The 12v battery gets less and less capacity as it gets older. Meaning you can turn on your lights (for example) for a shorter amount of time before it browns out. Can't turn on headlights by the way with the car off, but just parking lights. So maybe a new battery the parking lights will run for an hour or 2 before the battery is drained, with an older battery it might be 15 minutes maybe 1/2 hour. I don't know the exact numbers, I haven't tested it, but you get the idea.
If the car is plugged in, when you open the door the lights come on, and the charger kicks in and supplies power (starts blinking if it was completed already and not blinking). If its not then its all on the battery.
My battery is 4 years old now and logic dictates that it doesn't last as long as a new battery. Not wanting to risk it being damaged while I'm gone on vacation, I jumped it with a 12v deep cycle battery while I was gone for almost a month to FL and Jamaica in March. If I left it and the battery died, the low voltage would damage the battery and it might be finished off from being dead while I'm gone. But the fact that it didn't I will get more life out of it.
So far as for the tires I'm up to 72k miles with them, they will probably go to 80k miles before they reach the wear limit bars. We'll see how they fare out this summer going to Indiana, Delaware and new Brunswick.
As far as the 12v battery goes, I've been known to keep car batteries for close to 10 years in my old Mercedes that I had since 1992 (to 2013) when I traded it in for the Cmax in 2013. We'll see how long the Cmax battery will last, but as it gets older and older I will make sure I jump it before going on vacation to protect it from dying. Its either that or disconnect it completely, but jumping is easier.
Anyway the car says its "sleeping" and cannot be woken up until physically accessed according to MFM after about a week of inactivity. Ford did put in some sort of battery protection level to minimize the drain on the 12v battery.
Edited by rbort, 01 June 2017 - 08:54 AM.