Investigate scheduled departure

[shreddedbacon]

If using the controller to provide an API to a TWC, if you use scheduled departure, the car can sometimes get into a funky state where it will not charge.

The car sees 0/0A available to it and says there is a problem with the power source.

This might be related to the heartbeat that gets sent to the TWC every few seconds. I've recently added a default value that gets sent in the heartbeat, which should always send the available amperage to the TWC so that scheduled departure knows that it can charge.

Need to keep an eye on this, and actually test it myself.