If your using the UltraFire 18650 batteries, I just found out they don't slowly die; they die a sudden death. After perusing the CandlePower forums, the consensus is those batteries suck, and most prefer the longer lasting TrustFire 18650 batteries. I ordered two on-line from a company in China, paid under nine bucks which includes shipping, and received by mail in less than a week. They work fine & dandy, and fit the UltraFire charger. http://www.bestofferbuy.com