Onan Generator

[JimEasTexas]

Can you run/exercise the generator when plugged into shore power?

[lwmcguir]

Absolutely, although I still shut any high amp loads before doing so

I have generators that sit for a year between usage, so I don't worry about the monthly exercise cycle one bit and never have

Generators exposed to high humidity might be another issue though and above all keep halogens away from them

[dkoldman]

Originally Posted by JimEasTexas

Can you run/exercise the generator when plugged into shore power?

Yes, For most coaches; the ATS will switch to generator to supply power to the coach even when Shore is connected.

In my case, I can't
My coach is wired where if my AGS sees shorepower is available (ON); it will not start the genny unless I do a workaround; and if genny is running, and I connect to shorepower, it will automatically shut down the genny. These are all settings within Onan EC-30 AGS

Originally Posted by lwmcguir

I have generators that sit for a year between usage, so I don't worry about the monthly exercise cycle one bit and never have

I don't worry about or do exercises either, but I use my generator year around a lot more than what the exercising normally calls for. I do worry I do not use my generator more. I think there is false perception of what the gas may cost when running genny?

If I knew I did not need for an entire year, I would follow the winterize / storage procedures in Onan Manual and not exercise either.

[DavidEM]

You can but as alluded to above, when the generator finishes its start up cycle and turns power on, the coach's ATS will automatically transfer the shore power loads to the generator. This may put an immediate high load on the generator which isn't good. You should let the generator slowly add loads over a few minutes to give it a chance to warm up first.

The above assumes that the ATS gives the generator priority, which is the case on most.

David

[JimEasTexas]

Thanks all appreciate the good information.

[Pillbox]

Turn off the breaker by the genny start button first. No breaker on, no pass through voltage.
Terry

[16ACE27]

Originally Posted by Pillbox

Turn off the breaker by the genny start button first. No breaker on, no pass through voltage.
Terry

No pass through voltage = no load.
No load = no exercise.

[Pillbox]

I run it to warm oil, change it, run, check turn off.
I’m to fat to exercise, so is my genny.
I was answering the run part.

[16ACE27]

Originally Posted by Pillbox

I run it to warm oil, change it, run, check turn off.
I’m to fat to exercise, so is my genny.
I was answering the run part.

You don't need to open the generator breaker to run it with SP connected as answered earlier in the thread.

[Bob Nodine]

The main thing to remember when energizing the transfer switch via the generator while shore power is connected is to make sure the air conditioners are off before starting the generator. Turn them on after the generator is running. The reason for this is because the compressors in the air conditioners are high current inductive loads. When current is flowing in an inductor and the current source is interrupted the voltage will increase in an attempt to keep the current flowing. The contacts of the transfer switch is what is interrupting the current flow if the air conditioners are running the compressors at the time of the transfer. That will arc the contacts of the transfer switch and soon lead to failure of the transfer switch.

[Jimbo56]

Originally Posted by Pillbox

Turn off the breaker by the genny start button first. No breaker on, no pass through voltage.
Terry

Don’t have a breaker by the generator start button. I make sure everything is off. Unplug from SP. Start generator. Wait till I hear the tone indicating power changeover. Then turn AC back on. Turn TV on. Watch 3 or 4 innings (2 beers worth). Then do reverse to go back to SP. But, to each his own. With 2 ac power sources at same time, I can only see a potential problem.

[JimEasTexas]

Thanks good stuff.

[Pete'sMH]

Originally Posted by Jimbo56

Don’t have a breaker by the generator start button. I make sure everything is off. Unplug from SP. Start generator. Wait till I hear the tone indicating power changeover. Then turn AC back on. Turn TV on. Watch 3 or 4 innings (2 beers worth). Then do reverse to go back to SP. But, to each his own. With 2 ac power sources at same time, I can only see a potential problem.

If you have an Onan generator you DO have a breaker by the start button on the generator. Exercising the generator under load at least once a month is a good idea whether you do it or not. And so is exercising the ATS by “letting” it do its job at least once a year.

[dkoldman]

Originally Posted by Jimbo56

Don’t have a breaker by the generator start button. I make sure everything is off. Unplug from SP. Start generator. Wait till I hear the tone indicating power changeover. Then turn AC back on. Turn TV on. Watch 3 or 4 innings (2 beers worth). Then do reverse to go back to SP. But, to each his own. With 2 ac power sources at same time, I can only see a potential problem.

