cooked battery

[bernardgreen]

Attempts to recover a 12 volts 7 Ah sealed lead acid battery were going well. It had been deeply dis-charged to about 6 volts but had seemed to recover after several days of tender loving care with a terminal voltage of about 13 volts

This evening it was taking about 20 mA on from a constant voltage recharger at 13.8 volts and had been for over a day.

Then in the space of a few minutes it become very hot and the sides were swelling out.



As it was taking less than 50 mA at the ime I assume one of the cells has gone short ciruit and discharged itself.

Motto. Never leave a suspect lead acid battery un-attended while it is be re-charged / recovered.

 

[ericmark]

I have an 88 Ah in garage now you are worrying me. In my case constent current not voltage.

Not really up with VRLA.

 

[ban-all-sheds]

Attempts to recover a 12 volts 7 Ah sealed lead acid battery were going well. It had been deeply dis-charged to about 6 volts but had seemed to recover after several days of tender loving care with a terminal voltage of about 13 volts

Did you expect, or have reasonable grounds to hope, that it could ever be brought back to a useful level of performance, not only taking a reasonable charge, but holding it for a useful amount of time?

 

[bernardgreen]

I have an 88 Ah in garage now you are worrying me. In my case constent current not voltage.

I wouldn't worry, if the battery has not been abused and the charging is as per the manufacturer's information then all should be OK

That said I am keeping a close eye on the other batteries to be used for lighting at the village Christmas Fayre

Did you expect, or have reasonable grounds to hope, that it could ever be brought back to a useful level of performance, not only taking a reasonable charge, but holding it for a useful amount of time?

Short answer is No,

Long answer is that I had hoped it could be recovered as it had, after a short period of tender loving care, provided two amp hours of supply ( 250mA for 8 hours ).

Sitting outside and covered in frost it is showing 11.5 V but this drops to 3.5 V when pulling 100 mA so it is a total loss.

 

[HERTS P&D]

Happy 70th Bernard.

Andy

 

[bernardgreen]

Happy 70th Bernard.

That should have been changed, it is a year old. ( or is it two, can't remember )

 

[ericmark]

Happy 72 then.

I have debated if worth charging battery that I have, it was given to me to start with, it was used with old caravan and with no motor mover it was really like having a big capacitor it just smoothed the 12 volt supply, now we have motor mover so need a good battery, the old 88 Ah has been used as an emergency battery to get the caravan into the drive, but will not hold its charge, so until tomorrow keeping on charge so any problem and I have a spare.

However once caravan has been parked tomorrow likely 4 months before wanted again, putting the new 75 Ah battery on charge for 4 months at 0.1 amp is reasonable, but putting the old 88 Ah on charge for 4 months at 0.8 amp when at the end it may fail anyway does not seem worth it, yet to buy new costs £80 so is it worth alternating charger between two batteries or simply to get rid of old battery?

The 7 Ah you have it seems they don't last long, theroy a VRLA should have a long life, and the large ones on the mobility scooter have lasted around 15 years and still going in spite of being allowed to completly discharge once or twice, but the 7 Ah on the stair lift seem to be doing well to last 2 years. And it seems the less the lift is used the quicker they fail.

 

[bernardgreen]

The 7 Ah you have it seems they don't last long, theroy a VRLA should have a long life,

The other batteries have given good service and are still in good condition. This failure was due to the battery being left connected to an incandesent lamp for several days by the (ex) friend I lent it to for lighting an Emergency Exit Sign. He didn't disconnect it.

In fact it is powering a short strip of LED tape lighting a sign as I type. Run it down before taking it to the recycling depot