AC/Generator Operation

[bjboles]

Is it ok to have the AC in the on mode and then turn the generator on? Is it hard on the generator or AC unit?
For example, I'm driving the RV by myself and it starts to warm up to where the chassis AC won't keep up. Could I have the AC to the on position before leaving that way all I have to do is turn the generator on and not pull over?

[Wyatt]

The Onan manual recommends that you NOT put a high current load until the generator has warmed up, and to not shut off with any high load still on, until the generator has cooled down. I think I recall they said 10 minutes or so…

[dkoldman]

Originally Posted by bjboles

Is it ok to have the AC in the on mode and then turn the generator on? Is it hard on the generator or AC unit?
For example, I'm driving the RV by myself and it starts to warm up to where the chassis AC won't keep up. Could I have the AC to the on position before leaving that way all I have to do is turn the generator on and not pull over?

You don't say which coach, your concern is valid and yes it would be hard on the generator and not recommended by Onan, but I do this all the time in my Sunstar 29VE.

I have the Power Control System (hopefully you do too?) When I know it is going to be warm even with the DW, I will have both ACs on Auto On mode, normally the Genny is off when we are leaving. But as Coach warms up the HVAC will call the Genny to turn on. My generator runs about a minute before you can actually use any of the major appliances i.e. Fridge / ACs. Once power is on it sends power to the ACs but it goes another 2 minutes before one units fires up, the 2nd will fire up shortly there after. They both will run until until the desire temp inside is reached which will shut off the ACs. The Genset will also know that the HVAC call is no longer needed and based on how long it has been running (min runtime) it shuts itself down automatically.
It is actually pretty slick.

Even If I were to manually turn Genny On; it would do the same thing, but if ACs are running and I just turn Genny off, that is not ideal, I would manually turn the ACs off first. But I use my AGS almost all the time, even when I don't think I need. I am often amused as to when it turns itself on and why.

[be happy]

To me there are so many advantages to running the gen. all the time. Its part of our start up and shut down procedures. I make sure the AC is off before starting or stopping the gen. Let the gen run and put current to the coach then turn your ac on. As long as you have the gen on you might as well turn the frig. to AC and save propane etc.

[bjboles]

Originally Posted by dkoldman

You don't say which coach, your concern is valid and yes it would be hard on the generator and not recommended by Onan, but I do this all the time in my Sunstar 29VE.

I have the Power Control System (hopefully you do too?) When I know it is going to be warm even with the DW, I will have both ACs on Auto On mode, normally the Genny is off when we are leaving. But as Coach warms up the HVAC will call the Genny to turn on. My generator runs about a minute before you can actually use any of the major appliances i.e. Fridge / ACs. Once power is on it sends power to the ACs but it goes another 2 minutes before one units fires up, the 2nd will fire up shortly there after. They both will run until until the desire temp inside is reached which will shut off the ACs. The Genset will also know that the HVAC call is no longer needed and based on how long it has been running (min runtime) it shuts itself down automatically.
It is actually pretty slick.

Even If I were to manually turn Genny On; it would do the same thing, but if ACs are running and I just turn Genny off, that is not ideal, I would manually turn the ACs off first. But I use my AGS almost all the time, even when I don't think I need. I am often amused as to when it turns itself on and why.

My RV is a 2004 Winnebago Journey 34H. I do not have the generator auto start feature. It looks like the best practice should be to start the generator pull over and then turn the AC on. And then opposite order to shutdown.

[creativepart]

I keep the A/Cs on and then while driving when I feel the space behind getting hot while driving I just reach down to the Gen Start on the dash and start the generator.

The generator and the A/C both have delays built into them.

[deckape]

I have installed a shower curtain behind the front seats. Attaches to the private curtain hooks that are there. Cools the front area very well using the dash air. As we get into the campground, I'll start the gen . wife goes inside, I unhook the tow, get back in and start A/C's. Get to camp site and set up ,the coach is cool. Turn off A/C's and gen, then plug in . Wife then turns A/C ' s after about 10-15 minutes. Works for us.

[Morich]

In big load situations like commercail, they build in delays as a way to let the genset get going fully before loading but when looking at the size of our Rv generator loads, it seems to make less hazard.
Part of the question is due to the load making it more difficult to spin the generator and that "could" make if more difficult to start.
On our size generators, there is less danger for the starter getting too hot if the generator is starting well.

I would want to look at what my RV does in any specific situation and not try to start it with a load if it is a time when it may struggle to start. Understand that the starter does have limits to how long we want to crank as it does warm pretty quick. But in warm weather, so that the oil is also ready reasonable warm and easier for things to move, there is far less hazard than if we try to do it in cold weather and without the engine alternator running so that the combo of lower voltage plus longer cranking time can make things worse.
I think of the starter far more than I worry about the windings on the genset on our RV. On larger generators, it may take an hour to get things to full temp but our size warms much quicker as there is so little actual bulk to warm. Cool down works the same and really isn't too big worry for us.

