How does reverse polarity protection work?

cleetus03 · Oct 18, 2009

Was wondering if someone could explain this concept (reverse polarity protection) to me in layman terms?

For example, I read that if you put the batteries in backwards in a minimag led, the moment you twist it on.......poof?

I am assuming flashlights without reverse polarity protection are the minority?.....Is this correct?

Appreciate all the help and info yall can give me!

Marduke · Oct 18, 2009

Most reverse polarity protection is a physical ring which allows a positive nipple to contact the board, but won't allow the negative end to touch.

Most lights have no protection. Don't assume it does unless it explicitly states so.

kramer5150 · Oct 18, 2009

As marduke says... usually a ring or raised bumps around the + contact. They prevent electrical contact when the cell is installed backwards. Some DC-DC boards have diodes in line with the +ive input to protect the circuit, they present a Vdrop to the circuit though so a physical type of prevention is better. I always bypass the diodes on my boards to keep the 7135 chips running in regulation for a longer time.

cleetus03 · Oct 18, 2009

appreciate the reply's and apologize for putting the thread on the wrong subforum...

BackBlast · Oct 20, 2009

You can also use FETs to provide reverse polarity protection with a minimal drop compared to, say, a straight in-line diode.

How does reverse polarity protection work?

cleetus03

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Marduke

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kramer5150

Flashaholic

cleetus03

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BackBlast

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