18650mA Battery Charger Voltage Protector Circuit - Simple Electronic Project





Diagram of High Current Li-Ion Battery Charger Circuit diagram


Components Needed for this Project:

You can get the components from any of the sites below:

  1. BC548 Transistor [See Buy Click Amazon]
  2. TL431 Voltage Regulator [See Buy Click Amazon]
  3. TL431 Voltage Regulator [See Buy Click Amazon]
  4. LED 5mm [See Buy Click Amazon]
  5. BD140 Transistor [See Buy Click Amazon]
  6. 4.7 Ohm 2 watt Resistor [See Buy Click Amazon]
  7. 1k Ohm Resistor [See Buy Click Amazon]
  8. 20k Ohm Resistor [See Buy Click Amazon]
  9. 680 Ohm Resistor [See Buy Click Amazon]

*Please note: These are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

Related Basic Electronic Mini Project Circuit Diagram:


Working Principle




Frequently asked questions

What is the maximum amp of a Li-Ion battery?

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.

How much current is high current?

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.

How many amps is an 18650 Li-ion battery?

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.

What is the disadvantage of a high current?

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).

Can I charge a 3.7-volt Li-ion battery with a 5-volt charger?

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.

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