Battery prob's
 

Awright chaps...wonder if anyone can tell me what is going on with my cells.....

I've got 4 packs of 3300's and i have had them stored for a few months. Before I did. Rightly or wrongly (cos i wasnt sure) i discharged them and then put them on a an orion discharge board.

I have got them out with the intention cycling them a few times but now the packs when charging get very hot and start to make a low sort of pulsing sound after a while of charging.

I charged them at 5 amps and this is happening and also charging at 4 amps. The packs are a few years old now cos I bought them 2nd hand when i got them.

Can you tell me what is happening and importantly ....are they screwed? I charged a packs tonight and it started happening 3000 mah according to the charger...I took it off charge straight away. I ran it in the car and it seemed fine....

Thanks ahead chaps

After discharging you should of put a bit of charge in them, just keep trying charging them at a very low rate and equalising again building up the charge rate, they should come back being 3300's

thanks josh....what would you recommend as a low charge rate? Also, if this pulsing noise starts should I take them off charge??

Id say start at 1A and go up 1A each cycle, if the cells start making sounds id take it off and run lol, just make sure the vents havent sealed around the positive button.

I agree, charge at 1A then do a gentle discharge, they should be good to go at 4 amps then

cheers dude

my thinking exactly on the noise front!!!

The cells are just venting, this is ok, its when the vent is blocked that they explode:thumbsup:

I think id still find it :o rather than :thumbsup: lol, Although id prefer this than a small grenade going off.

where is the vent? I'd like to check if it is blocked?

cheers again

Its the ring around the positive button on the cell, usually black, sometimes red. If its blocked its just sealed around the edges and cant let the gas escape thus building up pressure and.... BOOM. But very doubtful of GP cells :D

ok, how can that happen if it has? a problem in manafacture. they are a few years old and never done this before so i'm thinking they are not blocked...

is this some issue with them being stored with no charge which is causing the venting?

I'm gonna try charging them at 1 amp tonight.....

As cells self discharge due to internal resistance and internal resistance increases with time/use and that self discharge to 0V harms nimh, then I'm afraid storing with no charge is the worst thing you coulds have done.

Low rate charge cycling is your only hope BUT IT IS ESSENTIAL TO EQUALISE THEM. In fact turn the discharger off early so no cell finishes and goes dead flat before the others.

Any individual cells venting are on their way, consider binning those and re-soldering only good cells?

i'm beginning to think it is time to call a day on them?

I wouldnt just yet, they are GP3300's after all. Charge them at 1A, equalise down to 0.9V, charge at 2A, equalise again and so on building up to a 4A charge (4A max). For the first one or two charges at least use a low mV cutoff so it cuts off it you have a dud cell, with a mV cutoff of around 4mV then it should peak the cells prematurely if you have a dud cell.

HTH :thumbsup:

Throw them in the re-cycle bin! Stormforce are doing brand new BRCA legal cells for £36...

chhers for all the help chaps