I'm not sure about the phone being powered on or off while re-charging during this re-calibration process.
There are apps in the market that pretty much do the same thing as the CWM wipe battery stats function,though,the apps may have more detailed information on the subject.I've also observed that the battery indicating can show a drastic drop at both ends of the charge spectrum.(FULL CHARGE & LOW BATTERY Conditions)
There is a thread floating around A/F (somewhere) covering all the battery stats/calibration/charging/indicating issues.
Again,GOOGLE is your friend on this issue.You might also want to look up 'Bump charging' when researching the subject.
Yeah, google is usually the first thing i hit.. And on that, from my reading, I don't believe it has to be off for the recharge.. Only when bump charging.. And for all else interested, found this excellent article on that on PPA..
PrepaidAndroids.net - CONTRACTS SUCK!
Edit: I thought this app was mentioned in the article but maybe i missed it looking through again.. An app to simplify is called BatteryCalibration.. is on the market..
Edit Edit: well, tried the bump charge on it (maybe i didnt do it right) and still shot to 93 within a few minutes.. already reset battery stats when it was at 100 so going to finish that process off and see how it goes.. will keep posted..