NiMh battry charging

[Felino]

I have, in front of me, a 3.6v 600aAh NiMh battry.

OK, I have a knolagr of electronics, but never with charging NiMh battrys. This is for a porable project, but not a game system.

How do I chard this, I have read to charge them a C/10 (C being the capactiy of the battry) for 1.5 times C/10.

Now, i have a handy 3.0v 400mAh powerpack laying around, but no 3.6. Will this work?


Thanks
Felino

PS, not worth another topic, but are there any other old laptops about the size of a libretto? Like, really old.

[timmeh87]

those power bricks dont have infinite power like some people assume. they actually have very high series resistance in them, and the voltage drops steeply as you draw more current through them

therefore, if you hook any power adapter up to a battery, it will find a stable point where the voltage is the same as the battery's and the current is whatever current happes to flow at that voltage.

in your case, at 3.0v 400mA will flow, but at 3.6V you would expect less, maybe 300mA.

C is the capacity of your battery, so C/10 is 60mA, not 300. however, you can still use this to charge the battery using the formula

(C/300) * 1.2 hours

which will put 1.2 times the capacity of the battery into it. this makes up for resistive losses and ensures that the battery is full without overcharging it too much.

*note that i totally made up the number 300mA, you would have to measure it yourself.

[Felino]

Ok, thanks for the info, same goes for NiCd?