Better Battery Meter

I went to the Jacksonville Sea & Sky Spectacular today and did some shooting. I made over 300 exposures and was using the tracking version of autofocus to drive a 300 and 80-200 lens most of the time. It's rare that I pull that much juice from the batteries but they lasted the day which I was quite happy about. I'd like to see a better battery meter in the camera though to get a better idea of how much juice I have left. The meter on my camera has just three readings it can show: Full charge, partial charge and basically dead. I'm not sure at what point the camera decides to move from full to partial, it seemed to make that jump about 1/3 of the way through the day. This made me quite nervous since I wasn't sure if that meant that I only had 1/2 of a charge left. I slowed down on the shooting at that point and did a lot more manual focusing to try to save the battery. I'd like to see a meter that gives you an estimation of the percentage left to, say, the nearest ten. This would make it a lot easier to pace the shooting to make sure you can last as long as you need if you don't have spare batteries with you.