05-20-2017, 06:48 PM
(05-20-2017, 02:48 AM)Little_Johnny Wrote: im making a Pine64 tablet with a c4 labs screen case, i want to put a 5v solar panel with a 5v 2A voltage regulator on the back to charge the 3.7V Li ion battery, im thinking about using a usb plug from the voltage regulator to the pine64 board, my questions are is this possible and do i have the voltage and amps correct to charge?
What sort of solar panel... is it one of these fold out ones with built in USB sockets? If so, skip the next paragraph, which focused on a self-build system. One of things you didn't explain though was what sort of useage was this tablet going to get, which will dictate how much charge it will need. If it's something like an hour or two of use a day, and it being off the rest of the time... then this might actually be practical, even on a cloudy day.
Your volts and amps are indeed right to provide the 5v to the pine64 to power it and charge the battery via the microUSB port or DC_IN euler pins, but my question would be although you have a 2A capable regulator... what is the amperage of your solar panel, and will it provide say at least 1A at 5v. If you're cheating and using a voltage regulator instead of a proper solar management system, the solar panel needs to be a higher voltage, say a 9-12v panel, and your buck regulator able to accept that as the input voltage. Then you might have more luck. As things stand at the moment, you would be rely on the solar panel to be putting out more than 5v so the regulator has the overhead voltage it needs (to get 5v of a switching regulator, unless it is a hybrid linear/switching or passthrough capable regulator, it needs more than 5v in).
As Macrus suggested, you would probably be better off with a 12v system... as you can get small 12v panels really cheap (20w should just about do it, although 40w would be better - more is better, especially for overcast days), and then use a charge controller and a SLA/car battery. Bigger and bulkier, but the best way if you want reliable solar power. But obviously won't be fitting onto the back of the pine64 case.