I believe he is talking the outside start button, and the breakers that are actually on physical generator. But I didn't follow the logic of just wanting to run the engine to warm oil.

Originally Posted by Bob Nodine

The main thing to remember when energizing the transfer switch via the generator while shore power is connected is to make sure the air conditioners are off before starting the generator. Turn them on after the generator is running. The reason for this is because the compressors in the air conditioners are high current inductive loads. When current is flowing in an inductor and the current source is interrupted the voltage will increase in an attempt to keep the current flowing. The contacts of the transfer switch is what is interrupting the current flow if the air conditioners are running the compressors at the time of the transfer. That will arc the contacts of the transfer switch and soon lead to failure of the transfer switch.

I agree with statements in principal, but fail to understand why the need or manual focus. Don't all coaches with ATS have some type of power management systems that control this automatically? My AC units and whatever are ON all the time, but no matter they do not start up immediately upon ATS being energized. I site one very purpose of AGS as my source of confusion. If you want to maintain coach at 75 degrees; the thermostat is set at 75, but both units are set to AUTO ON, but if coach is 70 degrees and batteries are fine AGS has genny off. Coach heats up to 76 degrees genny will start, ACs do NOT immediately start. And when they do, they stagger the loads; Front AC followed by Rear AC. This is true even if I manually start the Generator. Further, if I am running the Genny and connect the shorepower, the AGS will automatically shut down the genny forcing the ATS to activate shorepower. What am I missing, because if the automation is doing damage, so be it, I will not worry about it. I use AGS 98% of the time, almost 4 years.

[Jimbo56]

Originally Posted by dkoldman

I believe he is talking the outside start button, and the breakers that are actually on physical generator. But I didn't follow the logic of just wanting to run the engine to warm oil.



I agree with statements in principal, but fail to understand why the need or manual focus. Don't all coaches with ATS have some type of power management systems that control this automatically? My AC units and whatever are ON all the time, but no matter they do not start up immediately upon ATS being energized. I site one very purpose of AGS as my source of confusion. If you want to maintain coach at 75 degrees; the thermostat is set at 75, but both units are set to AUTO ON, but if coach is 70 degrees and batteries are fine AGS has genny off. Coach heats up to 76 degrees genny will start, ACs do NOT immediately start. And when they do, they stagger the loads; Front AC followed by Rear AC. This is true even if I manually start the Generator. Further, if I am running the Genny and connect the shorepower, the AGS will automatically shut down the genny forcing the ATS to activate shorepower. What am I missing, because if the automation is doing damage, so be it, I will not worry about it. I use AGS 98% of the time, almost 4 years.

I don’t have AGS (automatic generator start). I’m the guy who has to prime it for a count to 60 before it will start. Would probably burn the starter up if I had AGS.

[dkoldman]

Originally Posted by Jimbo56

I don’t have AGS (automatic generator start). I’m the guy who has to prime it for a count to 60 before it will start. Would probably burn the starter up if I had AGS.

I thought you owned a Thor? IMO what makes Thor great is their feature rich coaches. Some will slam them for quality issues but may lose the fact that for the most part they got some of everything. TMC is #1 for a reason, but those reasons are quite often ignored on this site. I don't see the bashing as much on other sites. I think it may be relate the fact that most Thor owners know a value when they see it, but after purchase they don't understand or keep moving the gray lines of what they failed to detect before purchase and what the warranty actually means.

Anyway, the coach I bought DID NOT come with AGS. It was hard for me; because I was in love with the Firefly. I heard the bad, but didn't care, at the time a Firefly was a must have.

When I did buy my SOB, the 1st thing I did or bought, after the Camco Sewer hoses and Camco Toilet paper; both of which I NEVER use today; was the Onan EC-30.

I cleverly paid a local dealer for this install; so my 1st experience with them was positive not requesting warranty work; which they frown on if you did not buy from them.

They have Wireless EC-30 today that work with Smartphone, but I don't think I want or need that. The EC-30 is easy add on, but in your case it is the power management system you may or may not have that sheds the loads is what you may consider as well. The EC-30 is the closest thing to a Text Toy for me, I love and use all the time.

FWIW; if I know I will turn off the Genny intentionally (manually), I do shut off both ACs if they are on, but when we drive the AGS is turning genny on and off all day and both ACs are always ON. I just have trouble believing that is a problem.

