Very simple NiMH Charger..

[Klabbis]

Hi!

So I wan't to create a simple 1/10 C charger for one of my power tools (a drill) and it is rated at 14.4V and 2200mAH so I should charge it at 220mAH then right?

Is it as simple as just using a 24V powersupply with 1 resistor to get the correct current?

And the resistor shuld be around 43 ohms (24-14.4/0.220)
AND I guess it must be able to handle >2Watts..

Are my calculations correct?

 

[Phasor]

This is the very simplest form of charger, however, as the battery charges, the current will decrease.

I think there is a better solution on this datasheet:
https://www.electro-tech-online.com/custompdfs/2003/07/LM117PDF.pdf
(I refer to the "50mA Constant Current Battery Charger" on page 17).

Subsitute the 24 ohm resistor for 5.6 ohm (0.5W minimum). This should give you 223mA.

 

[Klabbis]

Thank you!

I'll give it a try....