I've had a Spot GPS for the last year, but sold it once the re-subscribe bill came around. I never used it to send OK messages, and only carried it for emergencies. A PLB made much more sense for me. So I bought this little guy, and it came in the mail today. The first thing I did after taking it out of the box was to place it in a protective pouch and store it safely for my next trip. WRONG! Since the moment I ordered it I was intrigued by the $150 battery replacement cost. It reminded me of some of the Apple products I've owned, where the battery replacement cost is easily 10X the price of the battery itself. Well, this turned out to be the same case. Two simple philips-head screws later, the battery was revealed. It's an extremely basic 9v LiMnO2 battery pack. You can either buy the pack pre-built or buy the individual cells (they're made by Panasonic) and solder one up yourself for even cheaper. I look forward to replacing my battery pack for cheap when the time comes!