Does anyone know if the cigarette lighter plug would take a charge if the car was turned off.

Meaning, if I leave the car locked and one of these running...

http://amzn.com/B00G6C5NR6

Will it keep my battery from draining and dying?

 

The cigarette plug isn't hard tied to the battery (a.k.a. hot/always on). If it was, it would work, but you would have to keep the ignition on accessory for it to work through the cigarette plug.

Also, that device provides less than 1A. It would hardly be enough to overcome something draining enough to kill a battery. I don't think it could really even run a laptop.

 

You'd need to instal a plug-in connector (like a Hybrid!) and wire it into that.

On a sunny day, it will overcome the alarm system, which is the usual culprit.

I have one I used to use on the Prelude.

But the lack any discernible sun here meant it was one of those purchases made rashly.

If it wasn't a tad impractical, you'd be welcome to mine!

 

On a side note, I've always wondered how much power that green LED (to indicate interior lights on with doors open) uses up. My RL often sits for several days at a time in the garage.

 

Max current on a small LED like that is 20 mA. Assume a 2V drop, and you are looking at 40 mW or IOW nothing.