Powerbank reverse voltage protection

[skmdmasud]

Hi..
I bought this power bank case with circuit, last time i inserted the 18650 battery reverse way and it burned the circuit. This time i planned to use a diode for reverse polarity protection. But there is a problem of voltage drop. Which means i will get less output but that's ok. The mail problem is when i will charge the power bank it will charge .6v more.

What should i do.

Regards.

 

[rjenkinsgb]

With a diode in series with the batteries, it either cannot charge or cannot discharge, depending on the diode polarity.

The 0.6V or so offset will also mess up the voltage control, not charging the battery properly or switching off seeing a dead battery when there is still plenty of power available.

Just be careful with the battery polarity!

 

[Visitor]

EDIT: I don't think this circuit will work where you need to CHARGE a battery. But it's very simple reverse polarity protection where you are connecting external power to a circuit board.


Use a p-channel mosfet for reverse polarity protection. A logic-level mosfet with low DS resistance will result in virtually no voltage drop.

The circuit shown will work great for circuits under 9 volts. For higher voltage circuits, a zener diode and resistor should be added to protect the gate. Search for "p-channel mosfet reverse polarity protection" for more detailed discussion.

 

[Pommie]

I'd go for the simpler solution of not inserting the battery backwards. You fried the first one and, presumably, bought a second. Just do it right.

Mike.

 

[Nigel Goodwin]

I'd go for the simpler solution of not inserting the battery backwards. You fried the first one and, presumably, bought a second. Just do it right.

Exactly - you should only be fitting batteries once - just do it right, it's hardly complicated.