E53 4.4 N62 2004 no electricity
 

I have owned this car now for five years. On every spring and every fall I have had this kind of issue, that suddenly, during normal driving, the car seem to lose voltage in the battery. It starts to turn on ABS lights and all other different lights and warnings until the car just stalls. When trying to restart it, then it behaves like the battery would be dead. Since now, it helped when you jump started the car by using the plus and minus which are located under the hood. Basically just connect the wires, even 5 sec worked and then it starts and works as it should until next time which happens usually after every 6 months. Also when the battery would be dead, then it would not have worked since with only connecting the wires from other car and right away removing them. It is really odd, but it has been like this all the time from the time I have owned the car, around 5 years.
Today morning, I started the car for warming it up due to cold weather, everything was nice, but after 5 minutes it started the circus, until it died completely. But now the jumpstarting does not help anymore as it used to, it seems that it runs only that long, as you charged the battery when jumpstarting the car with one other car.

I checked the connections in the trunk and the battery connections and everything seems ok. Are there somewhere some kind of typical power cable connection points which I could check besides the trunk?

Have you tested the battery? It sounds like it could be an intermittent open-circuit battery.

How to test the battery? When the issue would be the battery, would the car then run when I would disconnect one of the battery terminal for diagnosis?

It's not a good idea to disconnect the battery while the car is running - that can cause electrical problems.

Battery testing is best performed on a fully charged battery using a battery load tester but you can get some idea of the charge state of your battery with a multi-meter - simply measure the no-load voltage (i.e with the negative terminal removed).

https://www.fastfix.com.sg/wp-conten...ce-980x735.jpg

In addition to the battery terminals on the battery, there are at least two other connections that might cause your problem. One is the "Battery Safety Terminal" (BST) on the positive battery lead.

https://lh3.googleusercontent.com/pr...J1EPtdc-EU-sZo

Another possible problem location is at the positive jumper connection under the hood (bonnet) - it can get loose and disconnect the battery.

It's labelled "THRU BULKHEAD UNION SPLICE" in the image below: -

https://xoutpost.com/attachments/x5-...ns-diagram.jpg

(NOTE: The image shows the B+ terminal as a separate line but in many E53 X5s, it is at the union splice location)

Hope that helps... :thumbup:

How to access the THRU BULKHEAD UNION SPLICE?
Under the car or is it accessable under the hood?

The splice is at the B+ jump terminal - remove the windscreen scuttle to access the joint behind the bulkhead...

Starting & charging systems testing techniques
Here are a few quick tests to determine a battery issue, a charging system issue, or a primary wiring issue.

Skill Level: 2 + (read and follow instructions)
Tools required: Digital Volt Meter (DVM), battery terminal cleaning tool, and 8mm, 10 mm sockets and ratchet with extensions.

You need to read battery voltage before starting any test on an electrical system as it will influence the results of Starting, Charging, and electrical tests of any kind. (Note: battery must be fully charged, see chart below).

Step One: Get out a digital volt meter, Read battery voltage (Key off). Read voltage (Key on) at the following points Battery, under hood jump point, and at the alternator. You only need to determine if you have 12 volts at the alternator with the key on (BIG FAT WIRE). A simple handheld digital wave form tester will get you in the ball park when it comes to batteries. (Further discussion on these testers is for another engineering forum).

Step Two: You need to read the voltage at the BATTERY at idle, 1500, and 2500 RPM to determine voltage regulator function. Better still would be a Volt Amp tester (VAT-40 Image below) to induce a correct AMP load to read actual AMP/Volt output from the alternator and battery, as that is the only true testing method. Having a DVM that has min/max capability will make your testing easy.

Step Three: Remove and clean each and every ground in the trunk, jump point, and at the frame rail for the block (bad grounds = lots of electrical issues). Clean the starter/alternator cable connection under the car, just under the dead pedal. (E39)

Step Four: Failure to get correct output on running test means DEAD alternator (volt regulator, brushes, windings, etc.) Remove and bench test the unit or drag it to your local auto parts store for a second opinion (which will be worth exactly what you pay for it....)

Base line numbers
Battery Voltage should be 12.6+V (Key off) See chart below.
Battery voltage should be 13.5v - 14.5v on running tests (note large fluctuations at running RPMs is a SURE sign that the Volt Regulator is not doing its job. Smack with rubber hammer and retest. Rebuilt units have large variance of quality control from good 85% of the time to approx 50/50%.

