Currently, I have a pair of 6V 0.5W solar panels (from the solar pocket factory) wired in parallel. I've replaced the 2 AA battery pack with a 3 AA battery pack and am using brand new eneloop 1.2V NiMH batteries.
I have the panels going through the a pair (in parallel) of BAT-46-TR Schottky Diodes (100V, 150ma, Vf 450mV) to prevent the batteries from discharging over night.
I've only tested it for a few days, but I'm having mixed results. One day, I was able to charge my iPhone 5 fully from about 40% charged. The next two days, I've only been able to charge about 10%.
Any ideas if:
- 1. The Schottky diodes limiting my current to the batteries too much?
2. I should be looking to do something like the pseudo mppt here: http://learn.adafruit.com/usb-dc-and-so ... sign-notes ?
3. Need to increase the number of panels?
4. Get lower voltage panels?
I want to use the NiMH batteries to keep costs down and avoid needing the LiPoly charger.
Thanks,
Jon