yep, well its not quite that simple. USB has max 500ma @ 5V so 2500mW the sabre (disregarding the IV stage which will use higher voltage) requires several regulated voltages some @ 3.3v and some at 1.2v, but in order to get those lower voltages they will have to be regulated down, so without knowing the exact design its hard to say how much of that voltage drop will just be thrown off as heat in the process. but in order to use the balanced output, even if it doesnt have the balanced out (which i assume it does) in order to make use of the DNR it will also need to have some voltage on the negative rail. your math is also quite neat, as it assumes that they can find a way to use every drop of energy in each cell equally so they all run out at the same time (not going to happen).
in short though, yes at least that and i find it highly unlikely that they would be shooting for 10hrs, possible i guess, but unlikely. some polymer batteries will get much larger than that, its unlikely to be lifepo4, which s my personal favorite, because it would be too large given the size they have said the unit will be, so has to be lipoly or one of the more energy dense chemistries. put it this way, the battery in my one will put out 70A @ 14.4v all day long (well till it runs out, which at over 1000W would be much shorter hehe) the power is not a problem for modern lithium batteries. they will put out much more than that for short periods
taken from the linear website from some random battery charge manager (the first link that came up)
Quote:
the charger must limit the current drawn from the 5V USB bus to either 100mA (500mW) or 500mA (2.5W) depending on the mode that the host controller has negotiated.
so those are the 2 modes a usb bus generally has, i was just double checking as i had both 500mA and 500mW in my head, but now i know why.
but now i'm just going to sit back and see what they come up with
Edited by qusp - 11/26/11 at 5:06am