slbaker wrote:. . . . building a simple 0-to-120V power supply using a variac, a bridge rectified,
a current-limiting resistor . . . .
Let me get this straight: You're going to run a "Fun with electricity" experiment with lithium batteries that cost. . . ? You DO have a fire extingusher, right?
The single best bootstrap method for batteries I've ever known is a direct connection to an identical battery. I.E., if you have a single charged WORKING cell to touch positive to positive, negative to negative, to each of these cells, I've seriously never seen ANYTHING that works as well.
There is also the battery restorer you can take a shot at. Costs less than this thingee you were talkng of building. A very slow charge, but really intended for lead acid batteries. 12 volt, you'd be going 3 cells at a time. (Not really RECOMMENDING this, just bringing it up.)http://www.amazon.com/BatteryMINDer-OnB ... =8-1-spell