E46 318ci m43 Battery Warning

[jeff87]

Hi all bmw sifus,i need some help from you all.

I just get my first UDM last few days and yesterday i went to change a new battery due to battery weak.So today the battery warning light sudently appear when im cruing on the street and at the same time the aircond compressor is not function also,no more cold wind from the blower.the car idle is normal and no other warning lights appear.But when i pressing the throttle to the deep untill the rpm going 4.5k above then the battery warning lights will disappear.

So is the aircond compressor failure or the alternater failure to cause the battery warning light appear?

 

[jarance]

You can use the special function to check the alternator output voltage.

There is a high possibility that the alternator is the problem.

 

[jeff87]

Thks jarance for the remind,i just check out the voltage when idle is 12.3v~12.5v,i think is the alternator problem.but will it effect the aircond compresor also?and how much is the cost to replace alternator?new or halfcut price?

 

[jarance]

The voltage should be about 13.2 to 14.6VDC in order to charge the battery properly. (about 1.2 to 1.4 times of 12VDC).

When the voltage is low, many things will go crazy and that include the air compressor.

The alternator is serviceable. Usually the problem is to due to worn out carbon brush.

There are some electrical mechanic who are willing to change the carbon brush for you.

Maybe someone can recommend the shop or have done it before.

 

[effierizal]

Hi Jeff87,

You can try to go to this shop in Sunway called T & T (03-56342123). They deal in alternators & a/c compressors repairs.

Did mine 4 years back.

Hope this helps..

 

[tweiboon]

1 Carbon cost u rm15. Normally needs to change both so u need to pay rm30. If you can diy urself then u only need to pay rm30 for changing carbon.
I DIY my alternator and u can see it here https://www.facebook.com/photo.php?fbid=297773753741542&set=pcb.701778546566093&type=1&theater