[dkoldman]

Originally Posted by bjboles

My RV is a 2004 Winnebago Journey 34H. I do not have the generator auto start feature. It looks like the best practice should be to start the generator pull over and then turn the AC on. And then opposite order to shutdown.

Got it... I made mistake of assuming you had AGS when you stated you left AC on while driving and waiting for it to warm for to turn generator on.

In your case even if without AGS (Auto Start) I think there will be delay before start?

For test:
Set your ACs to On position with no shorepower and no generator. Make certain the ACs have not run for at least 10 minutes.

Then go start your generator. Time what happens from the moment your Generator starts.

i.e. How many secs before power is on the Fridge?
How many secs before power is on the AC#1?
How many secs before power is on the AC#2?

My guess is 2 to 3 minutes

But given when ACs are running, and you wish to shut it all down, shut down the ACs 1st before turning off the Generator.

[creativepart]

Originally Posted by Morich

Part of the question is due to the load making it more difficult to spin the generator and that "could" make if more difficult to start.

Maybe everybody else has a different Generator or maybe it's my ATS but when I start the generator there is a 30+ second delay before 110v power is delivered to the coach.

When you turn power on in my coach the microwave beeps. When we stop for lunch on the road and start the generator we wait for the beep to know when there is power to the coach.

And, when either of my A/Cs start up, they always start up in fan only mode initially and it's at least 30 sec but could be as much as a minute before the compressor kicks in.

So, I can't see how starting of the generator could be effected when the A/Cs are set to come on - with the gen power delay followed by the A/C compressor delay there really is no issue of "too big a load" when starting the generator with the A/Cs on.

[Morich]

I would expect it to vary with different Rv with different generator size and different loads involved. If it is a problem, I would also expect the right equipment built in to protect the whole package.

[powercat_ras]

Is your generator bigger than 4 KW? I suspect it is on a Journey 34K.

My experince with my Onan 4 KW is that if I forget that the thermostat is set to AC and it is calling for the AC to run when I start the generator, it is about 50-50 if the generator will carry the sudden simultaneous load of the AC and the Converter-Charger without stalling out.

With a bigger Gen if you set to only use 1 of the 2 AC chances are the generator will carry the load without stalling.

The other posters who note that it is less stress on the generator to let the generator run with the converter-charger load for a little while before adding the AC load are correct. However it likely will work , IF you have a 6 or 7 KW generator.

Another trick you could try would be to flip off the converter charger breaker in the breaker box and make sure the AC hot water mode is switched off, so the only load on the gen would be the AC unit.

[bjboles]

Originally Posted by powercat_ras

Is your generator bigger than 4 KW? I suspect it is on a Journey 34K.

My experince with my Onan 4 KW is that if I forget that the thermostat is set to AC and it is calling for the AC to run when I start the generator, it is about 50-50 if the generator will carry the sudden simultaneous load of the AC and the Converter-Charger without stalling out.

With a bigger Gen if you set to only use 1 of the 2 AC chances are the generator will carry the load without stalling.

The other posters who note that it is less stress on the generator to let the generator run with the converter-charger load for a little while before adding the AC load are correct. However it likely will work , IF you have a 6 or 7 KW generator.

Another trick you could try would be to flip off the converter charger breaker in the breaker box and make sure the AC hot water mode is switched off, so the only load on the gen would be the AC unit.

My generator is a 7500 Quiet Diesel.

[dkoldman]

I only have a 5500 Onan, and until this thread I thought they worked on same principle. We have removed the AGS as factor so we are only talking what happens when you manually start the Genset.

In my coach it is impossible for ACs to try to start at the same the genset starts.

There are two levels of protections. Everybody may not have the 1st; but should have the 2nd unless maybe it is dated coach?

When my genset is manually started, it does not feed power to the coach for full minute. That is because of PCS Power Control System. Some coaches may have similar but it basically knows the genset is sending power, but it is preventing any loads against it for 1st minute.

Then once the power is supplied everything gets power EXCEPT for both AC's. The ACs (Coleman) have built in 2 minute delays so once it get power it does not fire up until after that 2 minutes. Somehow, and I don't know how the PCS also make sure that only one AC will fire up at a time.

That is why I asked the OP to do the test. He may not experience what he is trying to prevent?

[bjboles]

I did notice when I fire up the generator from the command center there isn't power to the RV right away. That aligns with what you are saying about the built in delay.

[dkoldman]

Originally Posted by bjboles

I did notice when I fire up the generator from the command center there isn't power to the RV right away. That aligns with what you are saying about the built in delay.

