Why do manufacturers recommend against charging NiMH batteries in parallel?

 

I believe it is because of cells becoming unbalanced or varying cell capacities...whatever, I do it.

If I ever find there is a problem, I will just build my machine to jump between the two batteries if one gets too low.

 

Thanks for the quick reply. I thought that it might have had something to do with the unbalanced cells hoarding all the charge current. I was thinking that you could mitigate that problem with some creatively placed resistors or something.

Thanks again.

 

I just drain my cells regularily to almost minimum and then charge them up (I should probably charge them to nominal or just under nominal capacity so that no under-capacity cells get stressed. Battery discharge is a non-linear thing so you can't use external components to try and correct for it. Just take good care of your cells.

 

For many years, my "beach amp" had its two series strings of 6 AA Ni-Cads connected in parallel without any problems. I used a National Semi stereo amp IC (discontinued now) bridged for each channel and got about 6W per channel into 4 ohm speakers all day long.
After being on trickle-charge for about 20 years, every single cell ended its life shorted.
The rechargable electric screwdriver I inherited must have been charging for at least 25 years and still works fine. It doesn't have paralleled battery cells.

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Uncle $crooge

 

audioguru, are you saying that from your experience, it would be alright to charge in parallel?

 

Since I had two strings of 6 battery cells, and the strings were in parallel not the individual cells, then they probably averaged to be the same. Both strings had weak cells and strong cells.

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Uncle $crooge