stoopkid:
That's pretty neat, I might give that a try. I'm just worried about the reliability of an nobrand chinese battery of such apparent complexity.edit: it also appears to be pretty big. Again, I have no real requirements but I wonder if there are low capacity ones that are smaller.
I'm sure there are probably branded versions. For my potential app, I need 12+ hours of continuous runtime (preferably 2+ days), and using only one charger port was desirable, since I generally need to charge camera batteries as well, and hotels don't always have that many outlets.
However, if you don't need that much capacity, as I said you can pick up 9v batteries fairly cheaply. Note this battery only has a capacity of 175maH, while the battery I quoted had 8500maH at 9v: http://www.amazon.com/Energizer-Eveready-00916-NH22NBP-Rechargeable-Battery/dp/B000ES8A8M/ref=sr_1_1?s=electronics&ie=UTF8&qid=1344859289&sr=1-1&keywords=energizer+9v+rechargeable.
Bear in mind that most batteries these days are made in China, though I imagine as the Chinese implement environmental and worker safety laws, that the location for manufacturing will change to the next lowest bidder.