Why do flat batteries use the case as positive instead of negative

derek10 · Jun 17, 2016

For example most 18650 use the case as negative and the positive as an isolated pin, but some flat batteries are reversed - the metal case is positive and a isolated pin as negative. Why is that?

Thank you

CoherentRays · Jun 17, 2016

I haven't seen that before. What batteries do that?

Ed

derek10 · Jun 17, 2016

All Li-ion prismatic cells (not LiPo, those seems to use two separate pins and the metallic envelope is isolated) that I saw are so. The small pin at center is negative and the whole case is positive :S

ChrisGarrett · Jun 17, 2016

'Why ask why?'

Why is it called the 'foul pole,' since when you hit it, the ball is in fair play?

Why is it called a '.38 Special,' when the bullet is actually .357" in diameter?

The answer?

'Just because.'

Chris

Lynx_Arc · Jun 17, 2016

For the same reason all button and coin cells use the case as + I guess.

ChrisGarrett · Jun 17, 2016

Lynx_Arc said:
For the same reason all button and coin cells use the case as + I guess.

50-50 chance either way, right?

You say po-ta-toe, I say po-ta-ter.

Chris

m4a1usr · Jun 17, 2016

I'd have to say it was design restrictions in devices initially. You see this in watches, mini alarm clocks, and other miniature electronics where the cover is either plastic or not designed to be a conductor, just a dust/dirt/moisture protector.

Why do flat batteries use the case as positive instead of negative

derek10

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CoherentRays

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derek10

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ChrisGarrett

Flashlight Enthusiast

Lynx_Arc

Flashaholic

ChrisGarrett

Flashlight Enthusiast

m4a1usr

Enlightened

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