Battery/alternator issues

[Dangerousdean]

Just got red message on dash saying visit workshop, fitted new battery when I got the car as the old one was completely dead, I do have a mb2 icarsoft reader but am unsure where to look for faults? Also could it be something other than alternator?

 

[Dangerousdean]

Also if it makes any difference it’s not idling smoothly anymore either so I’m thinking it’s the regulator