Charging NiMH battery

[derekffc]

Hi guys,

Need some help regarding charging a battery with the requirements - needs to be simple so it will fit into the rest of my circuit(small), has to be made up of parts that are readily available as it needs to be finished in two days.

Battery is 3 cell NiMH 280mAh 3.6V(total not per cell). If anyone has any prior knowledge about this or simple circuits that work then I would love to hear from you.

Thanks

PS in the attachment is one method I have tried to no avail.

 

[BobK]

Read the charging section in this article:

http://en.wikipedia.org/wiki/Nickel–metal_hydride_battery

Your best bet is to trickle charge at < .1C which would be about 20ma. Use a 5V supply and then calculate a resistor to limit the current to 20ma, i.e. (5V -3.6V) / 0.020 = 70Ohms. A more standard 68 Ohm resistor would be good. It will take overnight to charge this way. A quicker charge is much more complicated as you can see from the article.

Bob