Alternators

[Romanrob]

8R chassis, CAHA engine code.

My alternator failed, battery collapsed, recovered from M3... Local garage and Audi West London failed to ID the fault, so I did my own research (after the same failure again).

A. Replaced the 7 yo battery. Easy job, 10mm spanner to remove -ve then +ve terminals in the boot. Battery shd be the same spec, but you need to reprogramme the battery coding, for which you need VCDS (see Ross Tech forum). In theory you need to keep some power on the terminals under the bonnet to keep memory.

2. Use VCDS and run auto scan. CAN 19 measuring blocks 14, 15, 16 will give you Generator data (18, 19, 20 for battery)

I had block 15 error in Electrical Generator status

You can remove the regulator (VR) from the back of the Valeo alternator, but Q5 is tightly packed and you have mm' s to spare. Remove negative from battery (i didn't bother with a memory saver, no ill effects). Remove live from back of alternator, and plug... Take off cage with screwdriver. M7 to remove 3 bolts, remove VR.

My brushes were gone, check out YouTube for an easy soldering job to replace...

Wasn't my brushes though, then replaced the whole VR, not that either...still got the Group 15 fault.

Just embarking on replacing the whole alternator. Again doable..but you'll need some dexterity.

-Ve disconnected. Remove timing cover. Remove 2 bolts on coolant tube (black hard plastic),  move gently sideways. Mark ribbed belt direction. Use a wrench on the tensioner to remove the belt from alt pulley only. Remove two screws, with a 13mm ratchet, on alternator bracket. Use a 19mm socket and a bolt to draw the alternator bushes out, its v easy . Bottom screw can not be fully removed, only once the bushes are withdrawn....  Audi service manual suggests tapping them out with a hammer - waste of time.... Remove the alternator from engine bay pulley first

And...Valeo and Bosch are not interchangeable...diff plug for starters.

Hope it helps

[niedzial1983]

If you replace battery with the same specification then you dont have to do any coding

[Magnet]

Hello Rob,

Now I'm sticking my toe in waters of unknown depth here, since I'm must quickly say that my personal experience with this "modern" battery technology extends to what I have read ( which I guess may or may not be right) rather than what I have experienced. As I understand it AGM batteries were developed decades ago but were not fitted to our production cars until about 10? years ago.

As such, would I be correct in assuming that your 2010 vehicle would have originally been fitted with an AGM battery when new? 

If so, by what I have read, AGM batteries must only be replaced with another AGM battery, otherwise you will c..k up the 'intelligent" charging capabilities of the alternator. i.e. you alternator will pack  up!  True or not true? Worth the risk??

Perhaps you will tell me that yours wasn't originally fitted with on of these, or it was, and you have fitted another similar, and there is no connection here between changing batteries and alternator issues. 

If so - great - and this post ( for what it is worth!) may only serve to perhaps encourage others to check up on what they have before renewing batteries.

Kind regards,

Gareth

[Romanrob]

Niedzal, maybe, maybe not... The coding relates to badged capacity, ageing, and a learned charge state. I'm pretty sure you can get away with it short term, but you may end up with an undercharged battery as a result. From what I see MMI reads 100pc at whatever state the battery is reconnected, but if the system believes you had your old 7 yo battery then it will probably not charge as it would your new one, and then under-charged batteries fail prematurely...

 

[Romanrob]

Hi Magnet, batteries not my area of expertise either... My battery wasnt AGM, so I didn't encounter this issue, but if you have stop start on your car, I don't, then i wouldnt switch types as the demands on the battery is completely different. If you do switch you'd defo have to reprogram the new type and for that you need VCDS too

[Romanrob]

The alternator kicks out 140A max, and the battery is charged at 7A or so, so I dont think your choice of battery has much of an impact on the alternator, but again, you need the energy managent system programmed right...

[Magnet]

Hello Rob,

Thanks for coming back on this. Note your point about your original battery not being an AGM but I just wonder - on a belt and bracers policy- it you were certain the battery  that was replaced was the original one fitted to the car when new. 

I would not have expected a seven year old alternator to give problems, or indeed for it to suffer battery issues quite yet, that's why I wondered if you checked what the battery specification should be, rather than was (swopped?) 

