NiCads in parallel?

[lctorana]

I have 2, 4Ah 3-cell NiCad packs that I would like to use in parallel for 8Ah in a direct-drive P7 project I am planning.

I know I should charge the packs either separately or in series, but is parallelling such big cells a bad idea?

At 3.6V, I haven't got enough voltage headroom for steering diodes, not even Ge or Schottkys, so is direct-parallel connection OK, or should I use a dropping resistor in series with each pack?

 

[SilverFox]

Hello Lctorana,

There is no problem using cells or packs in parallel. The problem comes when charging. You want to charge individually, or in series. NiCd or NiMh cells don't do will when charged in parallel.

Tom

 

[lctorana]

Mr Speaker, I wish to thank the Honorable Member for Rechargeable Batteries.

I have decided to go with a 0.1 ohm resistor in series with each pack in the torch, just in case of imbalance anyway. I will charge each pack separately.

Thanks for the advice. The P7 L.E.Dolphin is getting closer...