I’ve recently changed my Superb and my current car hasn’t yet triggered the stop-start function. 
 

I’m quite surprised about this as my outgoing car (same model) tended to stop at junctions most of the time, no matter the weather. 
 

Could it be that the previous owner disabled it using an OBD reader or does suggest the car’s battery charge is low? It says that it’s using a lot of electrical power when I go through the settings though I don’t know why it would say that - I’m not using it differently to before. 

Poor battery is always a consideration. It was for me. Once changed problem fixed. I did a cranking test in advance and the voltage drop was more than recommended. I think anything below 10v is considered bad but i'm sure others can advise.

43 minutes ago, bigman1976 said:

Could it be that the previous owner disabled it using an OBD reader or does suggest the car’s battery charge is low?

Yes and yes.

 

You could probably get a free battery test from a fast fit place, on the understanding that you buy the battery from them if it needs replacing.