Starter / charger

What power do you need to fire up a 300TDi with a flat battery? I need a new battery charger and I'm thinking of getting one of the starter/chargers. There are a wide range of power outputs so don't want to get one that is incapable of starting the car.

when I clamp metered the old 2 1/4 diesel, the charger I had was chucking out 400 amps.
it only just started it with a pretty flat knackered battery.
depends how long you leave it charging first and at what rate.
usually I put it on 30 amps and have a smoky, then use the high current.
(mine is home made, btw)