Were daytime running lights on? 10A draw right there. Radio draws another 10A. Heater fan, maybe 15A. We're up to 35A. Was the heater dial on Defrost? A lot of newer cars assume that the owner is a f**king idiot, and turn on the A/C for you when the heater is set to Defrost, meaning that the radiator fan would be running. Another 25A.

60 amps for 45 min would do a healthy job of killing a battery.