I'd like to add an LTE router to my vehicle. I'm a traveling salesman, and I'm frequently starting/stopping the vehicle, but also don't drive it every day.
I'd like to find some kind of solution that won't power cycle the router every time I turn the car on/off.
I thought about just wiring it to a small SLA or Lithium battery, then use an automatic relay to charge the lithium battery when the engine is started. The problem, then, is to keep the router from completely draining the router's "house" battery when I don't drive the vehicle for a couple days. The best I could come up with is making some kind of shutdown script if no traffic passes through the LAN for X hours. Of course, then I'd have to find a way to power it back on when I start the car the next time....