Battery Drain issue

[AW8]

Glad info helpful.

Powered down, the fuse test should only take about 10 mins. The Draper tester can be sourced & delivered for under £4, (if tester not owned).

As for the emergency release, there's one in the rear o/s storage for releasing the fuel flap too.......(both covered in the owners manual).

Good Luck.......whichever route you take.

[jason@bwchiptune]

These cars can have problems with the moduals or ecu's having a high resistance or short in them causing power drain some times,the problem is having them on fault for long enough before the battery go flat to find the problem as after a flat battery the fault will go away till the next time

[Mikee]

[quote=""jason@bwchiptune""]These cars can have problems with the moduals or ecu's having a high resistance or short in them causing power drain some times,the problem is having them on fault for long enough before the battery go flat to find the problem as after a flat battery the fault will go away till the next time[/quote]


Thats interesting. Had the car at a specialist again yesterday and they mentioned they now think it may be the multi function control unit behind the fuse panel in the glove box. They reckon it now needs to go to BMW as they are the only ones who can sort it. Is that true? IF it is a short in the circuit board can this just be fixed or replaced and is it expensive. Really don't wanna go back to the stealers unless it's the only way to sort the car...

[X5Sport]

A couple of other things to think about.

How old is your vehicle battery? If it's the original one it may actually have an ibtermittent fault.

When you say your battery is fine, how was it tested? BMW's own tester can report a bad battery as being good.

Do you have by mens of checking the actual battery voltage? A good battery should be at least 12.2-12.6V at the battery terminals off-load (disconnected). Do not measure the voltage within 4 hours of running the car due to residual charge being left on the plates - it could give you the wrong impression about the battery.

If you have a built in car phone (I have the Siemens one) then the advice about making sure it powers down is very good. Mine stayed up sometimes for a couple of hours. Not enough to kill a battery overnight though.

If your battery volts are good yet you still have difficulty starting the car then start to suspect the starter motor too. Mine went faulty and on start was drawing more current than the battery could deliver which causes a voltage drop. This then affects the electronics and the car won't start. It gives every indication of being a dead battery when it's actually too much demand from the starter. I think the normal starting current is somewhere around 700Amps, the battery is rated to around 800A. Mine was drawing in excess of 950A and the battery simply could not cope, nor could the alternator put enough back in on the 20 mile journeys I was doing.

It took BMW a while to identify it as the GT1 test systems showed no fault. One of their older Tech's went back to first principles and checked the current draw. Bingo! One new starter under warranty and problem solved. The Battery survived another two years before being replaced, but it was getting very bad at the end and not really holding a full charge anymore. It might not be your issue, and it needs special test equipment to measure that high a current, but it is a known fault and I thought I'd add it to your checklist just in case. You need a device called a DC Current Clamp, rated to 1,000Amps. It must be a DC version, an AC current clamp will give the wrong results.

[Mikee]

Thanks mate

Battery is new. About 6 months old, and had starter motor replaced at the end of last year. The specialists tested the charge on the battery and the alternator and everything was working ok. They did record an intermittent drain over a 24hr period but it never lasts long enough to find where it comes from.

[X5Sport]

At least those can be eliminated. In answer to your query about the multi-function unit, it may require programming by BMW and possibly may be a part that has to be linked in properly and coded with VIN data etc so that it works in your car.

Did they tell you what this unit does? See if it's listed on Realoem. That might give you a $ price at least.

[AW8]

Mikee,

Sorry to hear you haven't sorted this yet.....

1. Did you proceed to check a-e as my prior post ?

2. Is the specialist you refer to a BMW indy expert using GT1 ?

I know my advice is basic but if your diagnostic skill not much better than mine I would try to eliminate basics & then take it to a good indy as I know my limitations.

In total fairness to Jason you cant expect him to give a definitive answer if he hasn't seen the car.

Dealers have back up of BMW but indy's often have same kit, significant experience &/or own back up networks.

[Mikee]

Hi AW8

I've checked everything I can, and disconnected TM, don't have a Phone hooked up or any DVD screens etc. It is almost impossible to perform a check though as like I said the battery is drained at completely different intervals. Sometimes the car behaves normally and to check it you would think I was talkin' crazy. You can only find the drain when its happening if that makes sense...

[AW8]

Mikee,

I can tell you are getting fed up with this.......I would be too

You say you have done everything you can do & it's good that you have ruled out DVD/TM/Phone issues.

Please let me try to help you by answering the following questions specifically..........

1. Did you perform a post shut down fuse test as per my earlier advice ?

2. Did you check for effective engine run operation of the aux/push fan ?

3. Is the specialist you used a BMW expert using GT1 ? (I say as this as you prior sought opinion as to the integrity of advice given to take car to a dealer. Sought opinion on that advice may depend on the credentials of the "specialist" &/or what equipment they have used).

I have current drain & after research I checked & found my aux/push fan to be defective. This now confirmed by trusted indy who also checked car with GT1. Indy adamant my defective aux/push fan causing current drain & battery issues. I have had flat battery when my car not used much other times in similar circ's it seems fine. I know battery & FSR are serviceable & correct.....Ctek charger has been earning it's keep, (safe way to charge without causing battery damage). Aux fan on list of things to do but I have had insurance, tax & radio module for X5 in last week as well as having to sort issues on Z3. (Just as you also have to keep the M3 happy I too have 2 maturing BMW's to attend to)

Speak soon

[Mikee]

AW8,

1. No. Not personally, but the auto electrician has. I have stayed in the car after shut down to see if any obvious gremlins are at work. ie Monitor coming on, lights not extinguishing etc. But the drain is not permanent and doesn't automatically occur on shutdown of the car. Thechances of catching the drain in action seem quite slim. The car has been at the auto electrician (not BMW specialist) a couple of times and they have had the car hooked up to catch drain for 24 hours at a time but not been able to find it. I've also left the car for 48 hours without touching it and its been fine. I can't obviously be certain but I'm sure if I did the test the car would SEEM to be fine.

2. The push fan seems to work ok, but could it still drain the battery even if it apparently was workin ok?

3. Auto electrician was not a BMW specialist. Has done quite a bit of work for me and my Dad on cars over the last few years, so when I had an electrical issue I immediately thought he would be the man for the job.TBH I think even he's a bit embarrassed about not being able to sort it out as he didn't even charge me the last time the X was in for a couple of days.

Next Port of call will be specialist BMW tech to try and sort this out.


Thanks again AW8

[StewieG]

I'm doing the fuse check now. Should I allow for the fact the glove box light is on so not count the power to the fuse?

[StewieG]

Help

I powered down X5. Checked fuses and there were loads still with power...
I noted fuses for alarms and expected those but out of 60 fuses 28 were powered while car was in sleep mode.