Turns out it does, if the alternator doesn't detect the bulb on the clocks go out then it won't charge. The breakdown guy ran a cable from my live terminal to a bit on the alternator with a bulb, it lit up and then with igntion the bulb went out and the alternator started charging again. Only problem is I have to do it every time I start the car cause it resets when you stop it. New day, new lesson. I better sort my bloody clocks out