A+++ Now we getting some where. That proves you have some sort of Energy Management System. You may wish to look it up to find what brand and get some documents on it. Mine is PCS. Precision Controls Systems

I put a stop watch on mine and I get 60 second delay every time. Measure to know how long?

Your next TEST is see how long of a delay do your ACs have before they start (If any). My ACs will not cycle on until after a 2 min delay of having power. Use your stop watch to time how long before they start after you you power has been supplied top the coach.

You should also have both ACs on to get the delta from when 1st AC start from the 2nd.

From what little we have, I am pretty sure you can stop the coach, turn on both ACs, fire up the Genset and go back to driving and you will save about 1 - 3 minutes depended on the rest of your test information. You will stay cool the rest of the drive

[marudnick]

Originally Posted by dkoldman

I have the Power Control System (hopefully you do too?) When I know it is going to be warm even with the DW, I will have both ACs on Auto On mode, normally the Genny is off when we are leaving. But as Coach warms up the HVAC will call the Genny to turn on.

We also have a Sunstar 29VE and have PCS. I’m intrigued with your comment about the A/C will call the Genny to turn on. How does that work?

[dkoldman]

Originally Posted by marudnick

We also have a Sunstar 29VE and have PCS. I’m intrigued with your comment about the A/C will call the Genny to turn on. How does that work?

We spent 2 years looking at all type of RVs. For us the Sunstar / Vista 29VE was by far the best for us. Although it was more expensive than all of the other units we compared it with, there was thing that it did NOT have that I absolutely had to have. That is the EC-30 Onan Cummins AGS. It comes standard with the Adventurer model but that coach was $20k more While the Adventurer was a clear upgrade the EC-30 was the only thing it had that we wanted. Since it basically was the same coach, I had the Winnebago install the EC-30 AGS in my coach exactly the way it is wired for Adventurer, but I took it a step further by having them connect the shore power sensor before the ATS. This was my very 1st Mod

The way it works.

When EC-30 is in Auto or Quiet Time modes, it monitors House & Chassis battery voltages as well any calls from our main front cabin area HVAC. So if the AC is set for 78 degrees and it is in auto modes, The thermostat will try to call the AC#1 to turn on if it hits 79 degrees, that same call goes to my AGS which in turns turn on genset on so the AC(s) can run. The Genset starts and runs 1 minute because before anything happens because the PCS is controlling the energy loads, once power is on; there is another 2 minute delay because of the Coleman ACs have built in delay.

So on a really hot day, with no shorepower, my genset does not have to run 24/7 to keep the coach cool We do the same thing when driving. Yes like most folks the front Chassis AC is generally enough, but when it is really hot it can be 85 degrees or higher in the back of coach, we set Acs for something like 81 or 82, just to keep it somewhat comfy and not too much pressure on chassis AC, if the kids are with us we may set it for 78 or 79.

[dkoldman]

Originally Posted by marudnick

We also have a Sunstar 29VE and have PCS. I’m intrigued with your comment about the A/C will call the Genny to turn on. How does that work?

Here is the EC-30.

https://www.youtube.com/watch?v=d9YlkK_R_Zo

It is actually my favorite Mod made to the RV It is like a toy that does so many useful things that most don't consider. On a lot of forums, some posts read like it is bad to run a genset, genset never works when they need them but they fail to say how long they have gone since properly exercising, anxiously ready to invest in Lithium regardless of practically of cost or the fact that you will need genset for ACs regardless of how $4k investment in Lithium

I did buy vMax tanks AGMs earlier this year before the prices started to increase.

https://www.youtube.com/watch?v=d9YlkK_R_Zo

[marudnick]

Originally Posted by dkoldman

We spent 2 years looking at all type of RVs. For us the Sunstar / Vista 29VE was by far the best for us.

We also spent some time looking for the right RV and selected the 29VE. This is our first and will likely be our last RV. (We’re retired.) We really do like it and have only minor quibbles. (I wish the driver’s dashboard was brighter. Sometimes it’s hard to see it, especially on bright days.)

Originally Posted by dkoldman

there was thing that it did NOT have that I absolutely had to have. That is the EC-30 Onan Cummins AGS. It comes standard with the Adventurer model but that coach was $20k more While the Adventurer was a clear upgrade the EC-30 was the only thing it had that we wanted. Since it basically was the same coach, I had the Winnebago install the EC-30 AGS in my coach exactly the way it is wired for Adventurer, but I took it a step further by having them connect the shore power sensor before the ATS. This was my very 1st Mod

Wow. I didn’t realize the possibilities. I’m sure it’s too late or expensive to add this to our rig. But it is nice to know about this feature.