High Current Li-Ion Battery Charger Circuit | 18650mA Battery Charger Voltage Protector Circuit

They are commonly available with capacities ranging from around 18650 mAh up to 18650 mAh or more and discharge rates from a few amps up to 3 or 4 amps for high-performance applications.

Any electrical device used on a house wiring circuit can, under certain conditions, transmit a fatal current flow. While any amount of current over 20 milliamps (0.02 amp) is capable of producing painful to severe shock, currents between 100 and 200 mA (0.1 and 0.2 amps) are lethal.

18650 batteries can produce between 2,500 mAh (2.5 amps) and 3,500 mAh (3.5 amps). A higher amp output means that the battery produces more power. Consider this example: If you have a 4.2V, 3,600mAh, 18650 battery.

For the same power, high current requires thick, expensive conductors, and high voltage requires thick insulation and substantial air gaps between conductors, plus it's dangerous to work with (any high-power device is dangerous).

Charging a 3.7V lithium-ion battery with a 5V charger can potentially lead to overcharging and, in turn, damage the battery or, in extreme cases, cause a safety hazard. Lithium-ion batteries have specific voltage ranges for charging and discharging to ensure safe operation.