How to prevent voltage drop on solar phone charger? Answered
I made a solar phone charger - cell (12V 400mA - at peak 5W) and step down DC/DC converter R-785.0-1.0 (5V up to 1000mA). and I am using it as direct charger for my phone (no batteries). When the sun is bright, everything is fine and phone is being charged almost by 1A. When the dark comes, everything is fine - no charging but also no discharging of the phone to a solar cell.
Problem is in the middle, sunlight but not so much. Voltage on cell drops to 6,5 V because converter wants more power and cell cant support that (output is still 5V but almost no Amps). Problem is, that charging circuit in phone is constantly switching on and off(as the load is pluged unpluged) and that can run down fully charged battery within 10 minutes. Is there any solution how to prevent that?- for example some kind of minimum current limiter? Or I saw using 555 timer as a charger controler, but not sure how to use it. Main goal is to prevent that oscilation.
Many thanks in advance.