how efficient is a rechargeable battery ?

Space | 03:10 Mon 17th Apr 2006 | Science

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I was reading a few articles about hybrid cars and regenerative breaking today...
and wondering how much energy is wasted when stored into a battery to be re-used later.

In other words: what is the efficiency of a rechargeable battery?
For every unit of power spent charging it, how much power will I get out of it later?

I suppose it depends on the battery type and how fast it is charged/discharged, but I haven't found any figure so far..
I suspect it's far from 100% because I noticed batteries for domestic use (such as Ni-MH AA) dissipate quite a lot of heat when being recharged or used...

science in 5,10,20,100 years..

How heat affects objects

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Dacetine

Batteries differ but a rule of thumb is that 40% of the charging energy is wasted. So to fully recharge a battery from flat requires 140% of its nominal capacity.

http://www.jaycar.com.au/images_uploaded/recharge.pdf

Despite this, rechargeable batteries are more environmentally friendly than disposables such as alkalines because the energy required to manufacture the physical components of the battery is very much greater than the energy stored by it. So reusing a battery avoids the need to manufacture a whole new one.

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