Simple Li-Ion Charger

549

11:02:28

This is a super simple design for a USB charged nightlight, with a rechargeable Li-Ion battery (e.g. a 3.7V 16340). 
When the switch on the left is closed the device is charging (i.e USB is connected), until 75% of the reference voltage are reached (to avoid overcharging the battery).

When the button on the right is pressed, the battery is discharged through the LED.

Could you please comment on this design? 

a) Would this even work?
b) Will the battery explode? 
c) Is the diode necessary?
d) Areas to improve? 

As an alternative to the OpAmp I thought about using a small PIC with a analog comparator and two states (charging, full).

Please let me know your thoughts.

published 7 years ago

gogi3411

7 years ago

Tehnically speaking yes. But charging li-ion batteries requires CC,CV method. First you need to pass constant current through the battery until it reaches certain voltage (4.1V) and then slowly decrease current to keep voltage constant until current falls under the 100mA and then battery is fully charged

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