A3 battery charging/voltage issues.

pantha

Registered User
I need some input/advice,

The Car:
2006 A3 8P 2.0 TFSI (BWA) 6sp man Quattro.

Having battery/voltage problems.

Heres how it unfolded:
1. I Left the car parked for 2 weeks.
2. When i got back, the car started fine, and I drove it for a whole day no problems.
3. A day later, I went to start it, it cranked half a turn then made the typical "starter relay" clicking noise.
4. Check battery voltage: 11.5v and the indicator window on the battery is green (electrolyte is fine)
5. Charged battery.
6. New voltage. 12.3v
7. Start car.
8. Voltage now stable at 13.5v
9. Rev car, voltage up to about 14v.

It says charge voltage on the battery is 14.8v (I think, not able to check now)

So.... Is it a battery gone bad? (Dropped an internal cell)

Or... Is it my voltage regulator has/is failing??

Or... Something else?

Help please?
 

Geraldy212

Sportback owner
Seems that the battery had been very much discharged when you left it parked. What I would suggest is that you put it on a charger over night
to make sure it is fully charged. Then take it to a battery shop and ask them to do a 'Load Test'. That will show-up a dying cell.
However, if the battery is five years or over, it is probably time to replace it with a new one. Good luck.
 

pantha

Registered User
Sounds reasonable...

But shouldn't the alternator be puting out 14.5v or thereabouts?

Even if the battery is a little low?

(I had it charging for about 4-5 hrs on a 7 stage charger and it had reached the "float" stage when I took it off the charge)
 

bentwenty

Registered User
Sounds reasonable...

But shouldn't the alternator be puting out 14.5v or thereabouts?

Even if the battery is a little low?

(I had it charging for about 4-5 hrs on a 7 stage charger and it had reached the "float" stage when I took it off the charge)
The alternator on my 03 2.0TDi BKD makes 14.4v at idle.
I don't know what the lower limit is for it though...
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
The charging voltage from the alternator does seem low, typically you would be looking for 14-14.4V when the engine is running depending on the load at the time.
If the battery is original then it's 8 years old so past it's prime and if it has dropped a cell the alternator may not be able to make that voltage up to the typical charging voltage.

Karl.
 

pantha

Registered User
The charging voltage from the alternator does seem low, typically you would be looking for 14-14.4V when the engine is running depending on the load at the time.
If the battery is original then it's 8 years old so past it's prime and if it has dropped a cell the alternator may not be able to make that voltage up to the typical charging voltage.

Karl.

Well, i guess theres a point there, time for a new battery, regardless.

Is there a way to confirm this before I buy a battery? Just to be sure it's only the battery?

Because it will save me 2 trips if I need a new alternator regulator too.
 

pantha

Registered User
Update:
I charged the battery, disconnected from the car, and left it for a day or 2... the voltage went from a healthy approx. 12.5v to a LOW 10.2v without even being connected to anything.

So, I'm buying a new battery. (More about this below)

The charging voltage from the alternator does seem low, typically you would be looking for 14-14.4V when the engine is running depending on the load at the time.
Karl.


On the back of my Alternator, it states:
VALEO
06F 903 023 C
TG14C011
140A
14V

So shouldn't I be getting just under 14V out of the alternator anyway? not ABOVE 14v?

And now... which battery... I've narrowed it down to these 2 batteries:

Optima Red Top 35
720CCA
44Ah
Req'd Alternator charging: 13.65 - 15.0v

Optima Yellow Top D35
650CCA
48Ah
Req'd Alternator charging: 13.3 - 15.0v

I'm leaning towards the yellow top, as BOTH batteries are well and truly enough in terms of CCA and Ah required for the car, but the Yellow top is a DEEP CYCLE and can take an accidental draining every now and then and bounce back with minimal damage.

The only concern now is... Is my regulator going to output enough voltage to charge it?

It was only putting out 13.5v with the BAD battery attached. Was this because the BAD battery has dropped a cell, and the Regulator cannot get back to 14v? (I think it went up to 13.8v or thereabouts when i revved it)

So if it has a GOOD battery attached, it should be more like 14v output???
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
Looked at the Optima batteries, the red top is a good battery for instantaneous current draw due to the construction hence the good CCA rating but overall capacity is 70% of the Varta battery above.

http://www.tayna.co.uk/Optima-Red-Top-35R-35-720-8020-164-P7480.html

Also they are pretty expensive and only have a 2yr warranty. In a standard car application I would take the Varta every time.
You are starting a 2.0 petrol engine a battery rated 610 CCA such as the Varta is plenty.

Karl.
 

bentwenty

Registered User
Update:
I charged the battery, disconnected from the car, and left it for a day or 2... the voltage went from a healthy approx. 12.5v to a LOW 10.2v without even being connected to anything.

So, I'm buying a new battery. (More about this below)




On the back of my Alternator, it states:
VALEO
06F 903 023 C
TG14C011
140A
14V

So shouldn't I be getting just under 14V out of the alternator anyway? not ABOVE 14v?

