Alternator voltage really high - Bimmerfest - BMW Forums



Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series & 8 Series > 7 Series - F01 / F02 (2009 - 2015)

7 Series - F01 / F02 (2009 - 2015)
The 5th generation F01/F02 BMW 7 Series flagship forum. The redesigned 7 series leads off the BMW Fxx chassis code, offering an 8 speed automatic transmission and all turbocharged engine options.

Reply
 
Thread Tools Display Modes
  #1  
Old 10-20-2019, 09:04 PM
Johnyboy30327 Johnyboy30327 is offline
Registered User
 
Join Date: Sep 2019
Posts: 8
Mein Auto:
Alternator voltage really high

Hello everyone. I have a 2011 750li xdrive and lately I have received a Ton of electrical messages. The biggest being my turbine speed sensor signal low and the transmission malfunction going into limp mode.

I think the cause may be my alternator. The voltage is really high. I have. Attached an image. It seems to be pushing out 15V to 15.5V and my battery is jumping up to 15V. Iím guessing this is not normal.

Can someone please help. Iím getting errors in modules from the all around camera system, pdc, transmission, instrument cluster, etc. Very vast selections of systems. Iíve been monitoring the voltages through my BimmerLink dashboard. Click image for larger version

Name:	IMG_3431.jpg
Views:	44
Size:	54.3 KB
ID:	868911

Thanks
Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old 10-20-2019, 09:59 PM
Markst Markst is offline
Officially Welcomed to the 'Fest
Location: Marg
 
Join Date: Apr 2018
Posts: 256
Mein Auto: BMW 5
15v is fine if you don't have an AGM battery. Generator setpoint voltage is the voltage the ECU is asking from the alternator.
Measure with an actual multimeter on the battery terminals and on the alternator.
Reply With Quote
  #3  
Old 10-21-2019, 08:32 AM
Johnyboy30327 Johnyboy30327 is offline
Registered User
 
Join Date: Sep 2019
Posts: 8
Mein Auto:
Alternator voltage really high

Quote:
Originally Posted by Markst View Post
15v is fine if you don't have an AGM battery. Generator setpoint voltage is the voltage the ECU is asking from the alternator.
Measure with an actual multimeter on the battery terminals and on the alternator.


Ok, Iíll do that today after work and report my findings. Thank you for the clarity in the values.

Also, is the ďgenerator voltageĒ the actual alternator voltage it is delivering?


Johnathan
2011 F02 750li XDrive

Last edited by Johnyboy30327; 10-21-2019 at 08:35 AM.
Reply With Quote
Sponsored Links
Advertisement
 
  #4  
Old 10-21-2019, 10:00 AM
Markst Markst is offline
Officially Welcomed to the 'Fest
Location: Marg
 
Join Date: Apr 2018
Posts: 256
Mein Auto: BMW 5
Quote:
Originally Posted by Johnyboy30327 View Post
Also, is the ďgenerator voltageĒ the actual alternator voltage it is delivering?
It should be, but I don't know how reliable bimmerlink is.
Reply With Quote
  #5  
Old 10-21-2019, 06:42 PM
Johnyboy30327 Johnyboy30327 is offline
Registered User
 
Join Date: Sep 2019
Posts: 8
Mein Auto:
Alternator voltage really high

Quote:
Originally Posted by Markst View Post
It should be, but I don't know how reliable bimmerlink is.


So the battery at every positive point is at 15.08v with the car running and 12V with the engine offClick image for larger version

Name:	IMG_3437.jpg
Views:	24
Size:	69.9 KB
ID:	869027. Iím pretty sure thatís too high as in the past it was never above 14.2v

Bimmer link seemed to be pretty close.


Johnathan
2011 F02 750li XDrive

Last edited by Johnyboy30327; 10-21-2019 at 09:49 PM.
Reply With Quote
  #6  
Old 10-21-2019, 08:23 PM
wjhughes420384's Avatar
wjhughes420384 wjhughes420384 is offline
whughes
Location: Jarrettsville md
 
Join Date: Mar 2007
Posts: 1,992
Mein Auto: 2009 750li, 2018 X5
cHANGE THE BATTERY!!!!,, all kinds of goofy stuff goes on when the battery needs replacing
__________________

2009 750Li - Space Grau Metallic, Camera pkg, Conv pkg, Driver Asst pkg, Lux Seat pkg, Lux rear seat pkg, Prem sound pkg, Sport pkg, HUD, Massaging rear seats, Smartphone integration, Sat radio, MTEC H8 4750K Halo lights,
Dinan Stage 1 SW, Air intake, Free Flow Exhaust, Camber Arm
Reply With Quote
  #7  
Old 10-22-2019, 04:43 AM
Markst Markst is offline
Officially Welcomed to the 'Fest
Location: Marg
 
Join Date: Apr 2018
Posts: 256
Mein Auto: BMW 5
12v with the engine off means the battery is almost dead. The high alternator voltage is the car trying to charge it. How old is your battery?
Can you see more info like battery type/ah/soc on bimmerlink?

