Terminals on this alternator

[SteveK]

My alternator has a positive terminal on right side of regulator and negative on left. The main to battery on same pos terminal. Seems like a one wire ALT?

1) Is this regulator considered external?
2) what are the 3 unused terminals at bottom?

There are no markings, this is a 12V ALT that puts out 60A~, but it looks the same as up to 160A and several in between. Was Leece, then Prestolite, now obsolete so hard to find info.

 

[twistedtree]

Looks like a main positive outlet that goes to your battery, or maybe the starter and then the battery. The small black wire on the opposite side neg would be the neg side of the regulator which is the thing in the middle that's round on the bottom and straight on the top. The small red wire to the positive is the pos for the regulator. The main DC negative is through the frame and engine chassis.


So this is an internally regulated alternator with a frame ground/negative.

 

[SteveK]

Thanks TT, what I suspected. What about the three bottom terminals. Are they even active in all the various ALT or just easier to mass produce. What would they be for?

 

[twistedtree]

Those are likely the three stator windings before they go through the rectifier. Older applications often use one of them for an rpm indicator since it's an AC signal that is proportional the engine RPM. Newer engines have more accurate RPM sensors right on the engine. They are also useful test points.