2004 BMW X5 Voltage problems

GOONER305

MEMBER
2004 BMW X5
V8
2WD
AUTOMATIC
60,000 MILES

Hi. I have a 2004 bmw x5 4.4 L it has an electrical problem. If I leave any door open for one min the battery will drain fast to 10V. I had the battery and alternator checked by advanced auto parts and was told they wore good. If I put a voltmeter across the battery terminals it will read 12V. With the car (ON) it will read 13.5 - 14.1V and then it will read 11V at 2000 rpm. And then back to 13.5 - 14.1 V. And some times the car will be good for a week and back again with the problem.

6 Replies

DOCHAGERTY

MECHANIC
9,601 POSTS

The first thing I see when you speak of the door being open and killing the battery is the battery is old and might require replacement. Is the battery original equipment? If so I recommend replacement irregardless of the opinion of the auto parts guys. ANYTIME the battery voltage goes to 10 volts it means there is a shorted cell and they don't always show up in a test performed by non-qualified personnel. I do not mean to denigrate what the parts people (who work very hard and are good at what they do) but they are not mechanics. I am going to ask that you trust me on this, replace the battery, don't buy the cheapest one out there, lets face it. You bought a BMW, get the premium quality battery.

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Thursday, July 3rd, 2008 AT 7:28 PM

GOONER305

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3 POSTS

Yes the battery was replaced with a interstate battery it's one year old. Not a oem battery. Thats how it came when I bought the car. I guess the first owner changed it.

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Thursday, July 3rd, 2008 AT 8:40 PM

DOCHAGERTY

MECHANIC
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OK, interstate makes a good battery. Now it seems that it may be at fault if the voltage goes to 10 volts, something is not right. A fully charged battery will show at least 12.5v at full charge. If the voltage at the battery goes below 13v with the engine running then there is an issue with the charging system.

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Thursday, July 3rd, 2008 AT 10:27 PM

GOONER305

MEMBER
3 POSTS

First of all I really appreciate you taking the time to help me out. Youre really appreciated. With the engine running Im getting a volt meter reading of 11.1 to 11.0. Instead of the usual 14.0 volts. When I drive the car, I can feel a sudden loss of power as my rpms decline a bit, then The "DSC 4X4 inactive" message shows up as well as the "ABS" light the "Airbag light". And ofcourse the "TRANS FAIL SAFE PROG" message, I turn the car off and then it wont start again, I have to jump the battery to turn the car on, and once again all those messages are gone and the car runs fine. Has done this on several occasions.

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Thursday, July 3rd, 2008 AT 11:00 PM

DOCHAGERTY

MECHANIC
9,601 POSTS

If the voltage is not steady then the charging system is suspect. An intermittently variable issue might require scanning the car for faults with the proprietary software at the dealer and at some independent shops.