NiMh battery charge controller

Thread Starter


Joined Jul 11, 2018
Hello to all,

I have a system that work with external power supply with output voltage of 16-32Vdc and 2x NiMh batteries (24V@9Ah) in parallel for backup.
in fully power ON the system takes around 240-360W (10-15A).

I need to find a over-voltage protection circuit or charge controller for the batteries so they will charge up only when the battery voltage will be less than 20V and stop charging when it reach to 28V.
the most important, the protection circuit need to shutoff when the main power is OFF and the batteries kick-in, I guess I will need a relay for that .

I thought about solar panel's MPPT as a solution but I'm not sure it suitable to my needs
or a DC/DC charger but it to heavy for me, I need more Lighter solution.

can you please help me find a good solution for the problem ?
I'm open to any suggestions

Thanks :)


Joined May 3, 2013
Do you have to parallel the batteries? It will be much better to put them in series and use a buck convertor to drop the voltage from 48 to the required value.
Controlled charging of batteries in parallel is lot more complex than that in series.