[Jay Kickliter] built his own coin cell battery ... to see this charger project come along. Now the bad news. We looked around and indeed you can find LR2032; a rechargeable replacement for ...

His latest endeavor is a LiFePO4 battery charger that he made out of parts he had on hand for under $0.50 US. (Although we think he really made it for the fun of making it.) The circuit is ...