Z3MCoupe.com Forums

Go Back   Z3MCoupe.com Forums > M Coupé Technical > Technical Discussion
HOME Gallery Register Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #11  
Old 25-11-2010, 02:03 PM
c_w's Avatar
c_w c_w is offline
Moderator
 
Join Date: Aug 2005
Location: North West
Posts: 8,434
Default

It might be from the risk of damaging the ECU if the terminals are put the wrong way around and shorted, on old cars this probably wouldn't do anything but on "modern" cars could fry something sensitive?
Reply With Quote
  #12  
Old 25-11-2010, 03:31 PM
exdos's Avatar
exdos exdos is offline
Senior Member
 
Join Date: Aug 2003
Posts: 4,819
Default

Quote:
Originally Posted by c_w View Post
It might be from the risk of damaging the ECU if the terminals are put the wrong way around and shorted, on old cars this probably wouldn't do anything but on "modern" cars could fry something sensitive?
You read similar horror stories about people using welders on cars. The scare used to be that the alternator would get damaged and now this also includes the ECU. From what I've read on the subject, it seems that you need to ensure that your connections on the car are clean when attaching the leads and that you don't create sparks and short circuits when making the connections.
__________________
/// Exdos ///
"Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart
Reply With Quote
  #13  
Old 25-11-2010, 03:45 PM
Dave P's Avatar
Dave P Dave P is offline
Administrator
 
Join Date: Dec 2008
Location: Cheshire
Posts: 22,576
Default

here's a article from the BMW car club magazine which makes interesting reading,

__________________
Reply With Quote
  #14  
Old 25-11-2010, 04:01 PM
c_w's Avatar
c_w c_w is offline
Moderator
 
Join Date: Aug 2005
Location: North West
Posts: 8,434
Default

You can do a simple battery change without getting into any of those problems!! Maybe it's a US thing!?


Quote:
Originally Posted by exdos View Post
You read similar horror stories about people using welders on cars. The scare used to be that the alternator would get damaged and now this also includes the ECU. From what I've read on the subject, it seems that you need to ensure that your connections on the car are clean when attaching the leads and that you don't create sparks and short circuits when making the connections.
Yea I think with welding it's highly recommend to disconnect the battery as you're sending high current through the body which "may" affect stuff like ECUs.
Reply With Quote
  #15  
Old 25-11-2010, 04:31 PM
maph maph is offline
Senior Member
 
Join Date: Feb 2009
Posts: 252
Default

My sister has a 09 plate X5 and she has had lots of problems due to flat batteries/ the battery being disconnected.

She returned from holiday and had a flat battery (left an interior light on). BMW road assist sent out a 'technician' who did not even know where the battery was.....after a lot of phone calls he found the battery (although i presume he could have used the under bonnet terminals) and tried jump starting it...... roll on lots of sparks, scared kids etc.

Ended up started buy with numerous problems, loss of sat nav, radio, windows going up and down by themselves etc...... took it into dealer who tried charging her for sorting it out as it was caused by owner error (flat battery).

More recently the battery was disconnected again in a body shop, when reconnected had lots of gremlins.

I am sure the MC is not very sensitive to disconnecting the battery but these new models have issues with it for sure.
__________________
S50 Black, H&R Arbs/ Springs, B8s, Larini Exhaust
Reply With Quote
Old 25-11-2010, 05:54 PM
Neil M
This message has been deleted by Neil M.
  #16  
Old 25-11-2010, 09:05 PM
issproking issproking is offline
Senior Member
 
Join Date: Dec 2008
Posts: 340
Default

Just looked ay the manual myself

It does seem there is certainly a specific procedure for jump-starting, the first one that sticks out is the fact you are not even supposed to touch the flat battery.

As previous poster said the positive needs to be connected to the point in the engine bay and the negative to a special bolt on the strut housing.

Once started it also says to run lights and turn up blower etc for a certain amount of time before disconnecting.
Reply With Quote
  #17  
Old 26-11-2010, 10:24 AM
Dave P's Avatar
Dave P Dave P is offline
Administrator
 
Join Date: Dec 2008
Location: Cheshire
Posts: 22,576
Default

another thing you should do (according to the BMW assist mechanic who sorted out my last flat battery) is to reset the electric windows by opening fully then closing them fully as this resets the closing memory.
__________________
Reply With Quote
  #18  
Old 06-02-2012, 01:44 PM
issproking issproking is offline
Senior Member
 
Join Date: Dec 2008
Posts: 340
Default

Well, another winter is here and after deciding to again put mine off the road I went to start it yesterday and seems the battery has gone again.

Got a Bosch silver one last year and its been spot on for starting since.

Since in storage from November last year I've been starting it every couple of weeks and letting it run for about 30mins, each time its started no problem. I suppose letting it run doesnt properly charge the battery and that with the recent cold spell has probably meant I havent been as lucky this time.

Obviously after what happened the last time I'm certainly not going to jump start using the battery terminals but to save having to push it out the garage etc I am just going to take the battery out and get my dad to charge it using his charger then put it back in.

I take it that should be a safe enough method? I'm pretty paranoid now with this and dont want to fork out for another ECU!
Reply With Quote
  #19  
Old 06-02-2012, 03:24 PM
Dave P's Avatar
Dave P Dave P is offline
Administrator
 
Join Date: Dec 2008
Location: Cheshire
Posts: 22,576
Default

Quote:
Originally Posted by issproking View Post
Well, another winter is here and after deciding to again put mine off the road I went to start it yesterday and seems the battery has gone again.

Got a Bosch silver one last year and its been spot on for starting since.

Since in storage from November last year I've been starting it every couple of weeks and letting it run for about 30mins, each time its started no problem. I suppose letting it run doesnt properly charge the battery and that with the recent cold spell has probably meant I havent been as lucky this time.

Obviously after what happened the last time I'm certainly not going to jump start using the battery terminals but to save having to push it out the garage etc I am just going to take the battery out and get my dad to charge it using his charger then put it back in.

I take it that should be a safe enough method? I'm pretty paranoid now with this and dont want to fork out for another ECU!

charging the battery out of the car should be fine, if you have mains power in your garage it would be worth investing in a trickle charger?
__________________
Reply With Quote
  #20  
Old 06-02-2012, 03:34 PM
indy indy is offline
Senior Member
 
Join Date: Aug 2009
Posts: 4,351
Default

i think you are too paranoid now

have jump started plenty of cars in the past! and never had any lasting issues.

yes ive experienced with the modern BMW's (and others) they have a few electrical faults and lights on the dash, these should usually sort themselves out once the car has been driven with a working battery, but if not, a simple fault code read/clearing can sort it all out.

the errors are usually thrown up just because of low battery power! nothing to worry about and its perfectly normal with cars that have all the extra features........ blablabla

S50 MC shouldnt have any show up at all!
__________________

Click here to email me
Reply With Quote
Reply

Tags
trickle charger

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 Off

Forum Jump


All times are GMT. The time now is 12:38 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2018, vBulletin Solutions, Inc.