Hi, I have a solar camping 36 Led lamp. The solar panel on top of the lamp is: 0.7W 5V 70x70 mm. In direct sun light at noon I got ~ 120..130 mA (short circuit) and ~5.2V (open circuit). But it can't charge the battery... The battery is a 3.7 V Li-Ion 2000 mAh. The AC charger "pumps" 400mA ~8 hours to charge it. So the charge efficiency is only ~62%. I think this can explain why the solar panel can't charge it but I don't fully understand the details... Can someone show me a schematic of a charger I can place between the solar panel and the battery so I can maximize the power transfer? I have a 600mA 5V USB converter from 1..5V: Would this solve the problem? Thank you.