Has this been invented? And if not, why not?
We have a second car that we drive rarely. When it's this cold, we really should start it more often and let it run. This week we were reminded of this again--the hard way. My wife needed to use this car on Tuesday. It started fine and she drove to our son's preschool--about a 10 minute drive. When she came back out, the car wouldn't start. The AAA guy told her/reminded her that starting the car takes the most charge off the battery, and he suggested starting the car every other day at least and letting it run 15 minutes at least each time.
So this morning while my wife and children were all out, I spent 20 minutes of quality time with the New York Times Book Review and the sounds of Sinatra on 1320 am and sat in the car with it running. But while I sat, I thought, and this is what I thought: the AAA guy has a tester that tests the charge. Why not have something like that always testing the charge with a wire running to a dashboard control that displays how much charge is left or how much time is needed to recharge the battery. That way, if you don't use the car much, you can check out the "battery monitor" when you do get the car started and if it looks low (maybe bars like on the cell phone?), you can bear this in mind if you're making a short trip and make sure to let the car sit and idle for a while. Seems like it would be a useful feature. So why isn't there something like this on car dashboards?
Unless--this is a scary thought--we are part of a very small minority that lives in a cold climate with a (second) car that is used rarely and only for short trips. So maybe there's no market?