High Rate of Battery Discharge - Electrical Genius needed?

[Lignumopus]

Voodoo?
Gremlins?

2006 E60 M5

• Car left locked and unused for 2 weeks.
• Then start car - fine, no messages.
• Drive car - no messages.
• Shut car down in garage - no messages.
• Attach battery tender (C-Tek).
• Check car an hour later, fully charged indication on C-Tek
• Leave C-Tek attached, quietly keeping the battery 'full'
• Leave car for a week
• Return to car, key in Igition and…….

BINGO….
I get the following……..
Indicator Message - A graphic of Vehicle Elevated on Lift
PLUS
Maintenance Message - "High Rate of Battery Discharge"

Start engine

• All systems fine
• Messages clear

NOW….I am suspicious…
I ONLY get this message AFTER I've had this C-Tek attached for a while
I am careful to attach it to the contacts in the engine bay and NOT directly to the battery.

If anyone has any thoughts/explanations/ideas/eureka thoughts to share, I would be really grateful.

Otherwise, the electrics are fine apart from the occasional spurious RESTRAINT SYSTEM FAULT in RED which my Indie checks over and clears (twice in last 6 months)

David

[contractor]

Maybe the message isn't entirely accurate?

It could be that the car is expecting a rate of discharge and because you have the thingy connected it is actually less than expected as the battery has not discharged by the expected amount? Make sense?

[Lignumopus]

contractor said:

Maybe the message isn't entirely accurate?

It could be that the car is expecting a rate of discharge and because you have the thingy connected it is actually less than expected as the battery has not discharged by the expected amount? Make sense?

Thanks….interesting lateral thoughts….
Will have to ponder that….

[TackleburyUk]

Had a similar thing on an old 535d.

Could have had a new battery that wasn't coded to the car. Or a device is draining battery faster than expected, ie it's on its way out, mine was the Bluetooth module. Or the charger is interfering with the inboard battery charging system..

I stuck a new battery in mine and the fault went, although over time the new owner (sorry!!!) would get the same and the battery would be knackered by then.

The car charges the battery accordingly depending on the age and usage. New battery not coded will be treated like an old battery for instance.

I also got this on my new f30 after parking it up and the alarm sounding when someone dented the front wing :-(

Hope this helps

[Lignumopus]

TackleburyUk said:

Had a similar thing on an old 535d.

Could have had a new battery that wasn't coded to the car. Or a device is draining battery faster than expected, ie it's on its way out, mine was the Bluetooth module. Or the charger is interfering with the inboard battery charging system..

I stuck a new battery in mine and the fault went, although over time the new owner (sorry!!!) would get the same and the battery would be knackered by then.

The car charges the battery accordingly depending on the age and usage. New battery not coded will be treated like an old battery for instance.

I also got this on my new f30 after parking it up and the alarm sounding when someone dented the front wing :-(

Hope this helps

Thank you……jigsaw pieces fitting together here…
Indie fitted new battery 6 months ago…pretty sure they would have coded it, but makes you think….

[ecain63]

On Tourers the batt discharge warning was often down to tailgate wiring issues or Ipod / media interface issues. Only issues on saloons ive known with high discharge rates are down to media interface errors of IDrive going out of whack.

As an asside, have you checked the tyre well / tool well under the boot floor for water? Also test the passenger and rear foot wells.

[Lignumopus]

ecain63 said:

On Tourers the batt discharge warning was often down to tailgate wiring issues or Ipod / media interface issues. Only issues on saloons ive known with high discharge rates are down to media interface errors of IDrive going out of whack.

As an asside, have you checked the tyre well / tool well under the boot floor for water? Also test the passenger and rear foot wells.

Gawd….no, I haven't…
Getting torch out now!
Usually better in the dark with torch looking at this sort of thing anyway!

Great advice, THANKS… :-)

[ss1977]

I had this problem with my M5 Touring and it was real pain sort out. Initially had the battery replaced as it was the original and over 5 years old, which didn't stop the error message from appearing. Then took it into BMW thinking, as an apparent electrical fault, it would be covered under the BMW Mondial Warranty. Unfortunately, it was classed as a fault caused by water ingress, which is not something covered under the terms of the warranty. Cost around £1000 to replace the various control modules. Definitely worth checking the spare tyre well for water, as Eddie has already advised, and also the drainage tubes for blockages.

However, this did not wholly resolve the problem as the error message did continue to appear, although less frequently. The fault was finally traced, by an auto-electrician, to a faulty tracker, which wasn't earthed properly and therefore drawing excessive current.

FYI, during my quest to get to the bottom of this, I found out the BMW IBS triggers the high rate of battery discharge error message once the current draw breaches 85 milliamps. The baseline draw on my car when in sleep mode was around 22-25 milliamps. A tracker at rest draws around 30 milliamps, more if the back-up battery is playing up and up to 40-140 milliamps when searching for a network. Trackers are not switched off, even if you choose not to subscribe to their services and if the car has had a number of owners, there may be more than 1 tracker in the car (heard that 1 car had 5 fitted!), each draining 30+ milliamps resulting in a current draw which breaches the IBS threshold causing the error message to ping up.

This, of course, may not be the cause of your battery discharge error message, just my experience.
HTH.

[Yellowcab]

David
How long was CTtek charger left on your car for?

[Lignumopus]

Yellowcab said:

David
How long was CTtek charger left on your car for?

Continuously…for a week.
I am suspicions of the C-Tek….for IIRC, I ONLY get this "fault" (if it is a REAL fault) displayed if the car goes "live" with the CTek connected.

What're you thinking?

Incidentally, boot and footwells bone dry….I am most fortunate, the car is virtually in perfect condition.

David

[stevesingo]

When the C-Tec is connected in battery maintain mode the battery is at 14.2v +-0.2v. As soon as you disconnect the battery voltage drops to 13-13.5 as it is no longer being supported by the C-Tec. Perhaps this is fooling the ECU(s) to think there is a drain on the battery when there is not.

I found this with the alarm on my car, which alarms when there is a voltage drop on the battery, I guess to alarm when an electrical load is sensed when the car is supposed to be locked. Connected to the charger was fine, but disconnect and within 20mins the alarm would be going off for no reason other than the battery voltaage is stabilised over time.

[BlackPorker]

I had this and it was a faulty Tracker draining the battery.