Escalade EXT Dead Battery

My wife drives a 2007 Escalade EXT, same as the Avalanche. Every once in a while, maybe 1-2 months, she’ll be greeted by a completely dead battery. Nothing has been left turned on electrically. At one time it took only 30 minutes after shut off for the vehicle not to start. The battery load tests fine. Usually it can sit for days and start fine. Any thoughts what might be happening?

And for those who’d like to criticize the needless excess of this vehicle, please don’t: it has brilliant flexibility in its capacity, gets 20 mpg highway, all time awd, and ride and luxury to die for. I used to criticize these as needless excess until I sat in one- in the rear seat, no less…

At any rate, I digress. Thanks for any input.

A battery that age could be dying a natural death, but I suspect something else.

  • Check both ends of each battery cable. Make sure they are clean and tight. Have you checked the electrolyte level?

  • Nothing has been left turned on electrically Are you really sure of that? Modern cars have lots of electronic devices that function when the car is turned off. A prime villain are aftermarket security systems, and sometimes OEM security systems.