Ouch! Too Hot To Hold - 2400mAh Powertech Rechargeable Metal Hydride Batteries

[mal from cessnock]

Is this an issue with other members? Gross overheating during re-charge?

I have 4 sets of 2400mAh Powertech Rechargeable Metal Hydride Batteries in my kit. I don't use them much but I top em up every couple of weeks - I use them in my Canon Speedlite, generally just for fill. I don't like to be without a set and because I'm paranoid have extra sets with me, just in case

I re-charged them all last night using two rechargers that each take four batteries. Each set takes about the same time to charge, say 30mins. After doing 2 sets of 4, I whip em out and do the second lot.

Now this observation is common and troubling - I've taken to storing them in red and blue containers for id purposes. 2 sets come out of the rechargers cold, they go in the blue, but the other 2 sets come out very hot. I decided to submit this thread last night cause the hot ones were just so hot, I could only hold them for a few seconds for fear of literally burning my hand.

I'm pretty attentive and remove them from the recharger when they are done.

I wonder why there is this difference, 8 come off the charger "cold" and 8 come off "hot".

Any ideas?

[Darey]

Following are 2 things to consider.

1/. Are the hot and cold batteries coming out of the same charger? If the hot ones are from one charger and the cold from another then the charger producing the hot batteries may be suspect. It may be pushing too much current (mAh) through the batteries.

2/. Simple physics states that an electrical current has to flow through a resistive path to create heat. Generally batteries have a low internal resistance when they are in good condition therefore they don't get hot. Maybe the hot batteries are older and are beginning to deteriorate and therefore their internal resistance id increasing. You may need to replace the hot batteries soon.

I hope the above helps as a guide.

[ameerat42]

^^Exactly what he said. I couldn't tell if you had 1 or 2 chargers, though I rather suspected two.
Now I have the same batteries, but only 4, and the charger is a Powertech MB3544.
The batteries come out warm, sometimes rather warm, but I'd never say hot.

I'd be taking it/the suspect one/batteries back to (I assume) Jaycar???
Am.
Oh! Just a thought. They're NiMH batteries. Are yo sure the chger was set to that and not NiCd? (OK, 4-get I asked.)

[mal from cessnock]

Darey, how is it going - have you stopped drinking red? I should stop drinking port.

Batteries overheat in both chargers.
This system is less than 12 mths old and has been like this since new - however, the batteires which heat up are now much worse than previously.
For future purchases of rechargeable batteries, can I take it as a rule of thumb that if they heat up, I am within my righs to return them as faulty units?
My previous system of Aldi batteries did the same (ie some would overheat whereas some would remain cold)

Thanks Darey

[ameerat42]

4-shore. I'd be running back. And I have used the Aldi batteries too. Again, with little drama for heating. (Though a couple carked it after I had lost them in a drawer for almost a year.)

[mal from cessnock]

Ta Ameerat42

[mal from cessnock]

A quick follow up on this matter fellas.

I've used my batteries and have recharged them all a couple of times since I reported some getting really really hot upon charge.

Well wouldn't it (although I'm pleased) but the tagged batteries which were over cooking on recharge have remained "cool" after the last couple of charges. Go figure!

[arthurking83]

Generally, you may get slightly hotter batteries when using those 'quick chargers'. This is a good way to kill batteries prematurely too(FWIW) sometimes you just have too, to keep up with power demands, so there's always an amount of give and take to consider.

I have various flavours of Powertech batteries myself, and all purchased about 5-6 years(maybe more!) ago. All in good condition and holding charge very well too(I have both 2400's and 2500's too, and a few 900 AAA's as well).
I have two chargers, to cover close to 20 batteries in all, and what I do is to keep a set of 8-10 in the bag for general use, but basically hardly ever use them. They could sit unused for months in some cases, and they still have enough power for most of my needs.
If they've sat for too long, I then pull them out and use them up in some power hungry device for a short while and then place them onto my slow charger.
I got a 10(AA/AAA) battery charger that basdically trickle charges them over a long period, and they never heat up at all in this charger, these batteries can sit in the trickle charger for months at a time, as the the next set to go into the bag or for any other use.
I also have a quick charger and use it sparingly.. maybe once in a year or so, ie. only when I've run out of power.

