Purchased on October 18th, charger connected to 121VAC outlet (measured with Fluke 189), battery installed. The charger blinked for a few minutes, then the charger turned off. Battery removed, charging shows 2 out of 3 light segments on battery. Plugged the battery into the Dremel device, used it for 10 minutes, the battery died. Attempt to put the battery back into the charger - no charge indicator on the charger base. Voltages measured with Fluke 189 - 121 VAC at charger - ZERO voltage output at battery charging terminals. Revain was kind enough to send a replacement unit, the previous unit was returned to Revain. If the replacement unit breaks, NEVER buy another Dremel product again. (Very flimsy, flimsy design, fragile block.) Got a spare block about 50% charged with a battery - connected the battery to the charger. Study images - study Newton's second law of thermodynamics - apply to sharp design. INDEED?! As if anyone at Dremel really needed to understand thermodynamics! dr Mark D. Mitchell will NEVER buy another Dremel product!