Why didn't you make this an MPPT?
For low power solar charging of lithium ion's, its not necessarily a better way to charge. For information on why we did not design it as a true MPPT, read our design notes!
BUT I HEARD THAT MPPT IS THE BEST!!
For large multi-watt solar arrays that are charging lead acid batteries, you will want to get an MPPT charger. For small cells, its not necessarily more efficient. For information on why we did not design it as a true MPPT, read our design notes!
What solar panels can I use?

Use any rigid, flexible, monocrystal, polycrystal, etc panels with 6V rating (12 'cells') for the best performance

We've tried 5V panels and they don't work. 5.5V panels sometimes work, 6V is really the best!

Can I charge with a solar panel on my windowsill?
The charger will draw as much current as possible, but the efficiency of the panel will be much lower. Solar panels must not have any glass or shade to work efficiently, they must be outside, pointed as best as possible directly at the sun!
Both the Charge and Done LEDs are on and the battery is not charging.

This is a fault condition detected by the charger.  Most often it is a battery problem.  This can happen if the battery is allowed to discharge completely.   The protection circuits on some LiPo cells require the battery to be disconnected in order to reset the circuit after an over-discharge cutoff event.  Often just disconnecting and reconnecting the battery will allow it to charge again.

This guide was first published on Jul 29, 2012. It was last updated on Jul 29, 2012.

This page (FAQ) was last updated on Nov 27, 2020.