I think the trick to prolonging the life of rechargeables is to use a trickle charger. I got mine from Jaycar many moons ago, and they have all manner of newer/better devices to do the same thing now.
The one I have also has a discharge button for those pesky batteries that don't want to charge up correctly. Basically, you leave the pesky batteries in and press the red button, the charger goes through some discaharge routine and then automagically charges them again. This is apparently to keep them in top condition, and I have to say of the few that have been pesky over the past few years, this seems to work. Haven't replaced a NiMH for years now

[arthurking83]

Generally, you may get slightly hotter batteries when using those 'quick chargers'. This is a good way to kill batteries prematurely too(FWIW) sometimes you just have too, to keep up with power demands, so there's always an amount of give and take to consider.

I have various flavours of Powertech batteries myself, and all purchased about 5-6 years(maybe more!) ago. All in good condition and holding charge very well too(I have both 2400's and 2500's too, and a few 900 AAA's as well).
I have two chargers, to cover close to 20 batteries in all, and what I do is to keep a set of 8-10 in the bag for general use, but basically hardly ever use them. They could sit unused for months in some cases, and they still have enough power for most of my needs.
If they've sat for too long, I then pull them out and use them up in some power hungry device for a short while and then place them onto my slow charger.
I got a 10(AA/AAA) battery charger that basdically trickle charges them over a long period, and they never heat up at all in this charger, these batteries can sit in the trickle charger for months at a time, as the the next set to go into the bag or for any other use.
I also have a quick charger and use it sparingly.. maybe once in a year or so, ie. only when I've run out of power.

I think the trick to prolonging the life of rechargeables is to use a trickle charger. I got mine from Jaycar many moons ago, and they have all manner of newer/better devices to do the same thing now.
The one I have also has a discharge button for those pesky batteries that don't want to charge up correctly. Basically, you leave the pesky batteries in and press the red button, the charger goes through some discaharge routine and then automagically charges them again. This is apparently to keep them in top condition, and I have to say of the few that have been pesky over the past few years, this seems to work. Haven't replaced a NiMH for years now

[davenn]

yes i agree with arthurking,

Fast charging is a sure way to kill/severely shorten the life of NiCad or NiMH batteries. You said a 30min charge thats really fast!!. to be really honest, if you were bringing those batteries back to my shop for a refund and I knew you were fast charging them, I wouldnt want to know about your problem.

several considerations for you....
1) some brands may handle fast charging better than others
2) Were they an el cheapo ALDI brand ? or a well known decent brand ?
3) There may be an intermittant fault with the charger

I NEVER fast charge any of my nicad/nimh batteries, they get used in many electronic items that I own. They all get slow charged over night.

cheers
Dave

[Kym]

Fast charging is fine IF (and this is they key) you have a quality charger that has multiple peak detection methods and over temperature protection!!! eg. MA C9000 from ProTog site sponsor http://protog.com.au/maha-powerex-mh...campaign=C9000

As long as the charge rate is not more than about 1/2 C then you should not have any issues and have along life from your cells.

If they get too hot you are boiling off electrolyte - and that is what will kill cells.

If you only slow charge you may have other issues that the occasional fast charge will fix

[Pine]

It should be hot to the touch but not too hot to handle.

Although not as bad as NiCads Metal Hydride Batteries will build up a memory and loose there full capacity if not run down before charging.
Therefore topping up or trickle charging these batteries will soon ruin them.

I fly radio controlled planes and we are very meticulous on when we charge our flight and radio batteries.
For this very reason I am now moving to Lipos which don't have a memory buildup problem.

Regards

[mal from cessnock]

Lipos? Who distributes these Pine?

I'm sick of replacing my batteries. They pro port to last for an eon, but some don't make the grade.

Thank you Pine and Kym for your help.