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Discussion Starter · #1 ·
I have a 2010 X3 with a charging issue. Before I replaced the old alternator it would put out 12.5 v to 13.2 volts according to multiple battery testers. All the testers stated the battery was ok but needed charging. The battery is a BMW battery 1 ½ years old with 720 CCA.
The battery light never went on nor the head light never went dim. When I used the AC it would drain the battery at a rapid pace. Oher wise the car would run for a few days with the cranking getting slower and slower until it wouldn’t start the car.
With the new alternator (BMW Remanufactured 180 Amp Alternator - Bosch AL0841X) the output is now 13.2 to 13.4 Volt. Not enough to keep the battery charge and after a few days I have the same problem of slow to no cranking.
I am at a lost on what to try next.
Thanks for all help.
 

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In my x3 i have a calcium battery and those require above 14v to charge, can you check your battery type? Other thing try to open the hidden menu using the set key on your dashboard simultaneously with the key fob to get a reading of the volt on your dash in both case engine on and off; you can watch a youtube video on how to get to this menu,,,, if all is good and you're convinced that your battery is good you would have to check if there is an electrical leak draining your battery while the car is off! It could be anything from a small light to an electrical water pump defect. I have had the same issue draining the battery it turned out to be that my water pump had a short and turns by itself from time to time and it draws over ten amps,,, when you take the key off and lock the car voltage remains on several parts of the car!
A good electrician can detect current draw while all is off.
HTH
 

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OP: Read on here about replacing your ground straps, and adding an extra directly to the engine head.
 

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Discussion Starter · #4 ·
In my x3 i have a calcium battery and those require above 14v to charge, can you check your battery type? Other thing try to open the hidden menu using the set key on your dashboard simultaneously with the key fob to get a reading of the volt on your dash in both case engine on and off; you can watch a youtube video on how to get to this menu,,,, if all is good and you're convinced that your battery is good you would have to check if there is an electrical leak draining your battery while the car is off! It could be anything from a small light to an electrical water pump defect. I have had the same issue draining the battery it turned out to be that my water pump had a short and turns by itself from time to time and it draws over ten amps,,, when you take the key off and lock the car voltage remains on several parts of the car!
A good electrician can detect current draw while all is off.
HTH
I have a 2010 X3 with a charging issue. Before I replaced the old alternator it would put out 12.5 v to 13.2 volts according to multiple battery testers. All the testers stated the battery was ok but needed charging. The battery is a BMW battery 1 ½ years old with 720 CCA.
The battery light never went on nor the head light never went dim. When I used the AC it would drain the battery at a rapid pace. Oher wise the car would run for a few days with the cranking getting slower and slower until it wouldn’t start the car.
With the new alternator (BMW Remanufactured 180 Amp Alternator - Bosch AL0841X) the output is now 13.2 to 13.4 Volt. Not enough to keep the battery charge and after a few days I have the same problem of slow to no cranking.
I am at a lost on what to try next.
Thanks for all help.

It is an AGM battery. From what I understand the alternator should be putting 13.5 V to 14 v with 14 v to charge the battery with 14 v being ideal. I do not believe it is an alternator issue at this point as Bosch is an BMW OEM replacement and they are tested at the factory before shipment.
Also I do not know how to use the dash boar but I have tested it with INPA. Bavarian Technic and Toad and all tested out at 13.2 volts
 

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thanks I'll check it out
Imagine electricity is like water; it has to be able to flow. It flows from the battery or alternator, through the various resistors (lights, starter, DME, etc) through the chassis back to the battery. If the return path (ground) is bad, electrons can't flow, and the alternator won't "put out" its proper level; it'll only put out what can flow. Stock ground straps on these are as disposable as kleenex. Heed the above post.

One of my careers is to maintain engines whose single cylinders are the size of a BMW engine. If the alternator output drops below 14v, that engine is taken out of service because there is a problem. Output shouldn't drop below 14v. The output on my E83 has never dropped below 14.3 volts in 183k miles, and is typically 14.5-14.6v all day every day; yes I constantly monitor it using an on board voltage monitor.
 
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