also, have u "re-trained" the phone's battery stats? after my first flash from eclair my battery was rubbish, but then after a 'reset' it was perfect.
by 'retrain'/'reset', what im talking about is, use phone until totally dead (turns off by itself), remove battery for 60sec, replace and charge to full while off, remove battery for 60sec, replace and reboot.
i dont know if there is any science to that voodoo or if the equivalent of that is just wiping battery stats using something like CWM recovery, but i did it the discharge-remove-recharge-remove method twice now and success each time. so i cant help but suggest you try it.