Just a thought. 

Kind regards,

Gareth. 

[Romanrob]

Thanks. The battery was a Varta, most likely Audi issue, as it has a BEM code on it, and was coded into VCDS. I cant be 100pc sure that its 7yo as we have only had it 5, but its pretty likely.

I now have a brand new identical Bosch S5, replacing a properly programmed VAG battery so no issues ( i advanced the battery serial number by one digit, so the car knows it's a new battery)
 

The alternator warning was semi-permanently on saying alternator not charging, usually triggered by the use of high demand equipment (aircon or Headlights). VCDS said electrical problem with generator, and reported an energy management shut down of the aircon etc.

Physically, when I removed the VR the brushes and slip rings were majorly worn. In addition a load test with lights and air con was only kicking out about 11v from the alternator. After a recent long journey the battery was off from 12.8v to 11v, and draining the battery at 25 A.

 

Could I rebuild the alternator etc? Maybe, but its the wife's car, and i have a day job, so I'm just buying a replacement and putting it in. The point being, if you do it yourself you save stacks on Audi labour, so can afford to bolt on a new one.

[Markku]

Hi, Romanrob & others.
I saw this conversation was a few years ago - but - checking if anybody would follow it...presenting my problem.
I have the same Q5 as Romanrod, i.e. Q5 2010 with 2,0 TDI, engine-code CAHA.
After having issues with charging, the red blinking battery symbol after the message that there is low or no charging last November I have been working on the car, not being able to drive it. Status Quo is: New battery installed, aftermarkt model battery with no BEM code - did, however code in via OBDeleven by changing one digit to trick the BEM into knowing there is a new battery. New generator installed after I first tried to replace the regulator only.

Symptoms: ( the same that were there before and after BEM coding)

Ignition off - get 12.6 - 12,7 at B+, Jump socket (the one under hood) and on battery itself.
Motor running, I get 14 - 14,5 V on B+ but I only get battery voltage (12.0 - 12.2 or lower) everywhere else, (i.e; jump socket and on the battery.)  Note: NO "battery light warning" on instrument panel, suggesting that the system believes everything i fine. I can drive the car as far as the battery carries me -There is NO battery warning light - but - battery is NOT charged...
I would like to follow the B+ down to the generator to se how far the 14 volt reach. BUT the gen. and it's connectors, are so badly situated that it is almost impossible to get a measurement cable down there without tearing everything apart - and at that point you wouldn t be able to start the car....
Has anyone tried to short-cut directly from B+ up to the jumpsocket + just to see what happens? It is all + but of course with a voltage differential. You would use a fuse inbetween?? If this were to work, and the battery get's charged I ´could drive like that. The car is my 2nd car and has high mileage...but I like it.

Anybody experienced / ascertained a bad connection at starter leading no charging-voltage up to jump-socket and further, to battery? OR is the BEM, being unhappy,  capable of completely shutting off charging?

Grateful of any input.
regards
Markku, Stockholm, Sweden

[Ddawg]

Hi Markku 

Did you get to the root course of the issue on your Q5? I have the exact same issues. Voltage dropped and car went on safe mode. The battery was 8 years old so I decided to change it. coded it to the code and all. 

The only exception in my case is at time the battery is charging. Like on the 3 or 5th start it seem to charge at 13 to 13.7 Volts. 

Thanks 

 

[alpha omega]

old post dev 3 years old.you never know though

[Magnet]

Welcome Dev,
13 to 13.7v is too low. Should be nearer to 14.5v.

Kind regards,

Gareth. 

 
 

 

[Stevey Y]

10 hours ago, Ddawg said:

Hi Markku 

Did you get to the root course of the issue on your Q5? I have the exact same issues. Voltage dropped and car went on safe mode. The battery was 8 years old so I decided to change it. coded it to the code and all. 

The only exception in my case is at time the battery is charging. Like on the 3 or 5th start it seem to charge at 13 to 13.7 Volts. 

Thanks 

 

Hi it could be the BEM module on the negative post on the battery these are quite delicate and have a history of failing on Q5/Q7.

Steve.