Dead NIMH Cells

[Crash]

Havng not used my cells for quite a while (2-3 years!) I have noticed that I am struggling to get them to accept a full charge. Each of my packs appear to have 2 cells with very low voltage and are presumingly dead.

Now here comes the silly question.........can they be revived/saved??

[Chequered Flag Racing]

Originally Posted by Crash

Havng not used my cells for quite a while (2-3 years!) I have noticed that I am struggling to get them to accept a full charge. Each of my packs appear to have 2 cells with very low voltage and are presumingly dead.

Now here comes the silly question.........can they be revived/saved??

can you charge to 2 cells as singles?

it maybe that the other 4 are fully charged

do the other 4 cells get wrm to hot when charging the pack?

if they do you will need to discharge each cell in the pack on a Novak Smart Tray or similar to get all 6 voltages equal

[stoff]

Sometimes they can be revived but you will need a charger that can charge a single cell. Charge at quite a hight amperage to see if you can bring it back to life.

I had some EnerG 4600s that were sat for a while. They were stripped to single cells and individually charged. I think out of 20 cells only 2 were dead.

[Crash]

These are intellect 4200's.
Just checked my charger and it will only go down to 4 cells but I'm going to stop by a local track tonight to see some old mates and I'll have a look what their chargers can do. Have even considered connecting the dead cells directly to a variable power supply and 'force' some energy into them.

[MattW]

With Intelect 4200's I would advise extreme caution - as some batches of these were the most volatile cells that we saw.

[tonymon]

ye i had one blow up the other week, very load bang right next to me! forced me to go lipo too! so yes volatile cells

[Matt Airbrushing]

If you have more than two packs then it might be worth swapping the cells around to make up two good packs from three.

I had to do this with my old NIMH cells and I managed to make three good packs from five with a couple of good cells left over.

Trying to "recover" the damaged cells will be difficult anyway.

[SlowOne]

Use the cells with voltage to make complete packs. Don't try anything on the ones that have no voltage. IBs are, as stated, unstable. Even if you get them to so something using some sort of hoodoo voodoo, they'll be poor, and will drag down the good ones in the pack. As a rule of thumb, if the cell has less than 0.9v in it, and has sat for that length of time, it's use should be confined to paperweights or recycling fodder. HTH

[teamxray]

try leaving the pack on a trickle charge will also help it back to life then try a quick charge into the pack

[Col]

I suggest moving into the 21st century and scrap those old explosive's.
A good quality lipo and charger can be had for £60 these days

[Crash]

Cheers guys your input is really helpfull, and yes I do admit to avoiding the transition into the 21st century and lipo's haha

just borrowed a pulsar 3 charger and the suspect cells appear to be accepting charge when I charge them individually. Planning to charge each cell individually then discharge the whole pack down to 5.4v. Try this a couple times then use the cycle function on the charger and see what happens.

Here's hoping it works

[SlowOne]

(Puts on tin helmet and moves to next county... )

[Chequered Flag Racing]

Originally Posted by SlowOne

(Puts on tin helmet and moves to next county... )

room for one more

[mikeyscott]

Are you needing NIMH cells for Sunday? if so PM SteveB

[bodgit]

Def put a pair of safety specs on. When they go its not worth being blinded.

[Crash]

All good so far, no loss of sight or limbs as yet. I checked the problematic batch numbers for the IB4200WC cells before i started messing and mine appear to be completely different.

Voltage has returned/stabalised in each cell but i totally agree with you guys that i'm pushing my luck here, and could possibly be classed as a stupid idea.

thanks for the continued help/advice

[Big G]

Originally Posted by MattW

With Intelect 4200's I would advise extreme caution - as some batches of these were the most volatile cells that we saw.

+1 I had a pack melt things in the car

enerG 4600's never had a problem with