Originally Posted by nunjabusiness
I'd be very interested in something that would plug into a USB port on a desktop or laptop or any USB power supply.
If you have USB3.0 it "might" be possible as that has higher current carrying (3.6W) potential than USB1 and USB2.0 which are ~500mW at best. That's one disadvanage to the big ass battery in these things, which I think are 7.2V, so they usually require a higher input voltage (hence why we get 12V in). Even with USB3.0 though, we are still looking at long (10x+) charging times versus the wall-wart.
It's "technically" possible to step up the current USB 5V to 12V, but the power level is so low that it would take forever and a day to charge ( or about 48x longer than the current 12V/2A wall charger)
without a proper teardown though, it's tough to tell what the charging circuit looks like on the board. My guess is it's a 12V / 7.2V buck charger as it's cheaper than a boost/buck to implement. My bigger question about the internal charging circuit though is what it actually draws in terms of power...the wall wart is rated for 12V/2A, but those are usually overbuilt to prevent them from blowing up. Hoping it's closer to 1A draw, but again without knowing what the charger chip is, there's no (Easy) way to determine this without probing the connections.
I'm a hardware guy, so don't trust any ideas I may have about software.
Too many phones and tablets to remember.....