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Old 08-20-2011, 06:08 PM
Supercourse Supercourse is offline
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Location: British Columbia, Canada
Join Date: Feb 2008
Posts: 3,890
Mein Auto: 2004 X3 2.5i
Originally Posted by timfitz63 View Post
The computer (ECU) of most modern vehicles uses the 'door lock' command to put the vehicle into 'sleep' mode. So it's generally a good practice to lock the doors, even inside your own garage, and particularly if you know the vehicle will sit for a while.

...... but devices like security systems need power to perform their assigned functions, so over time, they will discharge the battery if the battery is not replenished by driving the vehicle, or using a trickle charger.
Interesting point.

For the X3, I was thinking that when left unlocked, the sleep system does activate but only after some period of time (not a clear cut interval, but maybe 20 mins. or so, similar to the timeout for the radio).

At that point, the only noticeable thing drawing power is the little orange light for the A/T shift position. (Not sure of the purpose of that staying on.)

If something like the overhead light had been left on, this seems to get turned off when the sleep system takes over (but will go back on again next restart).

If you lock the doors, the sleep system might activate immediately, that A/T light goes out, and the clown nose starts flashing.

In my case, with no options, and no electronic accessories, battery depletion when sitting either locked or unlocked for a week or more hasn't been an issue.

So I would surmise that the current draw from the clown's nose (and immobilizer) is not much different from that for the little A/T light.

Cigarette lighter outlets are outside the sleep system control, allowing a battery tender/minder to be connected there if you choose.
(Seems to be a European thing for always live outlets, Asian and domestic makes favor ignition-switched outlets.)
But that means, of course, that some other personal entertainment/productivity devices left unwittingly on can drain the battery.

I don't think that locking the X3 turns those 12V outlets off.
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