Just a quick question- I have a smart charger do I really have to disconnect the battery to charge it.

 

I have just charged it and disconnected it- Lots of warning lights came on . I stopped the engine and restarted it and they went out. All is normal now. Is this usual. 

No you don't need to disconnect the battery - it's better if you don't as changing the battery state of charge will disrupt the cars battery management system view of the battery state and possibly upset start/stop and load shedding.

 

Just connect the charger to the battery positive terminal and the tag on the chassis where the battery connects to (NOT the battery negative terminal).