...a new battery makes. I've had an IBM Thinkpad X21 for nearly two years and have seen no reason to upgrade (a change from when I was at IBM and regularly changed Thinkpads yearly, I think partly due to abuse). One problem I've had is that the original battery lost 50% of its capacity to hold a charge (it's rated for 40 Watt hours, was holding 18). Complicating things was that the battery indicators on the system don't really warn you that a 100% charge is 100% of whatever the current capacity is, not the original capacity. Sealing the fate of my old battery...I tried to cycle the battery as recommended by the IBM online help. This process implies that you might get more life out of the battery. The reality is that it seemed to be the last shove over the edge. I did that about a week ago and the battery dropped from holding about 90 minutes of charge to 30 minutes of charge. Again, all the while the battery gauge happily reported 100% (or 97%) charge available. I gave up and bought a new battery and am back to having nearly four-five hours of charge time.