No indication as to whether it's on or off unless you flip open the lid. No way to turn it on or off unless the vehicle is on - mine has inadvertently been left on for this very reason . . . Again, with no readily apparent indicator.
I use mine a lot! It is a nice convenience. It could, however, have been better executed. With a Minnesota winter rapidly approaching, it will be interesting to explore the functionality of the unit in cold temperatures!
I added a drop in tray for additional storage which, then, limits the height of items in the cool box to that of a standard, 12-ounce can. Works for me. YMMV.