I would like to charge a battery using a solar panel. My only real requirement is that my battery has to have an output voltage of 5V I would like to make a charge controller to prevend overcharging and damage to the battery. I have limited knowledge of making circuits but i feel its a good place for me to start.
What i think I need:
- over voltage
- voltage regulation
- current regulation
- preventing back flow to PV cell
have i missed something?
What i understand:
I can use a Diode to control the flow from the PV and prevent it going the other way, I can use resistors to control the current, and I can use a charge controller to regulate the voltage going to the battery.
I have been looking at voltage regulators http://www.datasheetcatalog.org/datasheets/228/390068_DS.pdf but they seem sensitive to large fluctuations in voltage, the one above can tolerate +-4% apparently. If I have a 12V PV cell the voltage could potentially vary from approx 7V to 15V, how can I stabilize this voltage before sending it to the voltage regulator?
thankyou for your help