I have a 2nd gen Fit and one time I forgot to turn my headlights off after driving. Luckily i caught it after an hour or so and it started the car fine.
But I'm curious about what would happen if it was left overnight. Does the Fit have a battery voltage monitor built in of some soft? Is there any aftermarket devices out there that can automatically disconnect in such a situation?

 

There's nothing to automatically turn the headlights off. On at least the later model years of the 2nd generation, the dome light and cargo light will turn themselves off after awhile if you leave the door or hatch open, but not the headlights. If you leave them on overnight, you get a discharged battery (and fully discharging a lead acid battery is quite rough on it, so you may also have a battery that needs or soon needs replacement).

It certainly would be possible to construct a low-voltage battery disconnect, but to do so well would be a little tricky. You would need a disconnect that can handle a pretty substantial current, and yet doesn't require any significant current itself in either the on or the off position, so an ordinary relay would not work well. You'd also probably want to separate out the circuits that get disconnected from those that presumably shouldn't (such as the radio clock and remote door lock circuits), and have some means of bypassing it to start the car when you return to it to start it again. It would most likely be a good bit easier to retrofit a headlight turn-off timer, all told, or even an automatic headlight system.

(Is your headlight on beeper not working properly, or did you intend to leave them on and then forget afterwards?)

 

i was wondering this too...

 

No the headlight beeper was working but I wasn't aware of it at that time. I used to drive a Camry and its headlights turn off automatically so I never thought about it.

I've learned to pay attention to the beeper from now on though so that it won't happen again.

 

sounds good, lessons learned. did you know that the e-brake also beeps if you have it pulled and you drive?

 

Yeah I also did that once and the beeper and brake indicator both came on to let me know.

Went to the dealership today to get the VSA updated and it took 2 hours. Didn't think the process would take that long but everything's good now.