I’ve been given one of these Halfords in car cooler fridge coolbox 12v FD-28B-12, and it has a 24v (cigarette lighter end) lead rather than the standard 12v lead. I have a 24v socket in my wagon, is this safe to use. The coolbox says it is 12v/24v, if I plug this into the 24v socket will it burn out, as it will be in constant use all week.