Built-in protection circuit (PCM) prevents over charging/discharging.
Fitbit Inspire 1, 2, 3, Inspire HR Smart Watch Rechargeable Battery - 3.7V 50mAh
Fitbit Charge 2 / 3 FB407 Smart Watch Battery - 3.7V 80mAh LSSP411415 FTC200SL
1.2V 12 Slots AA AAA Battery Charger Fast Charge Discharge Smart LCD...
For 3.7V Charger Liion Battery USB Charge Portable Smart Battery Charger 4-Slot
MPPT Solar Charge Controller Smart Automatic Adaptation 12V 24V 10Amp High Efficiency Tracking LCD Display Multiple Protection PVC Aluminum Alloy for Solar System Outdoor RV
