Originally Posted by EllyEnthusiastic
edit: Forgot to mention, the batteries are fine, they fully charge, I've metered them and their voltage is fine-- better than, actually. They're rated 3.7V, but one came out at 4.17V.
After my laser died, I got my batteries tested too and got the exact same results. I had them tested at an electronics store. Right away after I heard about the voltage being higher than specified, I figured the higher voltage probably fried my laser's diode, but the technician told me that a higher voltage reading is actually normal. He said that anything below 3.7v is considered "dead" on a 3.7v battery, and that they should be closer to 4.1 or 4.2v when charged. That kind of surprised me since regular AA batteries are 1.5v, yet rechargeable AA batteries are only 1.2v, and they aren't "dead" at all.