Mystery Electrical Drain E39 530D Touring 2002

[Pork_n_Beem]

Had trouble with flat battery even though i use the car daily, thought battery must be duff (was the original) so replaced it, after about two weeks flat again, very odd.

Thought i would put an ammeter in series with battery and lock the car.

The ammeter was all over the place going from 0.5amp to 5 amps randomly. I thought it must be the alternator so i disconnected it and the amps stabilised at 0.5amps but when i reconnected the alternator is was still just shoiwng 0.5amps which should take 200 hours to flatten the battery not like 12hrs.

I am at a loss - is this a known problem on these cars as they get older ?
Any ideas gratefully received

[Fox-]

Had any problems with your climate control lately? This sounds like it might be the final stage resistor which controls the blower etc. It has a mind of its own when it fails and will do things like turn your blower on at 2am and flatten your battery.

[gizlaroc]

Also have you got traffic master fitted, these pull .5 amps and when a battery gets old that is enough to knock it out.

Once you have had a flat in the cold you need a new battery.

Also aftermarket phone kits pull around .5 amps if wired incorrectly.

[andye30m3]

My M3 evo was doing this but worse, would drain a battery in a couple of hours,

Turned out to be the heated rear screen staying on, due to a problem with the heater control in the dash.

Can also be the light in the boot staying on due to a duff switch.

[rassi]

Fox- said:

Had any problems with your climate control lately? This sounds like it might be the final stage resistor which controls the blower etc. It has a mind of its own when it fails and will do things like turn your blower on at 2am and flatten your battery.

+1 This may very well be your problem, and is very easy to DIY: http://www.bimmerfest.com/forums/showthread.php?t=... or http://www.540i6.com/finalstagereplacement.html

Could also be a Trafficmaster or aftermarket alarm, if installed?

[noumenon]

Does it have a tracker? These have rechargable batteries which should offset the drain, but of course, batteries do fail.

[BikealarmBlair]

noumenon said:

Does it have a tracker? These have rechargable batteries which should offset the drain, but of course, batteries do fail.

a tracker (unless faulty) will draw less than 10mA back up battery is just that a back up incase the power is removed its not to run the system.

[BikealarmBlair]

Pork_n_Beem said:

The ammeter was all over the place going from 0.5amp to 5 amps randomly. I thought it must be the alternator so i disconnected it and the amps stabilised at 0.5amps but when i reconnected the alternator is was still just shoiwng 0.5amps which should take 200 hours to flatten the battery not like 12hrs.

200 hours? your calc is prob down to zero volts not 11or so volts which is prob the lowest it would turn the car over at. you also need to test it with the car locked etc as this is how it 'normally is' & wait a good couple of mins for everything to 'settle' tho as has been pointed out modern cars randomly start things at odd times just cause they can, which makes finding a fault like this a right pain!

[Pork_n_Beem]

Thanks guys got some good ideas to work with. There is no tracker and no traffic master. The car was locked and i waited 10 mins for all to settle down.

As far as i was concerned everything was "off" -

Will look at the climate control thing, any more things to look at gratefully received - cheers

[V8_chitty]

Classic hedgehog symptoms. Had exactly the same probs on my 523 touring. I can recommend a search on all the uk bmw forums, search for hedgehog (honest!). Changing it is a 10min job but it's a sod to reach unless you're mrs incredible. Easy fix though - there is a post with full instructions somewhere

[< FORZA WEST]

Just a note when your checking the drain...Make sure you wait for 16 minutes as the general module is still cative to this point, you can still see 350 -500 ma upto 16 mins.

Heater resistor pack is a common one and also the drivers side window switch pack.

[eliot]

Fox- said:

Had any problems with your climate control lately? This sounds like it might be the final stage resistor which controls the blower etc. It has a mind of its own when it fails and will do things like turn your blower on at 2am and flatten your battery.

+2
Had the same problem - every now and then would try to start car in the morning and it was totally flat - not had this problem since then.

I found the other photos on the net a little small, so I took my own photos of the job which are here:
http://mez.co.uk/forum/viewtopic.php?t=413

[Pork_n_Beem]

thanks very much will serch for my hedgehog...

[Pork_n_Beem]

Update, changed the hedgehog which was absolutely red hot when i removed it after the car was stood for 2 hours.... so i am confident the problem has been fixed.

Many thanks internet, cost £44 ordered online, fitting is easy but did need pliers to get the plug off.

Done in 20mins but would be much quicker 2nd time around.

[noumenon]

[fixedwheelnut]

Don't forget to leave the car for 20 minutes to go in to sleep mode after connecting the ammeter, leave the glove box open and wait for the light to go out is the best way to check it.

Generally the amp reading is approx 0.8 amps for the first few minutes then drops to around 0.15amps / 150ma

Once the car is asleep the amp reading should be no higher than 0.04amps/40ma

Hedgehog is the most popular cause also check the radiator cooling fan.

[Pork_n_Beem]

noumenon said:

LOL -