, for $20.