ENLOOP OVER DISCHARGED HELP PLEASE

[Sanyo.Eneloop]

I HAVE BOUGHT SANYO ENELOOP BATTERIES YESTERDAY AND I PUT THEM IN TORCH TO USE BUT I FORGOT TO SWITCH OFF THE BULB AND I FOUND THAT BATTERIES ARE COMPLETELY DISCHARGED THEIR VOLTAGE IS .20v THAT TIME, IS THEIR ANY DAMAGE DONE TO THE BATTRIES??


PLEASE HELP GUYS

 

[SilverFox]

Re: ENLOOP DISCHARGED COMPLETELY

Hello Sanyo.Eneloop,

Welcome to CPF.

Over discharge is not the best thing to do to NiMh cells, but sometimes they will recover with minimal loss.

After sitting a few minutes, check the voltage again. You may find that it has increased to over 1 volt. If that happens, charge normally.

If the voltage does not increase, you may have to fiddle a little to get a charger to recognize it and start the charging process. If the charger does not recognize the cell, you may have to recycle it, unless you have some advanced charging equipment available.

You can throw it in the charger and see what happens. There are no additional safety issues involved with trying to recharge a cell that has been over discharged, but there may be some additional heat involved, so I would stick to the lower charge rate that charges the cell in 2 hours rather than going for a 1 hour charge.

Tom

 

[Sanyo.Eneloop]

Re: ENLOOP DISCHARGED COMPLETELY

thanx a million for your prompt reply, when they were completely dead their voltage was .20V and after 5-15 mins it exceeded to .90V but it wont reached over 1 volt


one more problem
when charging through Sony BC-CS2A the charger should cut off after 5 hours because cells are rated 2000mAH and charging current is 400mA so 400mAx5=2000ma and charger wont cut off at 5 hours i have to switch it off to save the poor battried

after charging cell is showing 1.40V constant

what u say guys cells are killed ?????

 

[SilverFox]

Re: ENLOOP DISCHARGED COMPLETELY

Hello Sanyo.Eneloop,

You actually have to put more back in than you took out. Charging NiMh cells is not totally efficient.

The amount you put back in varies with the charging rate. At 400 mA, I would look for around a total charge of 120%, or a little bit more. This means that your charger should complete the charge in about 6 hours with totally empty cells. If the charger is still charging after 7 hours, I would suggest manually stopping the charge.

You should set a timer when you start the charge and keep an eye on the charging process. When the cells start to warm up, they are near the end of the charge. If the charger doesn't shut off, you may have to manually terminate the charge.

With cells that have been overstressed, it may take a couple of charge/discharge cycles to get them back to normal performance.

Tom

 

[Sanyo.Eneloop]

Re: ENLOOP DISCHARGED COMPLETELY HELP PLEASE

thanx Tom, i never know that charger stops at 120% after 5hours and 20 min i feel batteries little warm but i was scared that if i don't stop now batteries will fried badly, i think i should wait for at least 6hours next time.

 

[Sanyo.Eneloop]

my charger is not stopping the charge at 6 hours+ why this is happening???


i use Sony BC-CS2A

 

[SilverFox]

Hello Sanyo.Eneloop,

I am not sure what termination method that charger uses, but I am not a fan of its charge rate. In order to produce a strong end of charge signal you need to charge the cells in 1 - 2 hours. Many chargers use other back up methods, but sometimes these don't work properly either.

On top of that, your cells may have suffered a little from the deep discharge and may take a few charge/discharge cycles to get back in some kind of normal shape.

In general, when the cells warm up they are nearly fully charged. You can leave them in the charger for a while longer, but if the charger doesn't stop on its own, you will have to terminate the charge yourself. If you know how long it normally takes to charge your cells, you can set a timer to remind you to check on them. If they are still charging away when you think they should be done, the charger has missed the end of charge signal.

Tom

 

[Sanyo.Eneloop]

finally charger stopped after 6.5 hours!!!!