Today for the first time my T600 suddenly started beeping the low battery warning to tell me it was down to 18%, but I had recharged it fully overnight and had hardly used it today. I have now had it recharging with the synch cable since the afternoon (about 3 hours) and it seems to be stuck at 46%. Is it time for yet another replacement? If so, has anyone had luck getting the Sprint store to give you a 650 replacement instead??