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Question about using LiPo Batteries Answered

I would like to use a 3V Solar cell rated at 45mA to charge a LiPo Battery (3.7V) rated at 200mAh. am wondering. How long should I allow this to sit in direct sunlight to charge without overcharging the battery? I would also be adding an inline switch to shut off current from the solar cell.
Here are the links to the products I would be buying (In case it helps)

Solar Cell: (Its about half way down labeled "3.0V 45mA Solar Cell")

Battery (Note I'm only using one)



Agreed, lipos are very fussy. I have alot of them in rc cars & planes. The only lipo chargers I could find on sparkfun were 5v input. You could get 2 panels and wire them together, than put that through a voltage reg to 5v. Then use that with a charging board.


First you will need a charge controller for the battery. LiPo batteries are vary picky about charging. So use a charge controller. don't try to time it. Next you'll need to supply that contoler/battery with slightly more voltage than what the battery puts out. 3V on a 3.7V battery isn't going to do anything.

So would something like this work?


No. Look at the fully charged voltage rating on that unit. It charges Lipo batteries till they reach 4.2V. That would destroy a 3.7V battery.

If that charges it to 4.2V, would this battery work with it? it says that its output is about 4.2V.


That would work as long as the battery is able to be charged to 4.2V.

Without electronics, a 3V panel can't charge a 3.7V cell.