His latest endeavor is a LiFePO4 battery charger that he made out of parts ... the transistor acts as a closed switch, sinking around 100 mA of current to ground. If you tie the reference pin ...

It was a 31-series 100-amp-hour, 12-volt deep-cycle battery featuring lithium-iron-phosphate (LiFePO4) chemistry ($899.99 ... the battery in conjunction with the ­X2Power 7.5-amp battery charger ($129 ...

Because lithium batteries can recharge in much less time than lead-acid batteries, a short run of an engine’s alternator integrated with a DC-to-DC charger can quickly bring them to full power.