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Dragline, I am going to change the front battery. What I want to know is why is the teg going to the front battery instead of the back one which is for starting?


Don't say that too loud as it will start an argument as to which is the starting battery. lol
Clearly the VW stuff says its the rear battery but I firmly believe this is a miss print.
When my front battery went dead I could not start even using the emergency method.
I have been in a T2 with the front battery removed and it will start but still only with the emergency method.
Those are facts,.
When mine starts even with a good front battery it still draws some current from the rear battery.
I believe it uses both but the front is still the main supply.
All other Treg's use the front why would VW run cables that extra length and deal with voltage drop.
As well the front battery in a V10 is the bigger CCA battery?
But don't want to argue about just start the engine I say.


regards
Drag
 

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V10 Battery System

I just changed out my front battery...... because it wouldn't start. Battery was dead.
Everything was off. black dash, nothing, zero, nada.
when I connected a charger to the front battery, all of the dash stuff powered up
rear battery tested perfect.
car started fine on the bypass system.


I will back Drag on this, doesn't make any sense to change over both batteries just because one dies.
the starter battery may last for years. Front AGM battery, not much change out of $500, so not in any rush to change both.
given that there are two batteries, and taking into account the difference in duty cycles, the chances of them both failing at the same time is slim.
my two cents worth on that subject.


will throw some oil on the fire.... file from VW self study program.>:)


http://www.volkspage.net/technik/ssp/ssp/SSP_298_d1.pdf


Page 21 clearly shows the starter battery at the rear and the consumer battery under the seat.

after a quick read through, I'm reasonably sure that if the front battery is flat, the car won't start because the startup consumers ( engine control unit) are supplied from the on board power supply battery.
if the front battery is flat, the consumer items are supplied from the starter battery via the bypass system.
in normal condition, the front battery initiates the start, but the actual starter current is supplied from the rear battery.
Seems that if the starter battery is flat, the power supply battery is switched in and does the start.
I'm guessing this may be why the power supply battery is bigger. in the last case, this power supply battery has to supply the startup load as well as all of the consumer load.




Ian
 

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front battery needs power to control the intelligent systems. If it's flat the car's brain is basically dead and it won't start with a fully charged rear battery.

If the rear battery is flat the brain (powered by front) will know this and use the front battery to start the car.
 

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front battery needs power to control the intelligent systems. If it's flat the car's brain is basically dead and it won't start with a fully charged rear battery.

If the rear battery is flat the brain (powered by front) will know this and use the front battery to start the car.



First quote is somewhat incorrect.
I have personally removed the front battery on a T2 V10 and then been able to start it with the emergency key procedure.
My T1 will not do this


Quote from the VW self study that also says the rear battery is the starter battery.


There are four different conditions that can be


detected before the engine is started depending


on the charge status of the batteries:


- Onboard power supply and starter battery


charged


- Onboard power supply battery discharged,


starter battery charged


- Onboard power supply battery charged,


starter battery discharged


- Onboard power supply and starter battery


discharged


So by that doesn't matter which battery is flat a V10 will start unless both are flat.


regards
Drag


 

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Thanks for all the information and it does make sense. So now I understand why my Teg still has the orig. battery in the Trunk, even the studs holding the metal straps have black paint on them - WOW.
 

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anybody know where I can get suitable batteries around Perth?
front was showing 11.48V this morning, haven't checked the rear one yet.
 

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so I got a price on a din88 AGM battery which seamed like the H8 mentioned by the OP for the boot, cool $375 but the shop seamed to think this was for the front main battery?
thought I'd better check, the main battery under the passenger was 390mm long x 175 wide x 190 high and did not appear to be an AGM.
this looks like a DIN 100 battery, sort of thinking I should go for the bigger battery?
 

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Larger front battery will not fit in rear. Rear is AGM for more power in smaller package.
 

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Touareg V10 batteries should've been replaced by now, at least once, if not twice.
In Australia,
the trunkwell (what we call 'under deck') accessories battery can be replaced by a Varta Silver H3, ETN 600402083, 100Ah, 830 CCA.
the LHS front seat starter battery can be replaced by a Varta Silver I1, ETN 610402092, 110Ah, 920 CCA.
The +ve cable off the alternator has a habit of heating and will fry with a house battery, and DC-DC charger in a car-back carcass, if you have a fridge and a drawer setup.
It's about four hours labour to replace the cable with 8WG at the alternator and install a shunt. This will provide a proper reading at the dash voltmeter, which usually pins at 14V, but will properly read the voltage with a shunt, as without a shunt, you just get a time averaged reading.
 

