The Verge posted a cool list of cheap gadgets that don't suck, and my impulse purchase was these USB-rechargeable lithium 9-volt batteries from one of those gibberish-named factory brands on Amazon. " I'm not going to promise these are perfectly safe," says recommender Sean Hollister, but I have bought a pack all the same. Customer reviews are at 4.3, whatever that's worth these days.
One from Paul Kersey stood out:
So why not 5 stars? There are a couple quirks that make using them somewhat inconvenient. For starters, the charging method is unusual and not explained in written instructions. Each battery has a flip-open door on the bottom–really just a plastic tab on hinges. THIS is the what you plug into a standard USB-A port. The contacts are on the inside of the compartment, and they should face up when you plug in the batteries for charging. This is an awkward design since many USB ports are too high off the ground to support a 9-volt battery while it's inserted in the charging port. If you charge these batteries in elevated charging port, they hang down supported only by the door/charging tab. Over time, the stress of supporting its own weight seems likely to reduce the usable lifespan of these rechargeable batteries.
Previously at BB, rechargable Lithium AA batteries are a reality too, and Project Farm figured out the best.