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I know some of the systems stay on when the car is idle, but I can't seem to find a good list. Assuming a fully loaded smart, with all the options in their most power consuming mode, what stays on when the engine is off and the driver walks away?

Right now from most of the posts I've read (in this forum and others), the following is the short list:

  • Anti-theft/alarm system
  • Stereo system (should be minimal draw though)
  • Auto wiper / Auto lights system (more in 2009, but 2008 does too?)
  • Heated rear-view mirrors
I'm mainly asking because I'm trying to track down what could be causing my '08 to drain it's battery over a long time period. I'm finding that on Mondays after a "lazy weekend" of no trips, it has power issues which seem to clear up during/after the work commute(s). (Power issues being things like flickering head lights during shifts, radio asking for protection password on starting the car, etc.)

I'm hoping to put a switch in for the mirror heaters soon, since 70% of the time it's inside a garage, but I'm just wondering what else could be causing a drain on the system. :confused:
 

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The best way would be to put a meter from the disconnected negitive cable and the battery terminal and then pull fuses and look for a drop in current drawn. As for the mirrors all you have to do is pull the fuse under the dash - it is on its own circuit. I have not had any issues with mine, dimming lights etc. There have been some bad batteries out there and loose grounds by the battery. This might cause that. I would get the battery load tested.
 

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Lots of stuff on modern day cars stay "ON" but they aren't really on, just hooked up to power via a switch or sensor (like headlights, interior illumination lights, some assessory power outlets). I don't think your wipers will work till the ignition is on. I doubt they will activate if it rains on your turned off parked car.
However, some things are always "ON" in that they draw power even when the ignition is "OFF". Anything that requires to keep data in memory will have a draw. For example, the car's computer (or ECU) draws power all the time. Also the radio will draw power to keep track of your pre-set radio stations and other setting. Most anti-theft radios need power to hold the code. An alarm system is also a draw when on standby to be armed and when armed, it draws a bit more power.
 
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