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The rear battery starts the car on the V10. The front battery is for the ancillaries.
 

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thanks for that V10Touareg1, not sure what you mean by &amp 'house battery'? i put a varta din 100 AGM under the front seat. I1 varta 393x175x190h, 920CCA, 110 AH,
 

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Hi All,

Reading the VW electrical manual (the pdf that can be found on the web) my understanding is that on the V10 the underseat battery is the house battery and the rear one (under the pump up spare tyre) is the emergency starter battery, but that both are used for engine start, the rear one only taking over completely if the house battery falls below sufficient voltage to start (when you have to use the key with the left then right movement to fire up the rear one for start).

I've replaced the house, underseat, battery a couple of times on my 14 year old V10, but never had to replace the rear one. I noticed that the replaced house batteries did not seem to hold charge well, and when I mentioned this to the guys that service my car in Adelaide (AutoStudio), they advised me that when a battery is replaced the ECU has to be "told" that a new battery has been installed as the car changes the charging profile as a battery ages, and will be using an incorrect profile for the new self-installed battery.

I don't know if this is true, but they reset the ECU for me and the house battery seems to be charging, and holding charge, much better.

Regards, Mike.
 

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The rear boot/trunk battery starts the car with the front under the seat battery assisting on certain circuits.

If the rear starting battery is duff for any reason, then the front battery can provide the emergency start.

The ECU story has been told a number of times but, to my knowledge over nearly a decade, no one has ever posted the how-to . . .
 

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I had both batteries changed about 2 yrs ago. The Treg has failed to start on its own for the last 2 days. I end up having to use my wifes car to jump start it. The Treg fires right up as soon as you turn the key on with the jumper cables attached. But then over night or while sitting at my office she will die again. It did this the last time the batteries died. So I am thinking that all I need to do is replace one or both batteries.

My question is this, Once you have physically changed out the battery(s) what do you have to do? Do I need to hook up vcds and clear codes? Or can you put the new battery(s) in and just start driving? Last time I had a shop do the work and they mentioned that they ran a scan and cleared all codes after putting the new batteries in. Is this correct?

This time I am hoping to save myself some money and do it myself.

Thanks.
 

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As far as the battery charging "coding" goes...

The T1 does not have it.
The T3 seems to have it.
Most T2 (all?) don't have it.

Most Q7* (all?) have it.
Cayenne, later models require coding.

If you have it, you will have a setting in VCDS to enter a new battery Serial #. The Serial # is found on the VW battery, and it really does not mean anything to the module. All reports I have read indicates that once the module takes a serial #, then it just starts a countdown timer and the amount and the length of the charge is just numbers read out of table.

Over time, the charge is slowly decreased. The theory is that the battery has also degraded, and the reduced charge into the reduced capacity will lead to a healthier elder battery. Since no real checks of the battery capacity is being utilized, I wonder about how correct this is.

As far as I can tell, the system does not work any better or worse then the traditional charge system, but it creates nothing but trouble for the end user; making what was once the most simple of car maintenance a trip to the dealer/shop/someone with a proper VCDS setup.

*(from Ross Tech) Note: Newer Q7 models don't have an actual 61-Battery Manager but instead have the battery management as a slave under the CAN-Gateway. In these cases, installation of a new battery would require the use of Long Adaptation under 19-CAN-Gateway. Follow the onscreen instructions to enter the Part Number, Vendor, and Serial Number all as one long new value.

wiki.ross-tech.com/wiki/index.php/Battery_Replacement

forums.ross-tech.com/showthread.php?3240-Battery-Coding
 

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Have you checked for a defective door handle? The vehicle electronics are probably never going to sleep. You should check status of each door antenna. You really need VCDS where you can also "look" at each battery separately as well as log your voltage drop while starting.
 

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I just had or have the same problem with failed starts on my v-10 and stupidly changed out the starter/rear battery without having it tested first as I assumed that if it doesn't start right it should be the starter battery...
now I am going to test the front battery and if bad replace it... oh yea dealership will not take back the battery,...ugg
 
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