Last edited by Markst; 10-22-2019 at 04:46 AM.
Reply With Quote
  #8  
Old 10-22-2019, 03:12 PM
Johnyboy30327 Johnyboy30327 is offline
Registered User
 
Join Date: Sep 2019
Posts: 8
Mein Auto:
Quote:
Originally Posted by Markst View Post
12v with the engine off means the battery is almost dead. The high alternator voltage is the car trying to charge it. How old is your battery?
Can you see more info like battery type/ah/soc on bimmerlink?


Itís a 12v battery from advance auto parts. It has been in the car since I owned it. The local Indy shop said to replace the alternator because the battery at rest isnít dropping below 12V but when the car is on it is jumping up to 15V because the alternator is pushing out 15.2V to 15.5V while operating.


Johnathan
2011 F02 750li XDrive
Reply With Quote
  #9  
Old 10-22-2019, 05:19 PM
Markst Markst is offline
Officially Welcomed to the 'Fest
Location: Marg
 
Join Date: Apr 2018
Posts: 256
Mein Auto: BMW 5
As you can see from your own screenshot the alternator is supplying the voltage the car is asking for, there is a good chance it doesn't need to be replaced. If it isn't working as intended, you can probably fix it just by replacing the voltage regulator on the back.
If you disconnect the battery completely and still measure 12v or less at the terminals, it need to be replaced, it should never get that low.
Reply With Quote
  #10  
Old 10-22-2019, 06:00 PM
HerbP HerbP is offline
Super Moderator
Location: Georgia
 
Join Date: Jul 2009
Posts: 6,952
Mein Auto: 05 645Ci, 14 750 M-Sport
You most likely have a bad voltage regulator, which is a part attached to the alternator. The VR is around a 50 to 70.00 part. The alternator will need to be pulled to replace the VR, then is is a 5 minute job the insert it into the alternator. Usually with a bad VR, you will see warning s from the Dynamic Drive on the IDrive screen.
Reply With Quote
  #11  
Old 10-22-2019, 06:29 PM
Johnyboy30327 Johnyboy30327 is offline
Registered User
 
Join Date: Sep 2019
Posts: 8
Mein Auto:
Quote:
Originally Posted by HerbP View Post
You most likely have a bad voltage regulator, which is a part attached to the alternator. The VR is around a 50 to 70.00 part. The alternator will need to be pulled to replace the VR, then is is a 5 minute job the insert it into the alternator. Usually with a bad VR, you will see warning s from the Dynamic Drive on the IDrive screen.


Yes, I received the dynamic drive warning and the battery tested good 15 minutes ago. I was thinking to replace the entire alternator just because I donít know how old it is and donít want to pull it more than once. But I could try the VR. Where can I buy one I saw some on eBay for $115? I have a 2011 750li Xdrive man. Date 5/2010.


Johnathan
2011 F02 750li XDrive
Reply With Quote
  #12  
Old 10-22-2019, 07:04 PM
Johnyboy30327 Johnyboy30327 is offline
Registered User
 
Join Date: Sep 2019
Posts: 8
Mein Auto:
Quote:
Originally Posted by HerbP View Post
You most likely have a bad voltage regulator, which is a part attached to the alternator. The VR is around a 50 to 70.00 part. The alternator will need to be pulled to replace the VR, then is is a 5 minute job the insert it into the alternator. Usually with a bad VR, you will see warning s from the Dynamic Drive on the IDrive screen.


So...I re-registered my battery using BimmerLink wondering if that could help. Instant change. I will see if this sticks. Click image for larger version

Name:	IMG_3441.jpg
Views:	12
Size:	53.4 KB
ID:	869213


Johnathan
2011 F02 750li XDrive
Reply With Quote
Reply

See More Related BMW Stories


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series & 8 Series > 7 Series - F01 / F02 (2009 - 2015)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



Forum Jump


All times are GMT -7. The time now is 12:50 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
© 2001- VerticalScope Inc. All rights reserved.