My battery drains too fast

Step 1: Measure actual power draw
Use a USB inline power meter to measure real current draw. This immediately shows whether you have a software config problem or a hardware issue.
Expected draw by hardware
The figures below are approximate field measurements and vary with firmware, settings, and transmit duty cycle - measure your own device for an accurate number.
Hardware
Typical active draw (approximate)
ESP32 (T-Beam, Heltec), no display, no BT
~40-55 mA
ESP32 with OLED display on
+10-20 mA
nRF52840 (RAK4631, T-Echo, T114)
~8-15 mA
Power drain checklist
Screen on all the time? Set a short screen timeout (e.g. 10-30 seconds) so the display sleeps. Note: a timeout of 0 usually means never sleep - avoid it on battery.
Bluetooth enabled? Disable if not needed.
GPS polling? Disable or set a long interval.
WiFi enabled (ESP32)? Disable.
Position broadcast interval too short? Set to 30+ minutes on battery.
Battery sizing
Battery (mAh) divided by draw (mA) = hours of runtime. 1000 mAh at 40 mA = 25 hours; at 10 mA = 100 hours. Switching from ESP32 to nRF52840 hardware typically gives roughly 4x longer life on the same battery (approximate; the exact ratio depends on your settings and usage).