Lock Car to avoid Battery Drain

[jammit]

Picked-up a MY10 a few days ago and the SA told me they advise all owners to lock their vehicle overnight (even when in locked garage) to avoid battery drain in case the car is not used for a few days.

I am very surprised at this advice and asked exactly what drains the battery if I don't lock the vehicle. Didn't get a clear answer.

Has anyone else come across this advise? Does it make sense?

[eyeguy]

Search for X5 battery drain issues and you will find a slew of threads. Yes, this has been mentioned before - when unlocked, the car will periodically go thru readiness checks - sit in your car sometime in silence with it off and unlocked and you'll be surprised to find how often it "comes to life" with various clicks and whirs - I can easily see how this would drain a battery over time especially when it isn't driven often or for long distances to sufficiently recharge. Locking the car supposedly "puts it to sleep" - i.e. no readiness checks until you unlock. I live in Wisconsin and have NEVER had the battery warning - even in the dead of winter - and I drive only 3.5 miles to and from work many days. I attribute this to locking it every night. FWIW

[killcrap]

locking has no effect on the cars battery performance. sub-urban legend...

What happens overtime when you dont lock your car, is that the car goes to a deep sleep mode. In which, when the next time the vehicle is woken up, some K-Can subscribers do not wakeup completely and communcate to the BUS, and when there is a delay such as this, it registers it as a fault in the energy histogram saying, one or more k-can subscribers failed to participate in the energy diagnosis. This causing a false battery discharge warning. In order to correct this on e70 vehicles, you must perform an energy diagnosis, and clear the fault memory. Drive the vehicle approx 1 mile, and park and lock the car. Wait 16 minutes, and then the battery discharge check control will no longer be on.

[X-cellent]

Originally Posted by killcrap

locking has no effect on the cars battery performance. sub-urban legend...

What happens overtime when you dont lock your car, is that the car goes to a deep sleep mode. In which, when the next time the vehicle is woken up, some K-Can subscribers do not wakeup completely and communcate to the BUS, and when there is a delay such as this, it registers it as a fault in the energy histogram saying, one or more k-can subscribers failed to participate in the energy diagnosis. This causing a false battery discharge warning. In order to correct this on e70 vehicles, you must perform an energy diagnosis, and clear the fault memory. Drive the vehicle approx 1 mile, and park and lock the car. Wait 16 minutes, and then the battery discharge check control will no longer be on.

While I won't refute the above, I can assure you that battery draining on these cars EVEN WHEN LOCKED ALL THE TIME is a known issue, and have personally had three instances where-in my 2008 4.8 has had a dead battery for no apparent reason....(i do have comfort access which seems to play into this).

Locking seems to help (my SAV sits outside so it is always locked), but is not a fool proof solution as mine has told the dealer; "my door was opened too many times today without me being started (car was being vacuumed after being washed), I am not being driven long enough each day (normally 8 miles each way to work @ 55mph - and on the week of failure 100mile plus round trips each day), and someone left my tailgate open for 20 minutes (which apparently is WAY too long for the car)).....

My busness partner drives his 2 miles per day (8,000 at 1.5 years old) and has not had an issue...but he does not have C/A. It seems impossible to figure out why so many have had issues.....

[jammit]

It sounds like there are potentially a number of reasons for inexplicable flat batteries or false battery discharge warnings.

Locking the vehicle in my locked garage at night is a pain. On balance do people recommend I go ahead and start locking it to preserve battery? Seems a design flaw to me.....

Also - is there any way of programming the vehicle to self-lock after a period of time - say an hour? I understand the risk of locked keys, but think I would still use this if available.