90 second charge time
 

I saw this in another forum and wanted to post it her:

http://flashcelldriver.com/specs.html

500,000 cycles and it takes 90 seconds to charge.

That's very interesting. Wonder if it's really a battery.

It is capacitors. I just did a yahoo search for flashcell. It probably uses a few of those supercapcitors.

How many joules are they?

There isn't a lot of info about the capacitors used in that power tool. I know Maxwell and Enerland makes such capacitors. There are a few other companies that makes them as well.

http://www.maxwell.com/ultracapacitors/index.asp
http://www.enerland.com/product/p4.php?num1=4&img=y

thats cool, I need a screwdriver that doesn't need all night to charge

If it's just a cap, it must charge to a much higher voltage and use some kind of regulator to output the steady 5.4v. Otherwise, the voltage would fall far too rapidly. After 1/5 of the cap's time constant, the voltage is already at 63.2% of the initial charged voltage. Yeah, gotta be something like that to provide anything near a steady output for any length of time. Also, current draw can't be too high at 5.4v and 220rpm. 35 lb-in is 560 oz-in... not very much really.