1: Use 3.7V18650 flat-head lithium battery (no protection board), the battery must be connected in parallel, remember to burn the motherboard in series, test the battery voltage before loading, as long as one battery is bad, it will affect the whole battery.
2: Charge and discharge protection, lithium battery protection IC built in the circuit board, over voltage protection, over current protection, under voltage protection, etc.
3: Charging input requirements, 5V1A or above charger or 5V constant voltage power supply can be used as charging input power.
1. Although mobile power can fill most mobile phone models, it is not universal. Not all models can be perfectly supported. There may be very few models that are not compatible. I hope you can understand more.
2. After the first power-on, there is no output, you need to use the charger to charge and activate.
1 x Dual USB 5V 2.1A Micro Type-C for DIY Power Bank 18650 Charger Board