BMW X5 and X6 Forum 2014-Current
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Post Reply
 
Thread Tools Search this Thread
      07-13-2015, 11:17 AM   #1
ajob
First Lieutenant
Monaco
174
Rep
328
Posts

Drives: X5 M
Join Date: Jun 2015
Location: Monaco

iTrader: (0)

Why two batteries?

The new X5 M (F85) has two separate car batteries.

Does anybody have a clue why -- and which battery does what?

What happens if the left or the right one, or both, fail?

Do all F15 have two batteries, or only the F85 ?
Attached Images
 
Appreciate 0
      07-13-2015, 12:12 PM   #2
JNoSol
Brigadier General
JNoSol's Avatar
United_States
1231
Rep
3,822
Posts

Drives: 750 MSPORT
Join Date: Feb 2012
Location: Kansas City

iTrader: (0)

X5m has 2 batteries, 90mah + 50mah. X50i has a single 90mah while X35i has a single 105mah (which is strange, but I bet the X50i has lithium vs standard - the maintenance scheduled of the X50i is less frequent on the battery compared to X35i). X35d has 2 batteries as well.

I'm very confident that it has to do with e-CAT (electronically heated catylic converters). During cold start, the first battery is used to power the starter (smaller 50mah battery) while the larger battery heats up the e-CAT and all else electronics. This reduced the car's stress from heating up the e-CAT after the voltage is drained from the single battery design, which requires the car to run at the higher RPM to re-charge the battery from a cold start.

The F80 doesn't have an e-CAT. During cold start-up, the turbo wastegates are wide open and the engine RPM goes up + rich fuel to heat up the CATs. So the emission is worst on the F80 during a cold startup compared to an F85. This is also why the F85 sounds so much better at cold starts compared to my last F80.

I wouldn't imagine that if one fails, the other will need to be replaced as well. They're independent batteries tied to the charging grid.
__________________
Daily: G12 750 MSPORT Weekend Car: 981 GT4

Last edited by JNoSol; 07-13-2015 at 12:20 PM..
Appreciate 1
Logical100.00

      07-13-2015, 03:35 PM   #3
ajob
First Lieutenant
Monaco
174
Rep
328
Posts

Drives: X5 M
Join Date: Jun 2015
Location: Monaco

iTrader: (0)

Thank you, JNoSol, for the really solid info!

On the X5 M (same as for the former X5 50i) on a cold start the engine revs higher, about 1100 rpm for some 20 seconds as long as you do not start rolling. I always wondered why, maybe it is just to reduce the heating e-CAT battery drain as you mention above -- if so, it may pay to wait for the higher rev routine to finish, to conserve battery charge.
Appreciate 0
      07-13-2015, 10:21 PM   #4
DaveChapin
Enlisted Member
United_States
18
Rep
36
Posts

Drives: 2016 X5M; 2014 911 TTS
Join Date: May 2015
Location: PNW

iTrader: (0)

I think it also has something to do with having enough juice to safely run cooling fans for up to several minutes after the car has stopped. There are threads around here that this was important for this generation of high output turbocharged engines bmw has been using recently.
Appreciate 0
      07-13-2015, 10:29 PM   #5
JNoSol
Brigadier General
JNoSol's Avatar
United_States
1231
Rep
3,822
Posts

Drives: 750 MSPORT
Join Date: Feb 2012
Location: Kansas City

iTrader: (0)

Quote:
Originally Posted by DaveChapin View Post
I think it also has something to do with having enough juice to safely run cooling fans for up to several minutes after the car has stopped. There are threads around here that this was important for this generation of high output turbocharged engines bmw has been using recently.
There might be some truth to that. Fans don't draw as much power as heating coils inside the CAT though. The X50i fan would run just as long I imagine, but it only has 1 battery. I'm waiting for iND to confirm if our cars have e-CAT as expected or not.

