Firstly, a big thanks to the posters and mods on this forum. I managed to root my phone and apply CM7.1 without having to ask any questions on here and was able to do it simply by reading all the advice given here, especially by El Presidente and D-U-R-X. You guys have the patience of saints! However, now that I have caught the bug, I do have a few questions about battery calibration and applying ROMs. Firstly, just to be sure I'm right on this, using the apps CurrentWidget and Battery Calibration, is it correct that a full calibration after a ROM installation requires one full charge until the phone is drawing 0mAh from the charger, then a wiping of the stats via Battery Calibration, followed by a full discharge until the phone switches itself off? Is this enough or should this be followed by another full charge from zero to 100% to ensure the full battery capacity range has been captured? What happens if you switch the phone off or carry out a reboot before the first full discharge, do you have to start again? Secondly, if you want to try a new ROM, when you backup your current ROM, I assume the backup includes the battery stats, so that if you return to your backup there is no need to recalibrate the battery? If this is the case, then I assume that you should finish the calibration cycle before trying a new ROM, due to the battery stats change that will have taken place in the meantime (or start again after restoring a backup)? Obviously, if you stick with your new ROM a fresh calibration is required. Finally, what exactly is the Dalvik cache? From what I've read and been told it is separate to any backups and should be wiped after any new ROM or return to a backup ROM, is this correct? Does the Dalvik cache contain any of the battery information and therefore going back to backed up ROM means that a fresh battery calibration is required, since you will have wiped the cache? I love my DHD, it's the best phone I've ever had, but I hate that it can't even do 24 hrs without a fresh charge, except if you just keep it in your pocket and only make and receive the occasional phone call. As soon as you use something like GPS for an hour or so, the battery plughole opens gapingly wide. So, as one of my main reasons for rooting and applying new ROMs is to improve battery life, like for many other people, but also seeing what new ROMs look like, these are important questions to me. I love the way you can simply return to a previous ROM so easily after trying a new one, but if doing so keeps messing with the battery stats, then it should be avoided, as I don't want to be tied down for several hours just to ensdure that the battery stats are correct. Or am I worrying needlessly?