Onan 5500K Generator Questions.

[vonzoog]

I currently have a Momentum with the standard 5500K generator. My previous toy hauler, a Keystone Raptor, also had the exact same generator. Both of these RVs where/are stored in a pole building and are plugged into a 20amp shore power to keep the battery charged.

The following would happen when "exercising" the generator once every three weeks. On the Raptor, with the shore line 20amp still connected, starting the generator would trip the GF circuits in the pole building. On the Momentum starting the generator with the shore line 20amp still connected has no effect and everything works. Now my two questions.

1st: Was the transfer switch in the Raptor not functioning properly and causing the GF tripping or could it have been something else?

2nd: I have gotten in a habit (because of the Raptor) of unplugging the shore line 20amp before I exercise the generator. Is this necessary and a smart thing to or is it something I shouldn't have to do?

Thanks,

[D2Reid]

I am mostly ignorant on how such things work, so I disconnect shore power before starting the generator. BSTS

[carnolddsm]

Doesn’t hurt to disconnect first, however the ATS prevents cross connecting. The ATS is a break before make box. In other words one power source is disconnected before the other power source is made active.

[vonzoog]

Okay, that all makes sense. So does anyone have an opinion why it was tripping the ground fault on my previous toy hauler.

And to make sure I am clear, in theory there is no harm in leaving shore line 20amp connected when starting and using the generator?

[bigjaike]

Okay, that all makes sense. So does anyone have an opinion why it was tripping the ground fault on my previous toy hauler.

And to make sure I am clear, in theory there is no harm in leaving shore line 20amp connected when starting and using the generator?

I would only have a guess in why you other trailer tripped the GFCI, maybe the gen had a weak or open ground / neutral. As far as exercising the gen on your current trailer I would look at the following web site and follow the recommendations from Onan.

I think it would be best to unhook the power cord to make sure that your ATS shifts to the gen and does not stay on the shore power.

This is the section from the Onan manual.

"Exercising Your Generator It may seem surprising that “not” using a machine could cause performance problems, but with RV generators that’s exactly the case. Regular “exercise” is an important part of keeping your generator healthy. Lack of exercise can cause moisture build-up and fuel system degradation that make it run poorly. In fact, in as little as 30 days, the fuel in gasoline-powered generators can begin to gum and varnish the fuel system. Fuel varnishing results in hard starting and surging. (A surging generator never settles at a stable operating speed.) To prevent such problems, it is recommended to run gasoline generators at a minimum of 50 percent capacity (2000-watts, or one air conditioner for a 4000-watt set) for two hours once every four weeks. This is necessary to help keep moving parts lubricated, expel moisture and control fuel varnishing in the carburetor. A long two-hour exercise period is preferable to several short periods. While traveling, this can be accomplished by running the air conditioning. If you own a diesel generator, regular exercising can help reduce internal condensation and helps keep seals lubricated."

web site

https://cdn.ltvdns.com/leisurevans.c...r-Handbook.pdf