My alternator bit the dust today so before I replace with OEM I wanted to ask you all a couple questions:
What is the output on an OEM alt?
I don't have any additional current draws right now, but I'd like the replacement to be able to handle a little extra stress for when I do add some things. What I'd like to add in the future:
Stereo system. Nothing crazy, 4 channel and a sub (~700 RMS ~2000 Peak)
Power inverter. Also nothing crazy, ~2000 watts
Off road lights. all LED so I'm thinking not a big draw there either.
Winch. Not sure what kind of juice these pull but I would be getting a 10/12kLb model.
I'm not going to be running the stereo at full blast while charging an air compressor and pulling myself out of a ditch at the same time so I don't need 5000 watts on tap, I'm just looking for a ballpark for what might be a good range to run this stuff.
I've heard good things about Green Machine alts.
does anyone have good experience with another brand or have general recommendations for me?

 

A large winch will use a lot of power.

Not quite sure definitively what the amperage is on a Discovery 1 alternator but the range seems to be 100a to 120a across brands

See here, 100 and 120 version
https://www.roversnorth.com/Land-Rover-Parts/615

Your current alternator if in good shape should be fine for winch, lights. Power inverter and stereo... no clue. One hopes you won't be pulling semi tractors out of ditches with your light bar on while blasting hannah montana and charging laptops in the car....

 

Thanks! but I'll do whatever I wan't while listening to hanna montana

I noticed that the 100 vs the 120 amp options you linked have different pulley diameters. Should I be getting a different length belt to accommodate for this?

EDIT: they're 52 mm and 67 mm

 

Magneti Marelli OEM outputs 100 Amps. One from a 95.5 through 98 GEMS P38 outputs 120 Amps.

There was a time when Mean Green supported Rovers, not anymore, I think they where 140 Amps (someone will correct me, I'm sure of it).....

 

I too went down this rabbit hole and ended up just replacing it with OEM - the failure rate of the 120amp mods (this is not to be confused with the RR which was factory 120) was fairly high from what I turned up.

You could always just get a repair shop to put new bearing and brushes in - or do it yourself. I tried but the bearing was seized to the shaft.

 

So does this mean that the RR alt will be a direct fit on the D1 in 96?

 

I dont know I never got that far - I think I found a real good deal on a OEM and just went with that

 

update:
The RR alternator is a direct fit on the D1 in 96, but the higher output may (it just did on mine) blow the 100A alternator fuse.
The higher output alt from rockauto lasted me about a month before it overheated and died. ~100 city miles. it wasn't even on there long enough to get dirty..

I've seen other people say these things crap out because of the positioning in relation to the fan? apparently they get bathed in super heated air which leads to premature failure. So in that vein, I'm currently on the lookout for an upper fan shroud (mine was MIA when purchased) hoping that will help some.
Has anyone tried making a heat shield for the alt? That will be my next move if I keep burning through these things.

 

That's odd being that it is so high in the bay and right behind a fan, it should be adequately cooled unless dirty.

 

I run the 120 amp off a p38 with gems engine, dont remember if i swapped pullys