Classic Audi Community General Chat » Smart Alternators

Reply
 
Thread Tools Display Modes
Old 16-03-18, 11:23 AM   #1
Ringmaster
Senior Member
Classic Audi Club Member
 
Ringmaster's Avatar
 
Join Date: Apr 2008
Posts: 1,000
Default Smart Alternators

Peeps,

I was chatting to a mate of mine about an on-going problem he's been having with his battery. He's been told by his dealer (Alfa Romeo) that these new 'Smart' alternators only charge when there is no input from the accelerator. i.e., they only charge when idling or coasting, so there'is a strong possibility one's battery never gets well charged....

Has anyone else heard this?
Ringmaster is offline   Reply With Quote
Old 16-03-18, 12:06 PM   #2
vagdream
Grown up member
 
Join Date: Jul 2015
Location: Llandudno Junction
Posts: 68
Default

I understood it was part of the fuel saving benefits of the 'coasting' mode of some current vehicles.
vagdream is offline   Reply With Quote
Old 16-03-18, 12:38 PM   #3
John.
4 ring whore!
Classic Audi Club Member
 
John.'s Avatar
 
Join Date: Mar 2011
Location: Scottish Borders.
Posts: 6,497
Default

Been common-place for a while now.....if you're belting along at 70 mph with no extra consumables switched on....does the battery need charging, no.
Alternator will start charging it again when voltage drops below a prescribed amount.
Yet another ECU on the modern car
John. is offline   Reply With Quote
Old 16-03-18, 03:06 PM   #4
Colin Aitchison
Grown up member
Classic Audi Club Member
 
Colin Aitchison's Avatar
 
Join Date: Dec 2013
Location: 5 miles from Bathgate Central Scotland
Posts: 954
Default

I had a 2008 BMW that only charged when coasting or braking, all to do with MPG saving.
Colin Aitchison is offline   Reply With Quote
Old 16-03-18, 05:07 PM   #5
Ringmaster
Senior Member
Classic Audi Club Member
 
Ringmaster's Avatar
 
Join Date: Apr 2008
Posts: 1,000
Default

Seems more of a threat to reliability
Ringmaster is offline   Reply With Quote
Old 16-03-18, 08:42 PM   #6
msh
4 ring whore!
 
msh's Avatar
 
Join Date: Jun 2008
Location: Rucava, Latvija
Posts: 3,803
Default

That's not alternator but charge controller, separate control unit that controls charging of the battery. Dunno which was first B series audi to have it, B6 or B7, in C series first was C6. It also requires that battery intended for that to be bough, with some specific code, which is used when adapting new battery to controller - if old battery will be replaced by new one without adaptation, controller won't charge it fully...
msh is offline   Reply With Quote
Old 16-03-18, 09:01 PM   #7
John.
4 ring whore!
Classic Audi Club Member
 
John.'s Avatar
 
Join Date: Mar 2011
Location: Scottish Borders.
Posts: 6,497
Default

Quote:
Originally Posted by msh View Post
That's not alternator but charge controller, separate control unit that controls charging of the battery. Dunno which was first B series audi to have it, B6 or B7, in C series first was C6. It also requires that battery intended for that to be bough, with some specific code, which is used when adapting new battery to controller - if old battery will be replaced by new one without adaptation, controller won't charge it fully...
As internal resistance of the battery increases with age the ECU will change the charging characteristics....... so yes the alternator ECU needs to know when a new battery has been fitted.

Makes me glad to drive the older stuff, better for the environment too
John. is offline   Reply With Quote
Old 17-03-18, 12:50 AM   #8
theschmallfella
Grown up member
Classic Audi Club Member
 
theschmallfella's Avatar
 
Join Date: Sep 2011
Location: (That) London
Posts: 728
Default

Quote:
Originally Posted by msh View Post
That's not alternator but charge controller, separate control unit that controls charging of the battery. Dunno which was first B series audi to have it, B6 or B7, in C series first was C6. It also requires that battery intended for that to be bough, with some specific code, which is used when adapting new battery to controller - if old battery will be replaced by new one without adaptation, controller won't charge it fully...
What?! I never knew this, and the battery in the A6 is being a ball ache for the last month or so, and I was thinking that it was nackered. So, are we saying that if I were to leave the A6 idling for 10 minutes on the drive it would charge the battery better than a long drive on the motorway? Am I picking this up right?
theschmallfella is offline   Reply With Quote
Old 17-03-18, 06:49 AM   #9
John.
4 ring whore!
Classic Audi Club Member
 
John.'s Avatar
 
Join Date: Mar 2011
Location: Scottish Borders.
Posts: 6,497
Default

Quote:
Originally Posted by theschmallfella View Post
So, are we saying that if I were to leave the A6 idling for 10 minutes on the drive it would charge the battery better than a long drive on the motorway? Am I picking this up right?
No.

On the negative terminal* (if it has smart charging) there is a sensor which tells the ECU how many amps the battery is taking. Only if it is fully charged (and in good condition- the ECU will decide) and therefor taking very little charge, will the car be running solely off the battery.

The above is my take on it, TBH I'm not really worried about how it works just as long as it stays working!


*A cover on the negative terminal with picture showing not to attach a jump lead is a sign that it has smart charging.
John. is offline   Reply With Quote
Old 17-03-18, 11:16 AM   #10
SwallownAmazon
Grown up member
Classic Audi Club Member
 
SwallownAmazon's Avatar
 
Join Date: Jun 2017
Location: Tonbridge, Kent
Posts: 238
Default

That explains why my E38 BMW 740 Sport has jump lead terminals under the bonnet when the battery is in the boot and not easy to get at. I'll start a thread on the 7 Series forum and find out some more as my alternator seems to be working overtime with the characteristic whistle as though it's working hard. That'll be a bugger if it ever goes wrong - it's buried deep in the front of the V of the engine as it's cooled by water at around 88 dec C. How hot can the bloody thing get ?!?
SwallownAmazon is offline   Reply With Quote
Reply

Bookmarks

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 11:20 AM.

Powered by vBulletin®
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright ©2007-2008 Classic Audi | Site by Roadrunna