Good day to all.
Just looking a little more closely at the hardware schematic and see something that scares me: Diode D3 bypasses the Lithium Battery Charger circuit and dumps raw USB supply voltage directly into the battery.
This just seems wrong!
Vusb ranges anywhere from 4.2V on up to 5.2V (cell-phone charger). Most common is somewhere near 4.4V - 4.9V.
I have 2 issues with the diode:
No current limit. If the battery want to, it can suck as much current as it wants. With some PC motherboards, that can be several Amps (they cheaped-out and didn’t put in current limit).
Battery voltage too high if Vusb exceeds 4.7V or so.
I’m curious: why is that diode there?