Update to my previous post: I use my CB pretty steadily, so it doesn't sit idle for very long. My impression was that there was very little battery drain while powered on, but in sleep mode. I decided to force myself to take a break from it yesterday and measure the battery drain. The result: In 16 hours of sleep mode, the battery dropped from 100% to 94%. So, it isn't as small a drain as I thought...about 9% a day, if one can reliably extrapolate it out that far. Normally, if I weren't going to use it for more than a day, I would power it off anyway.