And now... which battery... I've narrowed it down to these 2 batteries:

Optima Red Top 35
720CCA
44Ah
Req'd Alternator charging: 13.65 - 15.0v

Optima Yellow Top D35
650CCA
48Ah
Req'd Alternator charging: 13.3 - 15.0v

I'm leaning towards the yellow top, as BOTH batteries are well and truly enough in terms of CCA and Ah required for the car, but the Yellow top is a DEEP CYCLE and can take an accidental draining every now and then and bounce back with minimal damage.

The only concern now is... Is my regulator going to output enough voltage to charge it?

It was only putting out 13.5v with the BAD battery attached. Was this because the BAD battery has dropped a cell, and the Regulator cannot get back to 14v? (I think it went up to 13.8v or thereabouts when i revved it)

So if it has a GOOD battery attached, it should be more like 14v output???
May be worth having a look here http://www.batterymegastore.co.uk/
Both myself and friends have bought batteries from them and found them very good. All the batteries you get when you put your reg in exceed manufacturers spec, and come with a 4 or 5 year warranty.
 

pantha

Registered User
Thanks for the input... I have no idea what the minimum specs are for the A3 battery. So Im only guessing what I need based on what WAS in the car. (the specs: VW 7 50 73 and TL 825 06 mean nothing to me and I can't find what they are?)

Also, I'm Australia Based. But It seems I can source a Varta D15 here. will look into it tomorrow. (It's 9pm sunday right now)
 

Sayam

Well-Known Member
VCDS Map User
Nevermind deep cycle/Optima batteries you need a Varta or Bosch (rebranded Varta) that exceeds OEM specs and you're good to go

If you have a large music system you may want to consider AGM batteries but if not then forget the Optima too. Varta is the one you need
 

Sayam

Well-Known Member
VCDS Map User
As said buddy the original battery should say it's specs on it

If not go to a local motor factor/parts shop they should be able to advise using your VIN and/or registration
 

pantha

Registered User
Managed to get a Varta D15.
Got it for AUD$165.00

Picking it up tommorow. (they had to order it in)

Will keep you posted.
 

pantha

Registered User
As Promised. The SOLUTION!

I picked up the battery today and fitted it.

Unlike the old battery that was 12.3v after a charge with the trickle charger, then when put in the car and started up, the voltage across the battery terminals went up to about 13.5v. (and fluctuated up a little with revs)

the NEW battery, has a resting voltage of 12.5 or there abouts (I cant remember, but it was 12 something) and when I started the car, the voltage across the terminals is now a healthy 14.08v. (as what it says on the regulator on the back of the alternator)

So, in the end, it was a stuffed battery!

Happy days, and I hope that if this problem happens to anyone else, that they come across this and it saves them a bit of stuffing around!

Thanks for the help everyone!!
 

bentwenty

Registered User
As Promised. The SOLUTION!

I picked up the battery today and fitted it.

Unlike the old battery that was 12.3v after a charge with the trickle charger, then when put in the car and started up, the voltage across the battery terminals went up to about 13.5v. (and fluctuated up a little with revs)

the NEW battery, has a resting voltage of 12.5 or there abouts (I cant remember, but it was 12 something) and when I started the car, the voltage across the terminals is now a healthy 14.08v. (as what it says on the regulator on the back of the alternator)

So, in the end, it was a stuffed battery!

Happy days, and I hope that if this problem happens to anyone else, that they come across this and it saves them a bit of stuffing around!

Thanks for the help everyone!!
Great! Glad you solved it! I wish my battery drain issue was this simple! I'm a month in with it and I still don't know what's wrong!
 

pantha

Registered User
Great! Glad you solved it! I wish my battery drain issue was this simple! I'm a month in with it and I still don't know what's wrong!

Thanks mate!

I went down the path of pulling fuses one-by-one to see if i had a current draw issue. (it was 300mA when everything locked up) BUT... in saying that, i remember reading somewhere, that the car, will draw that current for up to 15mins then drop down to ****** all. this is just the on-board system "shutting down" after the car is locked.

I never got as far as testing that... but it might be worth try for you, if you can rig up the multimeter to be connected and have the leads from the multimeter come up out from under the bonnet so that when everything is closed and locked, you can still see the reading on the meter.

Then see what the reading is after 15mins or so?
 

bentwenty

Registered User
Thanks mate!

I went down the path of pulling fuses one-by-one to see if i had a current draw issue. (it was 300mA when everything locked up) BUT... in saying that, i remember reading somewhere, that the car, will draw that current for up to 15mins then drop down to ****** all. this is just the on-board system "shutting down" after the car is locked.

I never got as far as testing that... but it might be worth try for you, if you can rig up the multimeter to be connected and have the leads from the multimeter come up out from under the bonnet so that when everything is closed and locked, you can still see the reading on the meter.

Then see what the reading is after 15mins or so?
I've done exactly that, 300mA is normal, I have 1.2 -1.4A.
This is what is happening with it http://www.audi-sport.net/xf/thread...4a-with-car-locked.234123/page-2#post-2347843
 
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