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In an episode of "Breaking Bad" I saw last night, a key is left, unturned, in an ignition lock (as a handy place to keep it) for about 48 hours, resulting in a flat battery. How is that possible?
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Keys now have micro chips to communicate with the car's security system. I suppose that must have caused the battery drain.
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Some batteries within the keyfob also are charged by induction, although I can't see that running flat a car battery.
Depending how old the car was, leaving the key in the ignition could have resulted in the CanBus system not shutting down.
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Suspect it isn't, although one could design an ignition lock to power some ancillaries on insertion of key rather than tuning a key to position 1. (The old fashioned and perfectly adequate way of doing it).
If the security system can flatten the battery in 48 hours - it's not very good, or the battery was not well charged in the first place.
Last edited by: Slidingpillar on Wed 5 Feb 14 at 13:30
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ISTR that, on my son's old Corsa, there was a button at the bottom of the barrel which allowed power to the radio when the key was inserted.
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Quite possible
Previous Passat (Y reg and in warranty at the time) had flat battery one morning, AA turn up and got it going then tried to find out why (no lights left on, even checked boot and glove box).
His ammeter was showing a battery current of 1.8A with key out, car locked and everything off - including him pressing the bonnet switch so the alarm thought the bonnet was closed. Call to HQ confirmed that "everything off" current was 1.8-2A.
So it can happen, surprised it doesn't happen more often.
The Octavia made all sorts of noises after you took the key out, SWMBO didn't like sitting in it without the key in as she felt the car was alive. I guess the current Passat will act in the same way.
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On a key-less entry Micra, ignition off, (long time ago now) I measured the current drain, both when the key was a long way away and then when it got close to the car. The current drain went up a few times when close. IIRC it was still only 0.065 amps with key close.
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Battery drain via ignition lock? - Robin O'Reliant
