Battery not charging (but battery light not on)

[mcfee03]

Hi,

I did my first mechanical task of removing my intake, replacing my ccv and disa.

• The car was not started/driven for 3 months.
• negative cable disconnected from the battery (in the boot)
• positive cable disconnected in the engine area.
• When start the car (has to be on jumper leads) volt meter shows it at 12.x.
• I bought a new battery, and it also would not charge (IE not charging?)
• When car starts (with new battery)- voltmeter reads 14.xx, then quickly drops down to 12.xx

In taking off my intake- is there something that could be disconnected to cause this?

Is there a way to test if the alternator is the definite cause? I can remove the alternator easily.

Could it be the alternator regulator or some other part related to the alternator?

[Crowz]

Did you plug the harness back into the alternator fully?

Also check fuse number 5 and fuse number 15 in the glovebox.

[mcfee03]

Originally Posted by Crowz

Did you plug the harness back into the alternator fully?

Also check fuse number 5 and fuse number 15 in the glovebox.

I did connect the electrical harness back fully. Fuses are good.

I forgot to mention- when the car started (with a new battery)- it starts at 14v, then quite quickly drops down to 12.xx and doesn't go any higher.

Does the E53 have an alternator that disengages?

[mcfee03]

I'd be pretty comfortable removing my alternator.

Should my ODB tool be telling me if there's a bad alternator? Would some advice to save me replacing the alternator if it could be caused by something else.

Is it a bad idea to buy a second hand alternator?

BMW X5 ALTERNATOR PETROL, 3.0, M54, E53, 02/01-12/06 01 02 03 04 05 06

[Crowz]

Normally I would just say replace the alternator but if it worked before you did the intake and suddenly doesn't after the intake job I hate saying its "bad". Alternators do have to go bad one day so its possible its bad but that sure seems like a strange way to go out like that.

Its worth a shot swapping it out at least. If it charges after changing it then the alternator was bad

[wpoll]

If the alternator is bad (or at least isn't charging the battery) you should have an orange battery symbol up on the dash when the engine is running. Do you?

[mcfee03]

Originally Posted by Crowz

Its worth a shot swapping it out at least. If it charges after changing it then the alternator was bad

Is this my only option? I don't have a spare alternator around to put it in with!

Originally Posted by wpoll

If the alternator is bad (or at least isn't charging the battery) you should have an orange battery

Nope, I do not see the battery symbol. If this is the case- what could it be?

[Crowz]

Do you have parts stores around you that can test it for you? Autozone for example can test the alternator off the car for free here.

[mcfee03]

Originally Posted by Crowz

Do you have parts stores around you that can test it for you? Autozone for example can test the alternator off the car for free here.

Doesn't seem like it- I had a quick check on google.

Is the problem strange because the battery light _should_ be on if the battery is bad?

[andrewwynn]

If the alternator won't hold 13+ volts it is malfunctioning. It requires some initial voltage to start but then it is self powering. My alternator stopped working properly last winter when it got covered in oil from a bad leak. The bushes were worn and combined with the oil it stopped outputting proper voltage at idle.

Will your alternator output proper voltage at higher rpm? If so it is likely either the brushes or the regulator, either can be replaced. I bought a kit for $20 to replace my brushes and slip rings. My regulator was fine but I found for as little as $40. I had mine tested for free right after replacing the brushes and slip rings and to the shock of the guy at AutoZone it tested fine. The period of non use could have led to some corrosion on the worn slip rings that acted like the oil film in my case. It is simple to take the regulator off not exactly simple to remove the alternator


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