PAGE 125 OF 150 · POWER SUPPLIES & BATTERIES
Rechargeable Li-ion Cells
Li-ion needs proper protection and charging.
LED SYMBOLTriangle points from anode to cathode; the arrows show light leaving the part.
Characteristics
A lithium-ion cell is 3.7 V nominal, 4.2 V when full and should not be drained below about 3.0 V. Common 18650 cells hold about 2,000 to 3,500 mAh.
Safety
- Charge with a proper charger, such as a TP4056 module, which gives constant current then constant voltage to 4.2 V.
- Use protected cells or a protection board against over-discharge, over-charge and short circuits.
- Never short, puncture or charge them unattended.
Damaged or swollen cells should be taken to a recycling point, not thrown away.
REMEMBER
Li-ion needs a proper charger and protection.Try it yourself
Sketch the circuit on paper first, calculate the values, then build it on a solderless breadboard using a low-voltage supply. Measure with a multimeter before you make anything permanent.
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