Hi, after an unexpected trip to hospital, the A6 stood for 4 weeks and will not crank over.

As it is 8 years old I have ordered a new battery Varta Silver / Varta Batteries / Batteries by Application

I have VCDS to recode the type & serial

Should I just disconnect the old battery and fit the new one or connect another power source to the cables to avoid and data loss?

Any advice ?

thanks