New Battery


Registered User
The battery in my 2007 A6 Allroad keeps discharging ( I think I have an air leak but need a full battery to test)
Looking at the battery it is not a OEM it has no BEM code and does not match the code in VCDS.
The OEM should be a Varta size 353L x 175W x 190H (019 size).
From a google search I find the larger 020 size 394L x 175W x 190H will fit. Seems like room in boot.
Has any one fitted a 020 size AGM battery in this age of car ? or should I stick with a wet battery 019 size?



Well-Known Member
Gold Supporter
AGMs are used in start/stop applications. Do you have that on your Allroad? If not, I’m not sure it’s worth the additional cost.

You will need the battery coded. (See other similar posts)

You mention an air leak as the possible cause. As far as I’m aware an air leak won’t drain the battery, as the air pump is not operational when the ignition is switched off (don’t quote me - I’m assuming that’s the case like most cars!). Besides which, if it is the cause - replacing the battery won’t fix that, and will only result in a flat battery again.

Are there any other fault codes in VCDS? Have you checked for any issues with charging, or current drain when everything is switched off?


Registered User
Thank you for quick reply.
No I dont't have stop start but I believe the AGM is a more heavy duty battery.
Fault codes are battery regul. Stage 1 3 and 5 - intermittent
If the car is left at level 1 2 or 3 it drops over time, but on 4 it says up till the battery goes low ( I need to test a little more with a new battery) I suspect rear air bags are leaking.
I have managed to answer one question just took some details of the installed battery and it is the larger 020 so they do fit !