Build a NiMh solar battery charger

Thread Starter


Joined Dec 14, 2017
Good day, I'm working on a solar charger project. I want the charger to charge the batteries normally until they are fully charged and then switch or decrease into a trickle charge. The batteries is used for LED lights so if it is possible it would be nice to have the lights switch on when it's dark.
If there is a simple but good circuit I'm all ears. I am a engineering student so I'm not all lost but this is my first time building an actual home project so I don't want to mess it up with unnecessary mistakes.

The Specs

Solar Panel :

The measured output voltage is 25.5V
The Voc voltage is 17.5V
The Isc is 10mA

The Batteries :

3 x 700mAH - NiMh batteries, all of them is 1.2V.
The normal charger uses 1.47V and 150mA to charge.

Is there any simple circuit that will do the job with the trickle charge included, the day/night option is not compulsory.