I'm new to this forum, but my 1 mo. old CMax Energi also had a "dead" 12v battery a week ago, called Ford Roadside and the service guy siccessfully used a portable jump start unit to jump the leads under the hood, (had to use the removable little "T" key in the smart key to get into the car). Not sure, but the rotary head light switch may have been left on position 3. Then yesterday, after towing the CMax energi behind our RV for 45 minutes or so, I stopped to disconnect and watched it's main Ford-Sync display say "Power Saver - System Off", while filling a blue progress bar, and then the car was totally dead again, had to back up the RV in the middle of the road to get a set of jumper cables to reach. I called FORD's emergency number, got a case number assigned and we'll see where this goes. The car was plugged in (120v cord) overnight, it appears to have charged it's high voltage battery. Not sure about the12v though. I think the glitch has spmething to do with the "Power Saver - System Off" routine it does before going 100% dead to the owner. I wish I had checked the voltage at the actual battery terminals under the rear hatch area before jumping it and then having plugged it in overnight to charge. I did a little battery challenge test this morning, I left it's Key FOB in it, turned on it's parking lights and radio, tailgate open to the actual battery under the rear deck, and measured the battery at 12.3 v initially. After exactly 30 minutes, the car shut off the interior lights and the radio, but left the 8 parking light bulbs on. The 12 v battery had dropped to 12.05 volts. After 30 minutes longer, the battery was down to 11.8 volts, and I quit the test. By my figuring the battery was then 20-50% discharged although it had only seen maybe 15 amp/hours of use figuring running light bulbs at about 0.6 amps each. Then I plugged it's 12 v cord back in, it lite its full blue circle (Its high voltage battery was still fully charged) I think the CMax Energi does also charge its 12v battery when plugged in to 120v power as it took 0.21 kwh of power after being plugged in for an hour and a half (I have a handy little "Kill A Watt" meter it's plugged in to) and after that short time, its 12v battery then reads 14.2 volts (i.e. it's being charged). I think that calculates to it only taking 16 amp/hours to recharge, not sure how many amp hours it's 12 v battery is, since its rated in CCA vs Amp/hours, but the charge power equals the power I calculated it would have used during my challenge test. Not sure what to make of this data, I think I'm going to order a Clore JNC300XL Jump Starter for $58 from Amazon to have on hand while I wait for FORD to figure out what's wrong. The car says "Microsoft" right in the middle of the dash and you have to push a button that says "Start" in order to "Stop" your car.