[Bob Nodine]

Originally Posted by dkoldman

I believe he is talking the outside start button, and the breakers that are actually on physical generator. But I didn't follow the logic of just wanting to run the engine to warm oil.



I agree with statements in principal, but fail to understand why the need or manual focus. Don't all coaches with ATS have some type of power management systems that control this automatically? My AC units and whatever are ON all the time, but no matter they do not start up immediately upon ATS being energized. I site one very purpose of AGS as my source of confusion. If you want to maintain coach at 75 degrees; the thermostat is set at 75, but both units are set to AUTO ON, but if coach is 70 degrees and batteries are fine AGS has genny off. Coach heats up to 76 degrees genny will start, ACs do NOT immediately start. And when they do, they stagger the loads; Front AC followed by Rear AC. This is true even if I manually start the Generator. Further, if I am running the Genny and connect the shorepower, the AGS will automatically shut down the genny forcing the ATS to activate shorepower. What am I missing, because if the automation is doing damage, so be it, I will not worry about it. I use AGS 98% of the time, almost 4 years.

You are not understanding the problem. The problem is caused if you are connected to shore power and the air conditioners are already running and the compressor is running drawing high current. Under those conditions if you turn on the generator when the generator output becomes live the transfer switch will energize breaking the connection from the shore power plug. A principle in physics is that an inductor wants to keep current flowing and the voltage will increase across the contacts that disrupts that current. When this happens the contacts arc and burn. Do this a few times and the contacts usually fail. All I was pointing out was to guard against this happening you should make sure the air conditioners are off when you start the generator while connect to shore power.

Energy management systems or softstart devices have nothing to do with this and cannot prevent the problem if the compressor is running when the current is disrupted.

[dkoldman]

Originally Posted by Bob Nodine

You are not understanding the problem. The problem is caused if you are connected to shore power and the air conditioners are already running and the compressor is running drawing high current. Under those conditions if you turn on the generator when the generator output becomes live the transfer switch will energize breaking the connection from the shore power plug. A principle in physics is that an inductor wants to keep current flowing and the voltage will increase across the contacts that disrupts that current. When this happens the contacts arc and burn. Do this a few times and the contacts usually fail. All I was pointing out was to guard against this happening you should make sure the air conditioners are off when you start the generator while connect to shore power.

Energy management systems or softstart devices have nothing to do with this and cannot prevent the problem if the compressor is running when the current is disrupted.

Simply put for what you stated above highlighted in Red, my Generator will not start. If the generator knows you have shore power why would you want to start the Generator?

My other point was my coach was not equipped with AGS, so I installed one after the fact to make full use of the automation of various systems

I follow what you are stating, that is why I started by saying "I agree with statements in principal"; but perhaps you did not follow how some coaches are wired in conjunction with EMS, Compressors and AGS.

Regardless and even without AGS, when my genny starts there is a delay BEFORE the EMS supplies power to the ACs and they stagger the loads. To my knowledge, I don't have a way to override; and make the ACs draw load immediately for genny? FWIW; I don't have any Soft Start type system.

Yes a true interruption is a interruption, i.e. if I lose shore power and ACs are running and power is loss it is IMMEDIATE. There is nothing anyone can do to prevent that unless you have knowledge when a interruption will occur? When this occurs and very very rare, my genny will start and supply power. It will warm and the EMS helps control.

It is also why I always have my AGS ON when driving when AC is needed because if it gets too cold, the thermostats will shut down the compressors and the one thermostat that controls the genny will get a call to shut down the genny.

[Mo_Mike]

I go ahead and turn off the breaker for shore power before starting my generator. Yes, the ATS is designed to handle this, however, I already had a sloppily wired ATS almost catch fire and lose one leg to my AC when I first bought it, so I look at it as a couple of minutes to possibly save a lot of expense.

Also, if you have a gas generator (ONAN) I would make sure to start and run it every two to three weeks. This is to keep the fuel fresh in the carburetor and not evaporate and clog the jets. I ran mine once a month to two months for the first two years I owned my coach and ended up forking out 800.00 for a new carb (CUMMINS) since I didnt want to void the three year factory warranty. Cummins said they now charge 1600 for the carb replacement.

[JimEasTexas]

Thanks [emoji106]