Installing hour meter on Onan 7.5 quiet diesel

[Carl Boger]

This past year I had to put a new inverter in my onan 7.5qd generator so I thought this would be a good time to add the optional hour meter.  I ordered a hour meter that was reported to fit and it is a bit different from the diagram in my manual.  The back of the hour meter has a sticker that is labeled AC 110V over ~250V.  It also has 2 male type connectors for 12 volt female type leads. 
The wiring diagram in my installation manual shows the hour meter wiring up to 12 volts from remote control connector plug.  Positive lead from the F terminal and negative from the A terminal.

The hour meter is not marked for positive or negative.  I tried to test it out by hooking to the battery positive and negative.  It did not move or register hours with the wires in either position, so 12 volts does not seem to run this hour meter.

Has anyone ever seen a hour meter that runs off 110?  I am sure I can find a source to hook it up to, but don't want to fry it either.  I am guessing that the hot and neutral go to the 2 post and it runs the hours up in either configuration. 

The hour meter physically fits the knockout where the hour meter goes.

Any insight to getting this working would be appreciated!

Thanks Carl

[Steve Huber Co-Admin]

Carl,
The hour meter should work when 120C AC (hot and neutral) are applied to the terminals. Polarity should not be an issue.
Steve

[Fred Brooks]

   Carl,
Not real sure where you purchased that meter but Onan uses a 12 volt meter in remote locations. The white 4 wire harness goes to the switch and meter. I do not have the schematic in front of me but the 2 wires that go to the meter are the 12 volt positive and the ground. The 12 volt positive only becomes activated when the generator is running. The 12 volt meter is also polarity sensitive and will not work if positive and negative is reversed. The correct meter also registers 1/10 of an hour on the right side of the meter (white numbers) and there is also wheel that rotates when operational to show it is running so you don't have to wait 6 minutes to see the digit move.
  I am not sure where you would mount the gauge you have unless it is on the gen itself so it receives dedicated 110 volts only from the generator. By code the switch you have has to be located in an approved metal enclosure so you don't get zapped if you accidently touch it when energized.
  Please advise on the 7.5 kw model you have and I will look up the correct wiring. Hope this helps.....Fred

[Carl Boger]

I have the HDKAJ,  I just have the generic wiring diagram that came with the motorhome.  It even states it is typical.  If its not going to work I will send it back and order another one from someone else.  Just had not seen this before, Thanks Carl

[Fred Brooks]

   Carl, where are you installing the meter and is the Onan wire harness already there? Is there a meter already mounted on the generator? Fred

[Fred Brooks]

   Carl, You are correct. Once you get the correct meter, "F" is the positive connection and "A" is the negative connection. I am going to look in my spare parts cabinet. I think I have a spare meter. Fred

[Carl Boger]

Thanks Fred,

No meter currently there, The one I got does not work at all so its garbage.  Not sure if the harness is already there, I was trying to test the meter before going onto the install in case something like this happened.  It was new in the box, but I have been down that road before.  I have wired in hour meters for boats and other small motors so was not expecting any trouble, but better safe than sorry.  Thanks Again, if you have a spare i would be interested in it.

[Fred Brooks]

  Hi Carl,
   I think the 120 volt meter you have is for maintenance of "run" time on a dedicated device of some nature. Here is a pic of the meter I have. It is one I removed from something a long time ago but had no hours logged on it. I ran it on a 9volt battery for 7 minutes just to make sure it worked yesterday. The cut-out dimensions of the meter are 1 3/8" wide. 7/8" high, and 2" deep. If you message or E-mail me with your address, I'll send it to you. Blessings, Fred

[Carl Boger]

Sent you a pm

[Fred Brooks]

  Hi Carl,
  The hour meter was sent today, you will have it on Monday. I'll get back with you on the step slide next week. Have a great week-end! Fred