Wanted: BMW Electrician, West London

[madou]

Your challenge: E39 540iA Sport Touring 2001, intermittent currency drain, hard to track down, which kills the new battery in 2-3 days. Needs to be fixed in the next week

[Mustard]

Long shot, but you arnt keeping anything metal in the load compartment side lockers are you?

[madou]

Mustard said:

Long shot, but you arnt keeping anything metal in the load compartment side lockers are you?

No, car is empty, but thank you for the idea

[dandrus]

off the top of my head and a fault i,ve come across befor is the metal contacts in the boot that control the int light. they get corroded and the pins get stuck so it might be worth avin a little look.

[madou]

dandrus said:

off the top of my head and a fault i,ve come across befor is the metal contacts in the boot that control the int light. they get corroded and the pins get stuck so it might be worth avin a little look.

Good idea, but the problem here is that this is a fault which doesn't show if you connect a multi meter for a few hours with a "snapshot" approach to finding the drain, and yet is enough of a drain that the new battery only shows c. 5.5v after 2 or 3 days of the car standing idle, which means that it must a considerable drain given the 120Ah ( exact size ? ) battery in the boot of the 540i

[fixedwheelnut]

Top causes for battery drain on E39's are Heater fan resistor pack[hedgehog] causing the fan to run intermittantly.
And the Electric cooling fan at the radiator, it can draw current without spinning the fan.

[phelix]

And you're confident the battery's actually OK?

[Vee]

phelix said:

And you're confident the battery's actually OK?

madou 2 posts ago said:

yet is enough of a drain that the new battery only shows c. 5.5v after 2 or 3 days of the car standing idle, which means that it must a considerable drain given the 120Ah ( exact size ? ) battery in the boot of the 540i

[phelix]

Vee said:

phelix said:

And you're confident the battery's actually OK?

madou 2 posts ago said:

yet is enough of a drain that the new battery only shows c. 5.5v after 2 or 3 days of the car standing idle, which means that it must a considerable drain given the 120Ah ( exact size ? ) battery in the boot of the 540i

Yes, thank you; I too can read. It's not unknown for the odd new battery to be duff and unable to hold a charge. Hence my wording...

[madou]

Vee said:

phelix said:

And you're confident the battery's actually OK?

madou 2 posts ago said:

yet is enough of a drain that the new battery only shows c. 5.5v after 2 or 3 days of the car standing idle, which means that it must a considerable drain given the 120Ah ( exact size ? ) battery in the boot of the 540i

Point taken about checking the battery. Chief suspect is the dealer fit traffic master module, which was switching itself on, and draining c. 1 Amp Hour

Traffic master module has now been isolated, problem has not reoccurred, thank you all for your advice

Edited by madou on Monday 19th November 12:08

[phelix]

Glad it's sorted but you may wish to appraoch the dealer about replacing the battery at their expense. Car batteries do not like being deep discharged; it shortens their life considerably.

And to Vee: if my response came across as too sarcastic I apologise; that wasn't my intent.