Low Voltage Charge controller

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set321go
Posts: 1
Joined: Thu Apr 26, 2012 10:42 am

Low Voltage Charge controller

Post by set321go » Thu Apr 26, 2012 11:54 am

Hello,

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.

My Problem:
I have been looking at voltage regulators http://www.datasheetcatalog.org/datashe ... 068_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

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