Lets talk about alternators!

Ok the early XJ used a delco alt from 84 to what 90? Then in 91 went to the Mitshi unit till 96 or was it 97? What came after that? Also, if my alt. is not charging is it the alt? Guy at the local alt shop told me that there isn't a reg in the mitshi units that it is controled by the computer? Anyone know about this? Also if the reg is in the computer how do they turn these things up?

As 5-90 notes, the 91-up models using the Mitsu. alternator have the regulator in the ECU, and we'd better hope those things are good, because that is indeed a very expensive bit of integration! Because an alternator doesn't require current regulation, the voltage regulator is required only to control voltage, and that is the same whatever the alternator's current output, which explains why you can upgrade alternators without worrying about the regulator. The regulator switches current to the field, controlling its magnetism, which controls the voltage induced in the stationary windings. In order for this to work, unfortunately, the field cannot have significant residual magnetism (you couldn't regulate it then) and this means that there must always be an outside source of current to "excite" the field or it won't start generating. I don't know about special applications, but I've never run across an automotive alternator that was self-exciting. Whatever the connections and regulation, you'll need at least a smidgen of current in the battery to get it going.

Ok The post that is the ground on the alt. was busted so I jumpped it to the bottom mounting bolt. The reason I think it is not charging is b/c the other night when I went for a test drive the jeep acted funny after a few min. So I turned around and came back to the shop. When I got back I shut it off. After looking to see what was going on and finding nothing I tried to start her and she was dead! Ok so what is the proper method for testing output? Volt meter to the output post to ground? What about turning up the amp output? How is that done on these units? Local shop wants $65 to rebuild.

Voltmeter should be a good basic test. Between output and ground, or just at the battery. You should see 14 volts or more at the battery when it's running. You can't turn up the amp output of an alternator: it's always set to put out its maximum capacity. If you want more amps you need a bigger alternator.

You can probably get your stock alt. rewound when you get it rebuilt. You'll have to talk to the person doing the rebuild though.

If a local rebuilder wants $65 for it, that's not too bad. That's about what I pay at a shop I've been using for a few years, and that includes upgrading them now... I've also found that Rod's rebuilds have held up better than new parts - probably something to do with being able to look the guy in the face when you talk to him... I've always preferred that "personal touch." You can probably get a higher output unit from the local shop anyhow - most of the power parts are aftermarket in the first place. Having a Mit will probably allow you more power than my increased Delco - look at the "sport compact" market and all those stereos they use to play that Godawful racket!

5-90

Ok so $65 is not too bad but this guy was not the most friendly. I think he is one of those "I know my shit" types that is afraid of actually going the extra distance to make a customer happy. When I asked about more amps out of that unit he was like "Can't be done." So are these high output units that I see in car stereo shops and ebay actually bigger alt?

Find a different shop. My local did my Delco up (I got the case back that I took in - most of my parts are signed with an engraver from dealing with rebuilders that tried to screw me...) to about triple the output specified in OEM. No complaints here.

The parts are available to do the job, sounds like the guy just has a pole up his ...

You'd have to ship, but I can give you contact info for the shop I use here in San Jose - I've almost got him talked into rates (but he's still "on the fence" and would need some volume convincing...) EVERYTHING that comes out of his shop is run on the bench, and I've seen him build some exotic industrial and heavy equipment electrics, so he does know what he's doing...

5-90

It's a simple matter to "soup up" a Delco...All there is to it really is to install a high output stator (the fixed windings) and make sure you have a good rotor from a 12SI unit..12SI rotors are more expensive/valuable than the lower output 10SI....ans as a result a lot of "rebuilds" end up with the lower output rotor...make sure the diode pack, regulator and diode-trio are in good shape..some fresh bearings and brushes and you are good to go.

Having never seen a mitsu in a Jeep installation in person (my experience is a few years old) I wonder if it is possible to fit a delco in it's place with a little fab work????? you wouldn't need the ECM regulator if it can be done. Just a thought...I used to easily modify Chrysler alternators to replace Lucas units on old Triumph TR's...in the 70's it cost over 300 bucks to fix a lucas and even then it was as reliable as you could throw it..

I have the Delco stlye alt in my XJ built to put out 150amps. I had the shop put a smaller diameter pulley on it so it spins faster for lower rpm power output. I have 4 ga. wire between the alt and the silonoid on the fender and the same going from the silonoid to the battery. I haven't had any problems with this setup at all.

:lecture: Did you know that the 94 is not wired through the red wires in the battery bolt? There is a square metal thing (for lack of a better word) that has a round thing (ditto) that just presses on the battery bolt? Further more the alt. will not charge when it's not connected to the battery! :dunce: :twak: So I took the jeep for a spinn tonight! First tiem since Tellico! Wow that was July!