Leisure battery questions

[ellal]

Hope this is the correct forum, if not please move.

Have inherited a 120Ah leisure battery which hasn't been used at all for at least 18 months.
It is holding a constant 12v, but I want to do a good charge before using it in conjunction with a solar panel/inverter for small auxiliary power.

The questions I have are:

At 12v does that indicate a useable or dead battery?

I have tried charging with the 8A basic battery charger I have, but on either normal or fast cycles nothing changes.
The charger is rated at only 80Ah, so is it possible to be an underrated charger problem?

Not sure if I want to throw money at what might be a dead battery rather than getting a new one, but if it can be resurrected cheaply that would be better than adding to the scrap pile!

Any diagnostic advice appreciated.

 

[Mottie]

If a battery has been flat for some time especially over the winter, it’s usually unrecoverable.

 

[ellal]

If a battery has been flat for some time especially over the winter, it’s usually unrecoverable.

Even a leisure one?

I've googled about smart chargers when the voltage goes that low.
Are they worth a punt?

 

[Jackrae]

Your charger pobably only puts out about 4 amps so if the battery is fairly low then it'll take a couple of days for it to charge.
If you measured 12v on the battery BEFORE you connected the charger then it's probably still good.
A reasonably priced smart charger will have a relatively low output currect and could take at least a week or two before it cuts back
You need to advise on battery type lead-acid, gel, etc Make and model number would be useful

 

[ellal]

The battery before connecting the charger was on 12v
(the odd flicker down to 11.9v or up to 12.1v but that's probably the meter)

Guess I'll be more patient and run the charger for much longer.

Which means a further question regarding charging.

Given the time of the year, is it better/quicker to charge it somewhere warmer than an unheated garden workshop?

 

[Mottie]

Don’t stand the battery on a cold cement floor - that sucks the life out of them. Put it on a bench or a piece of cardboard. I 'reconditioned' my bike battery a few weeks ago and I have a decent C-Tek charger/conditioner that does bike, cars, AGM etc. It worked for a while but soon relapsed so I bought a new battery last week. Might be worth your while buying one if you will get some use out of it but if it’s just the one battery and it won’t take a charge after a day or two, just replace it. You want at least 12.6v in it when charged, preferably more.

 

[ellal]

Don’t stand the battery on a cold cement floor - that sucks the life out of them. Put it on a bench or a piece of cardboard.

That one I did know.
It was the ambient temperature I was wondering about.

Funnily enough I've had to replace the battery recently on one of our cars and that had a wedge of newspaper underneath it in the metal battery tray.

Same principle?

 

[Mottie]

Sometimes with a battery that’s stood for a while a couple of charge/discharge cycles can do the trick.

 

[Rodders53]

12.0 V for a lead acid leisure battery is about 25% state of charge at 10 Celsius. So although it may now have a reduced capacity it should be rechargeable. Any charger when pushing current into a battery would need to be well above 12.7 - 13 V... If you measure no voltage increase then the charger is kaput, blown a fuse or in a protection mode.

Simple 'dumb' chargers may be constant current and then it's easy to overcharge and ruin a battery. You need to read the manual.

A smart charger - cheap enough from Aldi or Lidl when they have them in the middle aisles - would be ideal. CTek if you can afford one. Depending on the exact LA chemistry the charging voltage regime is different. Ask friends, family, colleagues and neighbours if they have another charger you could try/borrow for a while?

Concrete floor is an urban myth... and to do with days before plastics casings for batteries. From my go to batteryfaq source:

In the early 1900s, battery cases were made of porous materials such as tar-lined wood boxes, so storing batteries on concrete floor would accelerate their natural self-discharge due to external leakage. Modern battery cases are made of polypropylene or hard rubber. These cases are better sealed and insulated, so external leakage-causing discharge is no longer a problem storing batteries on concrete floors. That is provided the top of the battery is clean and free from wet or dried electrolyte and are same temperature as the floor.

 

[ericmark]

Leisure batteries were designed as a hybrid between the traction battery and the vehicle starting battery, they will not deliver as many amps as a vehicle battery, but do stand deep cycling better, but not as good as a traction battery. All being lead acid of course.

The the development of the absorbed glass mat (AGM) or valve regulated lead acid (VRLA) has seen the leisure battery will flooded cells being less used, but they have also generated the need for the smart charger to recharge these batteries without damage.

In the main the smart charger is a stage charger, often current controlled, the pair I got from Lidi have 5 rates, 3.8, 3, 0.8, 0.1 and zero amps, the big thing is they can be left on the battery 24/7, as they auto switch down or off as required. They will switch off when battery voltage reaches 14.4 volt, and on again at 12.8 volt, so the battery sits at 12.8 most of the time, and as it self discharges, the charger will switch on for a short time until 14.4 volt is reached, then back off again. I have used an energy monitor to see this happening.

If a battery has been flat for some time especially over the winter, it’s usually unrecoverable.

That was my thought, until the advent of the smart charger, the sulphur in the acid is deposited on the plate, and slowly becomes harder and harder, it does not seem to matter how much charge you try putting in, the sulphur once hard says on the plates, however it seems if left on charge for an extended time, that can return the sulphur to the acid, we can be looking at three weeks, leaving a battery on charge for three weeks would have before the smart charger wrecked the battery anyway, and if a regulator is used, 13.8 volt is not enough to equalise the cells, it is the pulses delivered by the smart charger which does the trick.

The narrow boat people had worked this out long ago, the batteries would never get fully recharged using the engine, 8 hours cruising is not enough, but if once a month they can connect to shore power for 48 hours, the batteries would last a lot longer.

The problem with the Lidi charger is under 8 volt it assumes the battery is a 6 volt one, so will not recharge it. But I have not used my car for months, and the battery has dropped to 9 volt, but the Lidi charger has brought it back up without a problem, but does need to be left on charge for days, once the charger shows fully charged, it is still charging at 0.1 amp, and the voltage will slowly creep up, 40 Ah battery now showing 12.9 volt, I will take it off charge when it shows 13.8 volt at the 0.1 amp rate. It took a long time to self discharge, so one must expect it to take a long time to recharge.

 

[flameport]

Have inherited a 120Ah leisure battery which hasn't been used at all for at least 18 months.

It's scrap.
Don't waste any time or money on it.

 

[Old Salt]

My leisure battery used to get fully discharged on a regular basis but always rallied round. In use for 5 years and still going strong when motorhome was sold.

Its worth persevering with until you are convinced its dead.

 

[ericmark]

If a battery gets a shorted cell then it's dead, and with a battery showing less than 11 volt it may have a shorted cell, and even a 3 amp charger can cause it to buckle plates and emit sulphur dioxide bad egg smell, plus hydrogen gas which will burn rapid with a blue flame.

But I have recharged many a lead acid battery left discharged for an extended time using a smart charger.

 

[DetlefSchmitz]

... and emit sulphur dioxide bad egg smell...

My recollection from school is that a 'bad eggs' smell is hydrogen sulphide, and that sulphur dioxide has a very sharp unpleasant smell. Of course chemistry might have all changed these days.

 

[ericmark]

Yes sorry my error.