If you charge it during off state and it straight away go green, it is at full capacity. Anyways, if you want a more detailed report on how your battery is faring, go to the Market and look for 'OS Monitor'. If you go to the 'Misc' tab you'll see some info about the battery. If you see 4000mV and you're around 90% capacity or more. Then the battery is fine, generally speaking.

Here's the good part though, something that can measure whether bump charging will have any effect on your batt. Go to the 'Message' tab and click the 'menu' button on your phone. Choose 'Option' from the pop-up menu and scroll down until you see the 'Message' section. In the 'View Log' option choose 'dmesg'. Tap 'Filter dmesg', check 'Enable Filtering', tap 'Tag Filter' and type 'batt' in the text box. Get out from the 'Options' (press 'back' a couple of times) to the 'Message' tab. You'll now see a more detailed stats of the battery condition, including the rate of it discharging. Apply some common sense here, a Desire/Nexus battery is 1400mA (it's actually more but HTC rounds the figure). So if your condition is at 100% and you see the reading is below 1400mAh (like 1300mAh or something worse), then you'll need to bump charge it and reset the battery stats as it is obviously giving the wrong reading. Some guys on XDA managed to get it up to 1480mAh through bump charging. That mAh is actually an indicator on how much juice your battery has. The more, the better.