As others have mentioned, your battery is likely on the way out if it isn't lasting 10 minutes.
I'd have turned the engine off too if waiting over a minute, but I also would turn the headlights off, leaving just the parking lights on. Blower motors are also consume a lot of electricity, so that should be turned off as well.
You should get a cigarette lighter charger for your phone. Even better, get one of those cheap batteries that can charge your phone several times and include a light.
Amazon link
...and I'm curious, was your friend a girl? You need a friend as loyal and helpful as yourself.