Onan Generator Voltage Question

[jff]

I ran my Onan Generator overnight on the 4th, the generator ran fine and there were no signs of any problem. Just by chance, in the morning I opened the door where you can control the Feed/Return to take a look at which tank I was pulling/returning from - I noticed that the volt meter for the generator was low and showed an amber light instead of the normal green. The range is from 8-18 and I think it was showing around 12 with the amber, I don't remember where it usually is when it is green (I'm thinking 14 ish). What would be the possible causes of this? fyi - the generator continued to run without any problem for about the 4-6 more hours of our weekend. I should also mention, in case it is related, that we have all new AGM batteries, installed about 60 days ago (and have been using the generator without problem since that time). Before the 4th I did check the generator Fuel filter, it was in great shape. Of course, I also checked the oil which was replaced about two weeks ago, no problem there. Any ideas?

Thanks!
Jason

 

[tobnpr]

The voltmeter is reading your alternator output- sounds like it's kaput or nearly so.
Normal output should be in the range of 13-14 volts.
Check the output with a mulitmeter to confirm. Could also be a loose belt at the alternator (?).

This is an easy fix; pull the alternator and take it in for a rebuild.

 

[jff]

Dumb question - is this an alternator inside the generator or completely seperate from the generator? I'm thinking it's unrelated to the generator itself (ie. not on Onan service call) ... wanted to verify. Thanks!

 

[tobnpr]

I don't know anything about your make/model of genset, but all generators have an alternator for charging the starting battery- just like your mains.