Whats the highest output alternator that I can physically fit on my 200Tdi Disco with it's "V" belt? I saw 100A conversions using a 300Tdi alt but I want more amps.
Twin motor front winch and an 12,000lb rear winch and around 1,500W of aux lighting 
Looking at having twin optima batts for the winching on a VSR that should handle 400A, failing that I will have to look at second al set up to go with my two aircon pumps on the aux belt.
Looking at having twin optima batts for the winching on a VSR that should handle 400A, failing that I will have to look at second al set up to go with my two aircon pumps on the aux belt.
If it were me......
First thing I'd do is a proper load analysis, consider how much of that auxiliary lighting is going to be used concurrently. 1,500W is a fair amount, at a 'nominal' 13.8v that's around 110A. Are they all facing forward? Is LED an option? LED is higher cost, but you can get the same or higher lux for the same or less power consumed.
Similarly, the winches are (imo) a burst load. They shouldn't really be considered a 'running' load - just have enough battery capacity for them. Unless you want to use the winches for motive power and use the engine as a generator
I wouldn't even consider fannying around with a split-charge or anything of that ilk, run some or all of the lighting and the winches off a secondary alternator and battery bank (twin or even triple properly matched deep cycle batteries). If you want the lights 'linked' to your original headlights (i.e. spotlights relayed from main beam) it's easy to switch a different power source.
As to the original question of "which alternator", well the answer to that is simple:
One that will fit and has the voltage output you want.
I'm not using 'fit' in the sense of having the same bolt pattern and pulley, I'm using 'fit' in that it will physically go in the hole you can find... Make brackets, change pulleys, swap the fan if it's not the rotation you want - none of it is exactly a 'challenge'.
First thing I'd do is a proper load analysis, consider how much of that auxiliary lighting is going to be used concurrently. 1,500W is a fair amount, at a 'nominal' 13.8v that's around 110A. Are they all facing forward? Is LED an option? LED is higher cost, but you can get the same or higher lux for the same or less power consumed.
Similarly, the winches are (imo) a burst load. They shouldn't really be considered a 'running' load - just have enough battery capacity for them. Unless you want to use the winches for motive power and use the engine as a generator
I wouldn't even consider fannying around with a split-charge or anything of that ilk, run some or all of the lighting and the winches off a secondary alternator and battery bank (twin or even triple properly matched deep cycle batteries). If you want the lights 'linked' to your original headlights (i.e. spotlights relayed from main beam) it's easy to switch a different power source.
As to the original question of "which alternator", well the answer to that is simple:
One that will fit and has the voltage output you want.
I'm not using 'fit' in the sense of having the same bolt pattern and pulley, I'm using 'fit' in that it will physically go in the hole you can find... Make brackets, change pulleys, swap the fan if it's not the rotation you want - none of it is exactly a 'challenge'.