Coming from an F80 M3, I'm shocked how long the F85 fan runs after I parked. The M3's fan didn't run much, if it does at all after it parks.
__________________
Daily: G12 750 MSPORT Weekend Car: 981 GT4
Appreciate 0
      07-13-2015, 11:40 PM   #6
gan23
Second Lieutenant
Canada
45
Rep
226
Posts

Drives: X5M '13 '18
Join Date: Jul 2013
Location: Montreal

iTrader: (0)

The complete electrical shutdown on MY2013 is clocked at exactly 30 min from my experience
Probably the same for F85
Appreciate 0
      07-15-2015, 02:08 AM   #7
SCA
Brigadier General
SCA's Avatar
United_States
429
Rep
3,726
Posts

Drives: Multiple BMWs
Join Date: Apr 2005
Location: 🇺🇸

iTrader: (0)

From what I recall from the automotive press packet, the F85/F86 has 10 cooling fans.
Appreciate 0
      07-15-2015, 09:54 AM   #8
JNoSol
Brigadier General
JNoSol's Avatar
United_States
1231
Rep
3,822
Posts

Drives: 750 MSPORT
Join Date: Feb 2012
Location: Kansas City

iTrader: (0)

Quote:
Originally Posted by SCA View Post
From what I recall from the automotive press packet, the F85/F86 has 10 cooling fans.
I believe it meant 10 heat exchangers? (oil coolers, radiators, trans cooler, intercoolers, etc.)

BMW usually have a single large fan behind the radiator.

The X35i and X50i guys are claiming the fan runs long after stops as well. So the 2 batteries theories for the fans might not apply as they have a single battery.
__________________
Daily: G12 750 MSPORT Weekend Car: 981 GT4
Appreciate 0
      07-15-2015, 01:07 PM   #9
DaveChapin
Enlisted Member
United_States
18
Rep
36
Posts

Drives: 2016 X5M; 2014 911 TTS
Join Date: May 2015
Location: PNW

iTrader: (0)

Quote:
Originally Posted by JNoSol View Post
I believe it meant 10 heat exchangers? (oil coolers, radiators, trans cooler, intercoolers, etc.)

BMW usually have a single large fan behind the radiator.

The X35i and X50i guys are claiming the fan runs long after stops as well. So the 2 batteries theories for the fans might not apply as they have a single battery.
Check out this thread: "Here is the battery replacement SIB for ALL F15 X5"
http://f15.bimmerpost.com/forums/sho....php?t=1126569

This is why I think the bigger battery is about the energy draw from the routine need to drive cooling fas after engine shut off.
Appreciate 0
      07-25-2015, 01:32 AM   #10
dr.waxman
Private First Class
14
Rep
142
Posts

Drives: X5M
Join Date: May 2015
Location: Auckland NZ

iTrader: (0)

Quote:
Originally Posted by DaveChapin View Post
Check out this thread: "Here is the battery replacement SIB for ALL F15 X5"
http://f15.bimmerpost.com/forums/sho....php?t=1126569

This is why I think the bigger battery is about the energy draw from the routine need to drive cooling fas after engine shut off.
That is what I believe too.
It's all about the cooling fans
Appreciate 0
      08-24-2015, 10:00 PM   #11
onfireX5
Brigadier General
2565
Rep
3,604
Posts

Drives: F90M5,F85X5M
Join Date: Jul 2015
Location: Va

iTrader: (0)

FWIW my X5 35i has two batteries like the above pic.
Appreciate 0
      08-25-2015, 12:37 PM   #12
JNoSol
Brigadier General
JNoSol's Avatar
United_States
1231
Rep
3,822
Posts

Drives: 750 MSPORT
Join Date: Feb 2012
Location: Kansas City

iTrader: (0)

Quote:
Originally Posted by onfireX5 View Post
FWIW my X5 35i has two batteries like the above pic.
Yep. X5 35i / 35d / M all have 2 batteries. Oddly enough, the X5 50i doesn't have 2 batteries but just one large battery instead.

