batteries of handheld gadgets

[adrian_turtle]

I have a Garmin GPS now, which is quite useful for finding my way on foot. I've used it a couple of times in a Zipcar, too, and it finds the satellite signal fairly quickly. Obviously, I charge it from wall power, not having a car. Because I don't use it every day (not even every week), the battery runs down when it's turned off and sitting on my shelf between uses. I'm concerned that it will be bad for the battery if I keep it plugged in all the time without draining the battery...not "bad for the battery" in the sense of causing catastrophic failure, but gradually making it less able to hold a full charge. I've been keeping it on the shelf, not plugged in, but this is not really an optimal solution. When I want to use it, the battery is usually pretty close to drained, and it takes hours to charge it. (That's what I'm doing this afternoon. Waiting for the thing to charge, and hoping it will really BE all the way charged, rather than doing that thing where it looks all the way charged and really is just 40% charged.) Any suggestions?

I'm afraid partial charging was responsible for the battery problems with my Palm (which I use as an ebook reader, mp3 player, and calender, with no phone or web connectivity.) After months of plugging it in whenever I came home, whether the battery was fully drained or 90% charged, it's only good for 80 minutes at most. 40 minutes, if I take notes. Is there a way out of this, other than carrying a charger?