The Tesla app in my smartphone has not been able to consistently communicate with my car. Sometimes, it just won't connect, so I can't heat up either the passenger compartment or the battery in advance of driving. With the temperatures dropping lately to single digits (F) where I live (in February 2015), I'd sure like to be able to turn on battery heating before I start to drive the car (for reasons that are discussed elsewhere in TMC). So, I called the Tesla Service hotline. While the technician was helping me diagnose the problem with the inconsistent communication between my smartphone and the car, I asked him if he knew of a way to turn on the battery heating w/o the app. He said yes. To turn on battery heating without the app, just increase the battery charging limit temporarily; e.g., if the limit is normally set to 80%, increase it to 90% to start the battery charging. While the battery is charging, it is always also being heated. Once the 90% is reached, both the charging and battery heating are automatically stopped.