I have been having problems with my generator for some time. I have come to the conclusion that the windings in the gen part are bad. Why you ask? I have 12vDC going to the start solenoid on the battery side but on the other side only 4vDC and it cranks real slow and will suck a fresh battery dry in no time. I have pulled it out of the motor home and have torn it down to the heads. All looked fine. Even lightly sanded the collector ring and checked the brushes all looked good. So, what else could it be?
Larry, I check the ground strap the other day,washed it, got all grease and dirt off and ground the gen to battery by means of a cable still same problem.
Paul...
It is off or on, buto the contacts pit. You are drawing a lot of amps through it, eventually it gets so bad it won't pass 12 volts because of the pitting. If you only have 4 volts on the generator side, it is most likely bad.
One more way check- pull the cables off the solenoid, actuate it, check the resistance. It should be 0 ohms or very close. If it is bad it will be open.
I did check the selonoid with the cables off the oppsite side of the battery and had 12 volts through, so that puts me back to the generator series field which I beleive has a bad winding. Also I took one plug out and it cranked twice as fast, has good compression but not enough power to crank fast enough, to much going to ground and from what I hear that is a synptom of a bad winding. If I am wrong please let me know.
Most equiptment uses ford type solinoids they mount to either a fire wall or something else that is metal and is grounded. Inside of it is a coil winding .12 volts excites the coil windings that are gouunded it produces a magnetic feild the draws a puck on the end of the puck there is a washer that makes contact between the two large post which completes the circut.After many terminal conections the washer wears out. and the conection wears out. I'm not saying this is your problem. but check it out because it is a heck of alot cheaper than new generator windings .The newer onans are not to expensive but most shops will tell you that the older ones are better units.
If you have 12 volts on the battery side of the solenoid and 4 on the starter side, it has to be the solenoid. If the windings were bad, and the solenoid good, it would show 4 volts all the way back to the battery. When the solenoid is closed it is a short, everything on the circuit should show the same voltage. If you are loosing voltage at one point, that is your problem.
I don't know if this is helpful to you- but i went around with my alternator not putting 14+ volts to the chassis battery--and ended up replacing the battery isolator. It was fried. When i took it out of the loop and checked the voltage, I had the sum voltage of my batteries (coach and chassis) coming out of the alternator. I replaced it and the voltage is back to correct levels.
Also I had noticed on my previous trip that my tv/vcr would not play tapes. It worked on and off....it now works just fine. Seems it was not getting enough voltage. The isolator came from Pep Boys, and was 3o bucks.
Short of putting a wrench across the battery terminal and running for your life, it is nearly impossible to drag a battery down to 4 volts. Most batteries are 'dead' at 10.5 volts. After cranking the generator until the battery died, have you checked the voltage at the battery? How about the battery cable, it would become extremely hot from discharging the battery so quickly, probably to the point of melting insulation.
When the solenoid contacts pit, they become very high resistance. Everything in the system can be A+, but the resistance will not let current pass. It will seem like the battery is dead, but the voltage has only dropped to a point where it can no longer overcome the resistance of the contacts. You are showing the voltage drop at the solenoid. Try jumping around the solenoid, straight to the starter.
Here is the latest on the generator problem as of tonight. Two weeks ago when the Tennessee legislature decided to shut down the government I had a few days off from school so I went full steam working on the generator. After I took the generator out of the motorhome I could tell that the windings were or at least one was bad and most of my cranking power was going to ground. With that info I called Onan here in Nashville and after talking to them for a while they say "Oh you have a bad winding that thing is older thatn dirt, it would not be cost effective to fix the winding buy a new one." (throw away society)
I found a guy that will do a winding for $150.00 or so.
I hope to hear from him in the next few days, so pray pray pray.
Paul,
I had a similar response from the Onan factory once that left me feeling a bit uneasy.
After spending 250.- plus on a new circuit board on my previous MH, I called them about a new carburator. After telling me that they are not available, the guy told me to use it for a boat anchor.
The original onans are good generators and worth fixing if possible.
If I ever get a new one, it will be a water cooled Honda.
Good luck on your generator!
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