Li-ion battery+Piezo=self charging battery!

http://phys.org/news/2012-08-self-charging-battery-energy.html

Originally posted by sonhouse
http://phys.org/news/2012-08-self-charging-battery-energy.html

I find it pretty annoying that it doesn't state the percentage of energy efficiency of the mentioned mechanical-to-chemical energy conversion thus it just leaves you guessing.
It says:

“The improvement shows that achieving a mechanical-to-chemical energy conversion in one step is much more efficient than the mechanical-to-electric and electric-to-chemical two-step process used for charging a traditional battery."

but that still doesn't answer the obvious question ( Exactly HOW much more efficient is “much more efficient”? ) and it would really help to know all the percentages to make any proper sensible comparisons.

Originally posted by sonhouse
http://phys.org/news/2012-08-self-charging-battery-energy.html

A very badly written piece. I don't even think the title is correct. The battery does not charge itself, but is charged via mechanical energy instead of electricity.

Then they tested it by sticking it on someone's shoe and compared it with a similar device with separate charger and battery (presumably also on someone's shoe) - hardly the most scientific of methods.
No mention of how much power is put in or how much is lost in the generation stage and how much is lost in the charging stage (in the separate device).

But then again, if it works, lets go ahead and make them and do the science later.