Here is what I have when connected and charging the Batt and when the usb is disconnected. I use these 3.7 to 3.85 v batteries 450mah-1100mha. They work perfectly and I recharges very fast.
Typically its 4.08 vdc when plugged in and charging it 4.1 thats with a BLE connected and functioning. Plugging in and unplugging doesn’t drop the connection either.
HTH
GL