After observing the X5M DPs, it's not an eCAT which requires the battery to heat it up during cold start. It's due to the fan running 10-15min after shut down. The primary battery is not used for the fan cool down so there's enough amp to start the car.
__________________
Daily: G12 750 MSPORT Weekend Car: 981 GT4
Appreciate 0
      08-25-2015, 04:03 PM   #13
wdimagineer
Major
wdimagineer's Avatar
United_States
322
Rep
1,377
Posts

Drives: 2015 X5 M
Join Date: Nov 2011
Location: San Francisco, CA

iTrader: (0)

Quote:
Originally Posted by JNoSol View Post
Yep. X5 35i / 35d / M all have 2 batteries. Oddly enough, the X5 50i doesn't have 2 batteries but just one large battery instead.

After observing the X5M DPs, it's not an eCAT which requires the battery to heat it up during cold start. It's due to the fan running 10-15min after shut down. The primary battery is not used for the fan cool down so there's enough amp to start the car.
My 50i had two...
__________________
Current: 2015 X5 M - Donington Grey/Mugello Red - DINANTRONICS Stage 2 + Free Flow Exhaust - Bimmerpost Featured!
Past: Bimmerpost Featured 2014 X5 xDrive50i 2014 Jeep SRT 2013 Tesla Model S P85+ Bimmerpost Featured 2013 F10 M5 2012 550 xDrive 2011 M3 ZCP
Appreciate 1
      08-25-2015, 06:28 PM   #14
JNoSol
Brigadier General
JNoSol's Avatar
United_States
1231
Rep
3,822
Posts

Drives: 750 MSPORT
Join Date: Feb 2012
Location: Kansas City

iTrader: (0)

Quote:
Originally Posted by wdimagineer
Quote:
Originally Posted by JNoSol View Post
Yep. X5 35i / 35d / M all have 2 batteries. Oddly enough, the X5 50i doesn't have 2 batteries but just one large battery instead.

After observing the X5M DPs, it's not an eCAT which requires the battery to heat it up during cold start. It's due to the fan running 10-15min after shut down. The primary battery is not used for the fan cool down so there's enough amp to start the car.
My 50i had two...
Well damn. The specs online lied.
__________________
Daily: G12 750 MSPORT Weekend Car: 981 GT4
Appreciate 0
      10-28-2019, 11:37 PM   #15
~ViO~
Enlisted Member
~ViO~'s Avatar
11
Rep
40
Posts

Drives: 2013 X6M, 2015 X6 50i
Join Date: Oct 2019
Location: Boston, MA

iTrader: (0)

Quote:
Originally Posted by wdimagineer View Post
My 50i had two...
Yes, same here... My 50i has two batteries as well... Perhaps this link will explain why two batteries... I think you need to have a combination of the following options?

https://www.realoem.com/bmw/enUS/sho...diagId=61_5900

Last edited by ~ViO~; 10-30-2019 at 05:32 PM..
Appreciate 0
      10-30-2019, 04:15 PM   #16
menelaos
Lieutenant Colonel
912
Rep
1,638
Posts

Drives: 2015 BMW X5 F15
Join Date: Nov 2017
Location: Cheboygan, MI

iTrader: (0)

Two batteries are there if you have add'l 12V sockets!

https://f10.5post.com/forums/showthread.php?t=1575215

Last edited by menelaos; 10-30-2019 at 04:29 PM..
Appreciate 0
      10-30-2019, 05:33 PM   #17
~ViO~
Enlisted Member
~ViO~'s Avatar
11
Rep
40
Posts

Drives: 2013 X6M, 2015 X6 50i
Join Date: Oct 2019
Location: Boston, MA

iTrader: (0)

Quote:
Originally Posted by menelaos View Post
Two batteries are there if you have add'l 12V sockets!

https://f10.5post.com/forums/showthread.php?t=1575215
I have that option as well... Thank you! 😀
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off



All times are GMT -5. The time now is 04:40 AM.




xbimmers
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST