Mark, I wouldn¹t expect the CAC to change during a charge, even if your firmware is querying for new values during that time. I¹m only seeing the CAC change about 10 minutes after a charge, or drive, and not every time. My CAC changes pretty often when I do a drive/charge cycle: sometimes after the drive, sometimes after the charge, sometimes both, occasionally neither. Perhaps the v2.x Roadsters have a different CAC calculation that¹s less volatile than the v1.5 Roadsters. I¹d be interested to hear from other v2.x Roadster owners about how their CAC values change. If anyone is interested, I can share my custom firmware that records info on when the CAC changes. Send me a private message if you¹d like to geek out on CAC values. Tell me your hardware version and time zone offset, as I have to do a special build for each time zone so I can convert from GMT to local time correctly. Tom From: Mark Webb-Johnson <mark@webb-johnson.net> Reply-To: OVMS Developers <ovmsdev@lists.teslaclub.hk> Date: Fri, 12 Apr 2013 09:04:08 +0800 To: OVMS Developers <ovmsdev@lists.teslaclub.hk> Subject: Re: [Ovmsdev] Release Firmware Tom, I'm not seeing any change to my CAC, for the past few weeks. It has kept stable at 156.94. <snip charge records> It has got me a little worried, thinking perhaps that there is something else that 'triggers' the CAC recalculation (perhaps in the DIAG screens). Regards, Mark.