Battery pack basics or I need help.

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Battery pack basics or I need help.

Postby ronme » Thu Mar 31, 2011 10:12 pm

How do you wire balance leads in a multi cell packs.
I have 2 ,4, 5, 6 and 10 cell Ni-CD packs and they don't have balance leads.
I think I know but I can't find any info on-line.
On the balance connecters there is one red wire and multiple black wires (ie. 2, 3, 4, 5) . I think the red goes on the first positive in the series and the blacks go to the connection point between the cells in series (ie. First black wire goes between cells 1 and 2 second black wire goes between cells 2 and 3 ect. ) but I don't know this for sure this just seems like it would be right and I would hate to blow up a battery or fry the charger if I'm wrong.
I want to be able to recondition charge my 10 cell packs. My charger will do up to 6 cells but if I treat them like two 5 cell packs (ie. Balance charge cells 1, 2, 3, 4 and 5 together and then balance charge cells 6, 7, 8, 9 and 10 together.) this is not ideal but should work fine, definitely better then nothing.
I'm I right or is there something I'm not understanding about battery packs.
Thx
ronme
 
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Re: Battery pack basics or I need help.

Postby Kozmyk » Mon May 23, 2011 1:34 am

Ooops! Didn't read the OP post properly. Sorry. :oops:

I plead insomnia.
Insanity goes without saying. :roll:
Last edited by Kozmyk on Mon May 23, 2011 3:11 am, edited 1 time in total.
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Re: Battery pack basics or I need help.

Postby kaptain_zero » Mon May 23, 2011 2:51 am

ronme wrote:I have 2 ,4, 5, 6 and 10 cell Ni-CD packs and they don't have balance leads.

I want to be able to recondition charge my 10 cell packs.


You cannot balance NiCd or NiMH packs the way you do Lipo, LiIo and LiFePO4 packs. Do not add balance leads to your NiCd packs!

To correctly balance/form/fully charge NiCd and NiMH packs, charge at 1/10c for ~12 to 14 hrs. You can then cycle them a few times and see if they come up to full power. My iCharger is set to charge NiMH and NiCd packs at 1C until full, then it drops to 1/10C for 3 more hours on what it calls a "Forming Charge" which can also be used to balance the pack. While a straight 12hrs 1/10C takes...uhm.... 12 hrs, it is the industry standard charge and will not harm your NiCd and NiMH packs as the charge rate is low enough so as not to cause any significant warming/pressure buildup. If you have a 1000mAh NiCd pack, charge it at 100mAh (0.1A) for the 12 or so hours. After that you can cycle your NiCd using 1C charge/discharge rates or thereabouts. Normally you will discharge to 1V per cell, but if you are trying to revive old NiCd packs, you might need to go lower if they are not responding.

[edit] I should point out while typical hobby chargers have balancing circuits built in, they only have that mode accessible in the Lithium cell charge mode, you will not find it in the NiCd, NiMH or PB settings as such packs do not use balance leads. If you were to attempt to charge a NiCd or NiMH pack on the LiPo setting... you would grossly overcharge your pack.

A quick trip over to http://www.batteryuniversity.com should net you some valuable information on the care and use of all types of rechargeable batteries.


Regards

Christian
"I'd like to live as a poor man with lots of money."
-- Pablo Picasso
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