Generator - no 120 VAC

[Want a B]

Generator - no 120 VAC

2008 Bornfree. I’m the second owner. The manuals the first owner passed on implies coach has a Onan generator, it has a Generac QP-40G with 10 hours runtime.

I bought the Bornfree in 2020. I was suspicious of the generator because of the low hours. Generator doesn’t look “new” or any visible signs of being replaced. Generator started easily and ran smooth, with and without a load on it (disconnected from shore power). All is good.

Winter. I used compressed air to blow out the water lines. RV antifreeze down the drains. Bornfree connected to shore power for 12 VDC battery maintenance.

January. Unplugged Bornfree from shore power. Start generator and let warm up before turning on the AC and an electric space heater. Ran generator for an hour before turning off the AC, space heater and last the generator.

February. Same procedure as January.

March. Same procedure as January and February EXCEPT I don’t remember if I unplugged shore power before or after I started the generator. No 120 VAC in the Bornfree! 120 VAC outlets, convention oven and AC have no power.

I flip the 30 AMP breaker on the generator on and off. I flipped all of the coach circuit breakers on and off. Still no 120 VAC from the generator. The only GFI I find is in the main 120 VAC/12 VDC power panel on the circuit breaker labels “120 Outlets.

If the Bornfree is plugged into shore power all of the 120 VAC devices have power. That rules out the coach’s circuit breakers and the GFI.

I traced the shore power wiring to a metal box behind the 120 VAC/12 VDC electrical panel. I trace the generator wiring to the same metal box that is behind 120 VAC/12 VDC electrical panel. Metal box is a 120 VAC power transfer switch? Several blind shots with the iPhone gives me a picture of the metal box label and model number. It is a transfer switch! For $125 I have a replacement ordered.

The transfer switch is bolted to the back side of the 120 VAC/12 VDC power panel. Kitchen cabinet drawers and the 120 VAC/12VDC power panel are removed to allow access to the transfer switch. Just enough wiring slack and luck to make the change. If I had help to keep the power panel steady (shorting out) I would checked for 120 VAC before putting it all back together. I didn’t have help so I did check VAC. While I had the power panel wring exposed I check for loose connections and for any signs of overheated wiring, none was found.

I read that this generator has a fused “exciter” circuit that provides that provides power to the coils to enable the generator of 120 VDC. Check the fuse with an Ohm meter, Fuse is good. For grins and giggles I tried the YouTube trick of using a corded electrical hand-drill to “re-excite” the generator with no luck.

The 30 AMP main circuit breaker on the generator doesn’t “click” when I flip it on/off. For $39 I ordered a new circuit breaker. Installed the new breaker this morning. Removed the old breaker from the mounting panel and installed the new breaker. Removed the two wires from the left side of the old breaker and transferred them to the left side of the new breaker (yes I have the new breaker mounted in the correct orientation). Then I transfer the one wire form the right side of the old to the new breaker. While I have the mounting panel off I checked for loose wiring and signs of overheated wiring, finding none and bolted the panel back onto the generator. Flip the new breaker on/off a few times and left it in the on position. Turned the generator and and…no 120 VAC.

Unless this Newbie is missing something obvious to y’all, I’ve come to the conclusion it must be the generator’s main circuit board that is at fault. I have no idea where the main circuit board is hidden within the generator and assuming the generator will have to be removed form the Bornfree to replace the circuit board. This I am not willing to do. The few times I’ve dry camp the battery power was sufficient. 5 or so years down the road when I’m ready to sell, I’d like to have the generator working for the new owners.

And yes, when I have reliable help available I’ll do what I should have done in the first place. Use a multi-meter to check where there is and isn’t 120 VAC to actually find the problem instead of guessing.

[Bertiboo]

As a geeky engineering type, I find in my own posts that I get way too detailed and put too much of that detail in one post, and then wonder why I get few responses. Sorry but I think that you might be going down that same rabbit hole. Can you distill your issue into a smaller question? When you say no 120 vac where are you measuring it, in each instance? If you have a multimeter, are you measuring at genset output, at the transfer switch, in the unit at an outlet? Give us a bit more to go on to try to help,

[Want a B]

Originally Posted by Bertiboo

As a geeky engineering type, I find in my own posts that I get way too detailed and put too much of that detail in one post, and then wonder why I get few responses. Sorry but I think that you might be going down that same rabbit hole. Can you distill your issue into a smaller question? When you say no 120 vac where are you measuring it, in each instance? If you have a multimeter, are you measuring at genset output, at the transfer switch, in the unit at an outlet? Give us a bit more to go on to try to help,

I was more telling a story than asking for help. Here's the short version:

Generac QP-40G generator - no 120 VAC

In January and February I ran the generator utilizing the AC and an electric space heater as a load.

March. Generater starts but this time the 120 VAC outlets, convention oven and AC have no power.

Replaced the Shore power/generator power transfer switch and the 30 AMP main breaker on the generator. Still no power to the 120 VAC oultets, AC or convention oven.

If the RV is plugged into shore power all of the 120 VAC devices have power.

Generator has a fused “exciter” circuit that provides the power to the coils to enable the generator of 120 VDC. Check the fuse with an Ohm meter, Fuse is good.

Unless this Newbie is missing something obvious to y’all, I’ve come to the conclusion it must be the generator’s main circuit board that is at fault.

[mkguitar]

manual or automatic transfer switch ?


fused or breaker?


I'd start at the transfer switch and work back to the genny


you say you checked the genny's own breaker?


mike

[Want a B]

Originally Posted by mkguitar

manual or automatic transfer switch ?

fused or breaker?

I'd start at the transfer switch and work back to the genny

you say you checked the genny's own breaker?

mike

Automatic transfer switch.

What circuit are you asking is fused or breaker?

Generator main breaker tested good, I replaced it with a new one while I had it exposed for testing.

[Bertiboo]

Yes. Knowing now that the missing 120vac is at the outlets and appliances. I would work backwards with a multimeter or test light: Input to breaker panel from transfer switch. Output from transfer switch, input to transfer switch, and as you’ve said output for genset board. Remembering as you expose connectors that you must take great care not to touch or to short across poles while the genset is running or shore power connected.

[rowiebowie]

My Onan 2800QG has a breaker on the generator inself that can trip. Do you have a service manual for your genny and have you read the trouble-shooting tips?