replacing sub-c batteries

replacing sub-c batteries

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Barreti

Original Poster:

6,680 posts

238 months

Monday 16th August 2010
quotequote all
This is a bit of an odd one guys, but I figure if anyone can advise me on batteries you guys can.

I have a rechargeable torch which has been great but is now not holding charge.
I've opened it up and found a pair of Energizer EP1300 batteries soldered together.Although the individual batteries state they are 1.2v 1300 there is a label wrapped them both stating ni-cad 2.4v

Their measurements and the tags to allow them to be connected in series make me think they are sub-c but I can find nothing if I google Energizer EP1300

There seem to be some considerably higher power sub-c batteries around and very few 1300's, if the charger is output 2.4v / 1300ma could I upgrade the batteries ?
It wouldn't really matter if it took longer to charge, its just an emergency household torch which is always plugged in anyway.

If you can recommend a pair of replacements I'd love you forever laugh

Morf

215 posts

171 months

Monday 16th August 2010
quotequote all
Are you sure that the charger is 1300mA?

The reason I ask is that the standard charging for Nicads etc is to charge for 14 hours with a current of C/10, where C is the battery capacity(see http://www.electrodynam.com/rc/totm/totm1097.shtml for example).

So, 1300mAH batteries should be charged at 130mA for 14 hours (hence my question about the charger). The voltage doesn't matter (within reason) as long as it's higher than or equal to the cell voltage, 2.4V for two cells in series is fine.

Anyway... practical answer to your question: yes you should be able to use higher capacity cells and just increase the charge time. So, for instance, if you used 1600mAH cells you'd want to charge for about 17 hours.

There's a point where this all starts to fall down, of course... I wouldn't want to try to charge 3300mAH cells at 130mA, they'd probably go flat before they were fully charged!

CPC sell 1600 tagged sub-c's ( http://cpc.farnell.com/jsp/search/results.jsp?N=41...) and I certainly can't see you'd have any problems in swapping to those.

HTH, loving forever is not necessary!

Barreti

Original Poster:

6,680 posts

238 months

Monday 16th August 2010
quotequote all
Ah, the old grey matter aint what it used to be.
I've just been and checked the charger. It states Output: 2.4v 120ma

So that means I should be OK with a pair of 1600 batteries then?

Morf

215 posts

171 months

Monday 16th August 2010
quotequote all
Ah, that sounds much more likely!

I can't see any reason why you should have any problems with putting in 1600mAH cells, it will simply extend the charge time a little, but if you keep it on charge all the time that shouldn't matter (although keeping rechargeables charging all the time is not good for them).

I suppose I should put a disclaimer on here, though... don't blame me if it doesn't work!

Holst

2,468 posts

222 months

Monday 16th August 2010
quotequote all
Morf said:
Ah, that sounds much more likely!

I can't see any reason why you should have any problems with putting in 1600mAH cells, it will simply extend the charge time a little, but if you keep it on charge all the time that shouldn't matter (although keeping rechargeables charging all the time is not good for them).

I suppose I should put a disclaimer on here, though... don't blame me if it doesn't work!
Sounds right to me smile

Barreti

Original Poster:

6,680 posts

238 months

Monday 16th August 2010
quotequote all
Ordered a pair from CPC. Thanks very much for your help Morf

Morf

215 posts

171 months

Tuesday 17th August 2010
quotequote all
No problem. Thanks also to Holst for confirming my thinking... you know what it's like, the more you think about the answer the less certain you are!

Be careful when soldering them, if you keep the heat on for too long you can damage the cell (like any other electronic component). If the joint doesn't solder well first time, let it cool down for a few minutes before you try again - don't keep trying straight away because that leads to heat sink into the cell which causes the damage.

As long as you're confident and make sure your iron is hot so it heats quickly you shouldn't have any problems though. I've done them myself in the past as a cheap way of making battery packs for a radio controlled car.