Hi everybody.
I've been messing with a street light that broke and I fixed it by replacing the PCB with a tiny85 circuit that i made.
It uses an 18650 3.7V Lithium cell. The Tiny does a great job and works reliably up to the lowest discharge voltage of the cell of about 3V.
So, wanting to stay on the cheap, I got a charging module from Amazon that takes 5V input.
My solar panel goes as high as 7V on full sun, so I added a buck converter to drop it to 5V.
So far, so good, it works, but doesn't charge fully, compared to a factory light.
I assume that it only charges while the solar panel voltage is higher than 5V, even though charging voltage is 4.2V for this cell.
Any thoughts of how to improve the charging circuit would be greatly appreciated.
3 posts - 3 participants