NOTE: The exact charging voltage will vary according to the battery's state of charge, the load on the vehicle's electrical system, and temperature. The lower the temperature the higher the charging voltage, and the higher the temperature the lower the charging voltage. The "normal" charging voltage on a typical application might be 13.8 to 14.3 volts at 77 degrees F. But at 20 degrees F. below zero, the charging voltage might be 14.9 to 15.3 volts. On a hot engine on a hot day, the normal charging voltage might drop to 13.5 to 14.3 volts.

Note 2: TIS specifies alternator voltage as 14.3 +/-0.1 V. But that is measured at the alternator output post. The values seen using the cluster will be 0.5 V or more below the alternator voltage output.

Batteries surface charge.

What the heck is a surface charge?
When testing wet cell auto batteries, some will show a 12.xx Volt result, but as soon as a 100-150 amp load is applied, they drop straight down to 9.8V or lower. Classic example of a collapsed cell wall (internal short). This is why too many DIY and techs get stumped when they pull out a meter and say "It shows 12.xxV so it must be good”. NOPE, batteries are tested for voltage holds and AMP draw capacity as well as the ability to recover and recharge over and over again. Batteries are nothing more than an energy storage device. Their usage back in the 1920's allowed for a "self-starter" option, now days we take it for granted. In the future we will use the engine ignition system to fire off a cyl while disabling all other cyls (opening the exhaust valves) allowing for a start that requires no electrical/mechanical starter. A topic for a SAE publication but an interesting future none the less. The challenge is for the average DIY to approx. the load test with KEY OFF.

Solution: Set a volt meter to DC volts 0-25 scale or auto ranging if so equipped. Read and record voltage
Turn on everything in the car for 15 seconds:
Headlamps to high beam
Heater blower motor to high w/ A/C on
Seat Heaters
Rear Defroster (and rear seat blower if so equipped)
Interior lights
Radio
Fog lamps
Cigar lighter
etc, etc, etc

Read voltage after testing. You should see a drop off of .5-1.5Volts during the test and a slow rise back to 12.5V+ on a completely healthy and fully charged battery in 30sec to 1 min.
A battery that is DEAD, will show 9.8V or less and never recover until charged.
Battery Registration: There is NO battery registration required for proper operations in a E39 or E53 application.

Alternator testing tips
To quote another poster...

How to load the alternator at engine idle for alternator output tests:

Note: Alternator output should be tested with the engine idling under the following four loads after at least 15 seconds of idling (for the alternator to ramp up):
Turn the high beams on
And, turn the rear defroster on
And, turn the fan on (full force, I guess)
And, turn the wipers on (to the regular setting, I guess)

These loads should be left on while the alternator output tests are being performed.

Once access to the alternator is gained (access for the I6 is vastly easier than the V8):

• Check the voltage from the alternator #30 post and ground
o It should be the same as the battery voltage
• Now disconnect the harness connector to the alternator:
• Check voltage from terminal 15 and ground (field voltage)
o It should be the same as the battery voltage

More info: Another way to check alternator output is with an oscilloscope. Observing the "ripple voltage" pattern will tell you at a glance whether or not all the alternator windings are functioning. A "good" pattern should look like the top of a picket fence. If any of the humps are missing, it means one or more of the windings is grounded or open, or there's a bad diode. Most battery/charging system testers also have a test function that can detect bad diodes.
Ripple testing with a DVM:

ANOTHER QUICK CHECK FOR BOSCH ALTERNATORS

One way to check the integrity of the alternator and diodes on Bosch alternators is to check the voltage readings at the D+ (blue wire) terminal and B+ terminal. The voltage reading should be the same at both terminals. A difference of more than one volt would indicate faulty diodes and the need to replace the alternator.
Tips link: https://www.diyauto.com/manufacturer...ion-by-bluebee

Volt Drop Testing (Image below) will show you issues with grounds and wiring problems. Read the text and test a few spots to determine if your car has clean connections.
https://www.engine-light-help.com/voltage-drop.html

Are you having other electrical issues? Alternative issues: Ignition Key switch failure, wiring junction box rusted (see water leaks under passenger seat (E39), Water standing in trunk under the battery (E53) and the normal wiring broken connectors, grounds), etc....

Tip Sites for more info:
https://www.aa1car.com/library/2002/cm10220.htm
https://www.bimmerfest.com/forums/sh...d.php?t=510579 (Everything you wanted to know about BMW starting and charging systems for DIY)
Need a Video? https://video.search.yahoo.com/searc...d&action=click

Helpful?
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