I have to agree with Kelmar - any status indicator, such as for battery, is only likely to drain the battery further, thus working against your goal. Disable things which are sucking up the battery and you won't need to care that much about this anymore. Besides you can see it from the settings menu and from the desk clock when plugged in.
Case in point, I've had my EVO sitting idle now for about an hour and it hasn't changed from 24% (I'm trying to get it down to like 1% and then will charge it back up fully). Read the battery life threads, there's a lot to be learned from those. I've had GREAT luck!