2019 Kuga auto start stop not working

[Greenfaldo]

Evening all, picked up the Kuga in the week but can’t get the start stop to work. I’m used to the system on my BMW so not a novice with it. On the display when the u come to a stand the @ comes up with a line through and it’s out of gear foot off the clutch but the engine doesn’t cut out, the question is do u need the brake pedal depressed or should it work without? In the BMW u don’t need the brake pressed. 
also if during the journey I’ve pressed the @ button and turned it off do I need to turn the engine off again to cancel it, I’ve pressed the button so it’s turned back on but I’m clutching at straws for the reason. 
thanks in advance. 
mike

[Meta55]

Not enough charge in the battery. Day to day mines doesn’t work but if I go to visit the family about 170 miles away, it works again. Ford have a really stupid charging system that barely put enough in the battery then stops charging until needed again, to get more mpg out the car.