Naughtie

Hey all -- I know I'm about due for a battery replacement as my car is hitting the 5 year mark.

Based on the threads I've browsed I may or may not need VCDS and / or a BEM code, but my question is this:

Can't I just hook up another car to my Audi's jump points, and keep the current flowing while I swap in the new battery? Presto, the car will never know something's changed! (Yes?)

audi8k

The reason for "coding" in a new battery is to inform the battery management system that it has a new battery.

Naughtie

I understand that, but the only reason the system would "care" that I installed a new battery is if it had detected a bad or dying battery, correct? My battery is still working well, just five years old.

Again, I'm not sure that this is anything I need to concern myself with -- the forum posts seem mixed. My neighbor, on the other hand, found his BMW in limp mode after a batter swap and had to jump through some similar hoops.

treilley

I swapped the battery in my 2010 after getting a few low battery warnings(7 year old battery). I did not have to code it and it is working fine for 2 months now.

uberwgn

Naughtie, change the battery and don't fret. I think the only that was lost in my '11 A4 was the odometer reading.

audi8k

I don't know how important it is and if replacing with identical battery I would assume that the battery charging control unit will eventually adapt to the charging level of the new battery but how long it will take and how far from optimal charging the new battery will see in the meantime might be of concern. The control unit knowledge of the battery charging level is said to be a parameter that controls the charging voltage.

This is quoted from Audi Selfstudy document 287:
Battery replacement -----------------------------
On battery replacement, the new battery
must be adapted by way of the diagnosis
tester. The menu item "Battery manager
encoding" is provided in the assisted faultfinding
routine in the list of systems with selfdiagnosis
capability in the battery manager.
The battery serial number has to be entered
for encoding. This is marked on the battery.
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