Hi,
just changed my battery for one of these this evening
Buy iRiver H110, H120, H140, H320, H340 Extended Battery at GPS For Less Limited (only £12.98 and it comes with a tool like the ones in the dismantling instructions post)) (it says its for a H110 but it fits) its a 2200mAh battery so I`m hoping my H10 will last longer now, the old battery was lasting less than 2 hours.
Its not too difficult change the battery using the instructions (provided you have a small amount of technical know how)at the link posted earlier. I didn`t dismantle the H10 as much as it tells you in the instructions just enough to get at the battery. I could not get the back off so I had to use the wriggle and pull method, as mentioned in one of the posts after the instructions, which works but a word of warning these batteries are very soft apart from the edges and its easy to squash and bend them. In fact by the time I found this out I had no choice but to change it as the original one got a bit mashed. It all worked fine when I put it back together and the new battery is charging now. Will update new battery life once tested it out.