I am using their BLEUART BLEUart | Bluefruit nRF52 Feather Learning Guide | Adafruit Learning System
Added in these power savings measures as well:
sd_power_mode_set(NRF_POWER_MODE_LOWPWR);
sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);
__WFE();
__WFI();
sd_app_evt_wait() ; //SOFT DEVICE “SYSTEM ON” POWER SAVE
Each LED will use about 0.3-1mA. So turn them off if not needed. The USB-C circuit will draw power eve if you have the chip shut down. So should measure the current at the battery. Without the battery and only using USB-C will not get down to uA.