Hey guys Im building a bot that uses a solar panel to charge a back up battery pack. Im using a 12V solar panel with a 4 pack of AA nimh batteries which add up to about 5.2V max. Im using a diode and a linear regulator for 5V and I might put in a schottky diode on the output of the linear regulator for the battery. If I had another ADC to monitor battery voltage to remove it when they are fully charged, would this be an effective way to charge my batteries?

 

The most simple way is to use the LT1513-2 all in the chip allowing to change current and or battery voltage.
It will charge even when solar voltage becomes lower than battery voltage if power is sufficient at that low input voltage. The chip start working from 3-4V input.( pls check with spec's)

Picbuster

 

How many watts is the panel?