The truth is, I don't really need a fast charger; for now a 50mA charge seems more than enough. It's also doesn't seem that important if the batteries reach full charge; unless this damages or limits their life-span in any way. I read that you can easily damage NiCd batteries because of the memory if you charge them wrong; but this doesn't seem to apply to NiMh batteries.

I think I'm going to leave it as it is... taking the batteries out at 3V when the LED lights up.

 

The truth is, I don't really need a fast charger; for now a 50mA charge seems more than enough. It's also doesn't seem that important if the batteries reach full charge; unless this damages or limits their life-span in any way. I read that you can easily damage NiCd batteries because of the memory if you charge them wrong; but this doesn't seem to apply to NiMh batteries.

I think I'm going to leave it as it is... taking the batteries out at 3V when the LED lights up.

At C/10 there's no great rush to take them out of the charger, at C/20 you can probably get away with a week or two.

 

You could add an emitter resistor to create a traditional constant current source less dependent on transistor gain.

 

One brand of batteries is 1300 mAh, another is 550 mAh, and the third is just 350 mAh.