Won't enter sleep mode (killed a battery)

lukeallison · 02-22-2022, 09:20 PM

My e87 120i is in the BMW workshop.

They said the battery has collapsed due to there being a constant current draw, when the car is off (and has been for hours) and all doors closed.

Apparently the car is never entering "sleep mode".

They want to charge thousands of dollars to remedy this issue, which seems odd for what sounds like a software fault.

Has anybody experienced this issue? How did you fix it?

lukeallison · 02-22-2022, 09:31 PM

Something worth noting is that the fan (aircon) will intermittently stop for 1 second and then keep going. It has always done this since I purchased the car a few years ago.

Maybe related?

tracer bullet · 02-22-2022, 10:41 PM

You mean it keeps going after the car is stopped? How about if you get out, close the door, lock the car, and so on?

Ahh - or it stops once in a while when the car is driving, but goes off afterwards?

I'd consider some DIY work first. It's more likely there's a hardware issue than software. There are many how-to DIY's for finding parasitic draw. Ruling out of course obvious stuff that you can see remaining on when the car should be asleep.

lukeallison · 02-22-2022, 11:52 PM

Quote:

Originally Posted by tracer bullet

You mean it keeps going after the car is stopped? How about if you get out, close the door, lock the car, and so on?

Ahh - or it stops once in a while when the car is driving, but goes off afterwards?

I'd consider some DIY work first. It's more likely there's a hardware issue than software. There are many how-to DIY's for finding parasitic draw. Ruling out of course obvious stuff that you can see remaining on when the car should be asleep.

Large current draw persists hours after the car has been turned off, fob has been removed from the ignition and doors closed.

The air conditioning fan inside the vehicle will be blowing air for 10 minutes and then pause for 1 second, and then continue blowing air. It has done this for years. I always wondered if there was a power supply issue.

Yesterday I noticed that the fan did this when the chime sounded for an error code (low tire pressure). This is after the battery was already dead and the car was only running after I jump started it. Pretty unique circumstance.

tracer bullet · 02-23-2022, 07:50 AM

Ugh, electrical issues!

1) Be 100% sure your battery is good, and replace if needed.

2) Look up how to check for parasitic draw. It includes opening the doors and hood so you can get to the fuses, taping over or otherwise fooling the sensors to think the doors are closed so the car will sleep, disconnecting the battery cable and clipping a multimeter to the cable and battery so that current can pass through it (only tiny amounts mind you, for this, not for the dome light or anything else). Then you should read something pulling and you go start pulling fuses to narrow it down.

02-22-2022, 09:20 PM	#1
lukeallison Registered 0 Rep 3 Posts Drives: BMW 1 Series Join Date: Aug 2019 Location: Brisbane, Australia iTrader: (0)	Won't enter sleep mode (killed a battery) My e87 120i is in the BMW workshop. They said the battery has collapsed due to there being a constant current draw, when the car is off (and has been for hours) and all doors closed. Apparently the car is never entering "sleep mode". They want to charge thousands of dollars to remedy this issue, which seems odd for what sounds like a software fault. Has anybody experienced this issue? How did you fix it? Last edited by lukeallison; 02-22-2022 at 11:48 PM..
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02-22-2022, 09:31 PM	#2
lukeallison Registered 0 Rep 3 Posts Drives: BMW 1 Series Join Date: Aug 2019 Location: Brisbane, Australia iTrader: (0)	Something worth noting is that the fan (aircon) will intermittently stop for 1 second and then keep going. It has always done this since I purchased the car a few years ago. Maybe related?
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02-22-2022, 10:41 PM	#3
tracer bullet Brigadier General 2410 Rep 3,546 Posts Drives: '11 135i , '15 X3 35i Join Date: May 2011 Location: Saint Paul, MN iTrader: (1)	You mean it keeps going after the car is stopped? How about if you get out, close the door, lock the car, and so on? Ahh - or it stops once in a while when the car is driving, but goes off afterwards? I'd consider some DIY work first. It's more likely there's a hardware issue than software. There are many how-to DIY's for finding parasitic draw. Ruling out of course obvious stuff that you can see remaining on when the car should be asleep.
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02-23-2022, 07:50 AM	#5
tracer bullet Brigadier General 2410 Rep 3,546 Posts Drives: '11 135i , '15 X3 35i Join Date: May 2011 Location: Saint Paul, MN iTrader: (1)	Ugh, electrical issues! 1) Be 100% sure your battery is good, and replace if needed. 2) Look up how to check for parasitic draw. It includes opening the doors and hood so you can get to the fuses, taping over or otherwise fooling the sensors to think the doors are closed so the car will sleep, disconnecting the battery cable and clipping a multimeter to the cable and battery so that current can pass through it (only tiny amounts mind you, for this, not for the dome light or anything else). Then you should read something pulling and you go start pulling fuses to narrow it down.
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