The engine is all in the Ka and running well, but i think i have overlooked something... the alternator.

After a few minutes driving, the battery just dies and the car starts spluttering. Charge it back up, and its fine again - untill it runs low again obviously.

Are there any simple tests you can do to test if the Alt is working tidy?

Only think i know to try now is put a multi meter on te blue wire from the Alt to see if theres 12volts going through it, which would show on the escort dash (i havent yet wired that intot he ka).