Read nRF51822(BLE Chip) VDD voltage and return 100 to 0% charging level
Dependents: BLE_Temp_Vdd_via_UART_TY BLE_EddystoneBeacon_w_ACC_TY51822 BLE_LoopbackUART_low_pwr_w_RTC1 BLE_Paired_Server ... more
This is only for nRF51822.
You don't need any hardware circuit. Just read internal Vdd voltage using ADC function inside of the chip.