The batteries were brand-new lithium batteries, not the rechargeable kind. I read the directions very, very carefully (I had them with me on the trip). I was not getting the "low battery" signal (blinking red light) but the "not fully treated" signal (steady red light coming on during the cycle). My son tried the Steripen also and was less than pleased.

Just the fact that it's extremely difficult to turn on and off is one of the big reasons I have troubles with the Steripen Adventurer. You guys undoubtedly all have stronger hands than I do!

As I said, Your Mileage May Vary. For me, it's back to the gravity filter!