technical E90 Battery Troubles

[LYFGP]

Hi gents and ladies.

I've been noticing my car has a bit of a hard start the past few weeks, so i'm guessing it is the battery that needs to be replaced now.
The current battery has lasted me 4 years.

As soon as I got to the office this morning, The battery light came up on the dash in red (CC-ID 213)

Do I just go and replace the battery or first get a diagnosis to check what's wrong?

Vehicle: 2010 E90 320d Msport Auto LCI

 

[ptmatjila]

Besides having your battery checked, it might be a good idea to also have your alternator checked.

 

[LYFGP]

Quick update.
Alternator is Fcked. It's currently at a workshop being sorted.