The battery has 5 wires, 2 red hot wire, 2 black ground, and 1 white. I assume the white is used by the cpu to monitor charging? battery temperature?
I measured 3.9 VDC red-black on battery power, and 4.1 VDC when the battery was charging through its USB port.
And 3.9 VDC red-white on battery power, 2.7 VDC when charging. While white-black was 0.0 VDC on battery, and 1.3 VDC when charging.