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Author Topic: Why do batteries have a limited number of charges?  (Read 3346 times)

Ellingson, Kenneth L

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Ellingson, Kenneth L  asked the Naked Scientists:

Chris

Why do batteries have a limited number of charges?

Or

Why does batteries performance decline over time?

Knute Ellingson, Chicago

What do you think?


 

Offline Pumblechook

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Why do batteries have a limited number of charges?
« Reply #1 on: 13/10/2008 23:26:33 »
All to the do with the chemistry.

http://www.batteryuniversity.com/
 

Offline techmind

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Why do batteries have a limited number of charges?
« Reply #2 on: 14/10/2008 22:59:50 »
The most common way of sending a rechargeable battery to an early grave is by overcharging it. In the case of NiCd and NiMH the battery vents hydrogen gas when overcharged, so it's loosing a chemical with which it stores energy. Modern "fast" chargers (anything which charges in 3-4 hours or less) sense an abrupt rise in temperature and/or a change in voltage on the cell to detect end-of-charge. Occasionally this sensing glitches which can result in overcharge.

I believe serious overcharging of Li-Ion/Li-polymer can lead to fire, but I'm less familiar with the mechanism (yeild Li metal?).
 

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Why do batteries have a limited number of charges?
« Reply #2 on: 14/10/2008 22:59:50 »

 

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