"NOT GEN" dash light MCI 102a3

[Chopper Scott]

My purpose was to mention that with my setup and the one wire alternator that the light shows up as "not gen" even as the volt gauge shows 28 volts. It is turned off by the air presssure that enabled the air tensioning cylinder for the old gen and not by any charge now. I really have no use for it anymore with a dash mounted volt gauge. The 1 wire alt needs a lot of rpm to activate it and I had my concerns. Where I got the alt they do something internally with the wiring to get it to activate quicker. Later

[Sean]

     I  added a 24 volt 1 wire alternator on our MC-8 and still use the No Gen light. Light comes on when master switch is turned on and goes out as soon as engine starts (and generator starts charging).

So if I understand this correctly, you have a light that tells you the master switch is on, but the engine is off.  (Where did you connect the low side of the light?).  However, that does not tell you the alternator is working properly, unless you have some way to measure the voltage.

I did have to add an IGN wire on the alternator to get it to charge without revving the engine.

Not sure I understand where you added this wire.  If it is a true "one wire" alternator, it does not have any extra terminals -- it literally has exactly one post, which is used for charging, field, and regulation.  Or am I missing something?

-Sean
http://ourodyssey.blogspot.com

[Jerry32]

I know when I had my solar panels connected to the bus batteries thaat the not gen light would be on while driving so what it can tell you that charging voltage is high so regulator cuts out?? Jerry

[JackConrad]

Not sure I understand where you added this wire.  If it is a true "one wire" alternator, it does not have any extra terminals -- it literally has exactly one post, which is used for charging, field, and regulation.  Or am I missing something?
-Sean
http://ourodyssey.blogspot.com

Sean,
  I guess I misled you in referring to my alternator as a 1 wire. I should have referred to it as a 24 volt alternator with a built in regulator (I consider alternators with built in regulators as "1 wire" alternators). My alternator has 3 terminals (BAT, Ign, and R).  Sorry for the confusion.  
   The dash light is the OEM NO GEN light and functions as it did with the OEM alternator operating from the relay controled by the R terminal on the alternator.  Jack

[Sean]

I know when I had my solar panels connected to the bus batteries thaat the not gen light would be on while driving so what it can tell you that charging voltage is high so regulator cuts out??

Yes, this is why I keep saying that alternate charging sources are the #1 suspect here.  If you have a second charge source connected to the batteries, and that source brings the voltage up beyond the regulator's set point, then the regulator will turn the alternator field off completely.  This will cause the Relay terminal voltage to drop to zero, and the Not Gen light to come on, because, literally, the alternator will be spinning but "Not Generating."

   I guess I misled you in referring to my alternator as a 1 wire. I should have referred to it as a 24 volt alternator with a built in regulator (I consider alternators with built in regulators as "1 wire" alternators). My alternator has 3 terminals (BAT, Ign, and R). 

Right, and I can see how you would make the Not Gen light work with that setup.  But, in my book, a "one-wire" is literally that -- it has a single terminal post.  I would call what you have an "internally regulated" alternator.  I'm assuming Scott has just what he said: a one-wire, which means he would have no way to re-connect the Not Gen light to make it work.

-Sean
http://ourodyssey.blogspot.com

[Chopper Scott]

Correct Sean. I only have one single positive wire on my alternator that I hooked into the main wire that originally fed the generator. The other wires are obsolete basically now and with such I have no method of making the light work properly now. I already had a 24 volt gauge that I mounted in the dash anyways. The one wire alternator excites itself at anything above an idle and I can live with that. Later