Do you have anything plugged into the OBDII reader? Mine kept going off intermittently. Fitted a switch to manually disconnect the bluetooth BDII reader which solved it.
I think you can also rewire them to get power from switched live rather than permanent but my soldering skills are rubbish.
2013 owner with 70k on the clock. 70% SOH battery.
I reckon I could do about 75 miles of motorway driving if you keep your speed under 60mph and accelerate/brake sensibly. Possibly more if yo stay off the motorway.
This sounds extremely limiting but with young kids it's rare we 5o miles...