Exercise genny while on shore power?

[J-R]

New to on board generators. Parked for the winter with 50 amp service, and it's time to exercise the genny. Do I have to disconnect first?

2006 Bounder, Onan 5500, ATS

[way2roll]

Not just hearsay, I've heard of real cases of things getting screwed up when running the genny and shore power at the same time. Sure the ATS is supposed to work and prevent a catastrophe. But as we all know too well, RV parts fail all the time. Given the 30 seconds (and that's being generous) it takes to unplug or turn off the pedestal breaker, why wouldn't you? Only takes one time for the ATS to not behave appropriately and you've created a mess that's not only a real inconvenience but very costly.

[folivier]

Not all transfer switches are set up the same way. Some give priority to the generator, others give priority to shore power. You need to know which way yours is set up.
Mine is shore power priority but my Newell had generator priority.
Yes always turn off all high loads such as air conditioner or heater before switching or plugging/unplugging. This will protect your transfer switch from arcing and damaging the contacts.

[MFL]

pianotuna wrote:
Hi,

Unplug.

Exerise.

Replug.

30 minutes @ 50% load, after a 3 minute warm up.

This is how I do it too. Always best to be safe.

Jerry

[gbopp]

I always disconnect from shore power before starting the generator.
Just in case there is a malfunction with the ATS, it removes all doubt.

[cavie]

No need to unplug anything. That is why they call it an " AN AUTOMATIC TRANSFER WITCH". IT IS DESIGNED TO DO JUST THAT. It is not a decoration.

[MrWizard]

"Transfer switch shouldgive priority to the generator"


Now that is the stickler, the word should , if it doesn't , bad things could happen, that is why you unplug first

[time2roll]

No reason the unplug. Transfer switch should give priority to the generator to run the RV. Load it up with a couple space heaters or some other significant load.

[pianotuna]

Hi,

Unplug.

Exerise.

Replug.

30 minutes @ 50% load, after a 3 minute warm up.

[J-R]

Thanks for the replies.

Janss wrote:
To be absolutely sure nothing bad happens, I would unplug shore power first (or turn off breaker). I have an automatic transfer switch. One time I turned on the generator while plugged into shore power...don't remember if a load was on it, but I think not...and the situation burned my EMS that was plugged into shore receptacle.

Well, this what I expected to get for an answer, but thought I'd check with people that know. I'll have to do it when the DW is out for a walk instead of watching tv, and then reset some clocks and reboot the satellite receiver.
Glad you mentioned the EMS! Guess I'll unplug from that too when I flip the breaker. I was just worried about arcing the contacts in the ATS.

[Janss]

To be absolutely sure nothing bad happens, I would unplug shore power first (or turn off breaker). I have an automatic transfer switch. One time I turned on the generator while plugged into shore power...don't remember if a load was on it, but I think not...and the situation burned my EMS that was plugged into shore receptacle.

[dieseltruckdriv]

Bobbo wrote:
Depends. You need to exercise it once a month for 2 hours with at least 50% load. Can you get a 50% load on it while still plugged into shore power? When I had an on-board genny, I used the A/C in the summer and a pair of space heaters in the winter, but I had to unplug from shore power for that.

Why two hours? I am not being snarky, I am being sincere.

My brother works on electric motors and said to make sure to give the windings a regular workout, but he said it doesn't need to be a large load, but they do need a load. I have been doing monthly runs on my Hondas for over 10 years, and running them 10 or 15 minutes, enough to warm up the oil good and give them a load.

[Dutch_12078]

The ATS will switch the RV from shorepower to the generator, but that should not be done with any significant loads present. I recommend flipping the park stanchion breaker off before starting the generator. Make sure the park rules allow running the generator at that time though.

[Lwiddis]

Exercise with a load.

[Bobbo]

Depends. You need to exercise it once a month for 2 hours with at least 50% load. Can you get a 50% load on it while still plugged into shore power? When I had an on-board genny, I used the A/C in the summer and a pair of space heaters in the winter, but I had to unplug from shore power for that.