Exactly, same question … where do you buy the battery? The guide to carefully opening the TomTom gps runner watch is excellent, especially with the right tools. Now, all I need to know is where to buy the replacement battery. The dead battery is wireless, 2 thin metal strips designating + and - also this is its serial number SP332230 ABL S45 28 N60323. I assume the first series of digits SP332230 is key serial number.