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Old 01-13-2023, 02:33 AM   #1
Mini-Skoolie
 
Join Date: Jan 2021
Location: Atlanta, GA
Posts: 12
Year: 2004
Coachwork: Blue Bird
Engine: 8.3L Cummins
Rated Cap: 36,000lbs
Generator Size?

I'm once again knee-deep in a rabbit hole. I'm trying to choose a generator, as a backup, & I just can't decide.

I chose a dual-zone Sennville mini split(9k bedroom/9k front), a residential fridge, & all the other usual amenities for my Skoolie. After researching with other Skoolie owners, I've chosen to go with 50A instead of 30A(I think). I refuse to be too hot/cold, & I don't want to be in the dark if I experience a lot of cloudy days. Oh yeah...I'm going with around 2600w solar, with 4-200AH SOK batteries(Victron everything else)

Here's my question: What's a reliable generator you guys would recommend, that will power one of my mini split zones/fridge/a tv... if necessary?

I appreciate feedback. I second guess every step of my build, I over-engineer, I'm trying to build my rig to be prepared for power/Security contingencies, but I don't want to break the bank.

Oh...I've got 26˝" height room available for the generator. I fabricated a cage for the future gen/mini split right behind the 2 front wheels...

RECOMMEND AWAY & THANKS!
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Old 01-13-2023, 03:33 AM   #2
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Join Date: Sep 2019
Location: Bly Oregon
Posts: 466
Year: 1986
Coachwork: Crown
Chassis: Supercoach
Engine: Cummins 350 big cam
Rated Cap: 86 passengers?
To determine what capacity of generator you select for your project, first determine what your electrical load will be. Once you determine your load, add 20 - 30% to that and get the generator at that capacity. Also consider what fuel you want to run the generator on. Diesel, gasoline, and propane are the possible choices. The physical dimensions are also key to the decision. The budget you have available comes into play as well. Brand name of good generator? Onan, Generac, Kolher are excellent makes to consider. I have had good results with Onan both gas and diesel. The gas powered Onans are not as tall as the diesel version. When considering The gas powered Onans evaluate the distance from the exhaust pipes to your floor, as the ones I have place the exhaust at the top of the generator. The diesel Onan I have in the bus has exhaust on the side. If you choose a generator that uses a different fuel than your bus then you need a fuel/gas tank for the generator. Even if your generator uses the same fuel type as the bus, you probably still want a separate tank. Consider where to put that tank, and how to fill it.


Your generator installation should allow for easy access to change the oil in your generator.


Popular RV generator sizes are 4, 5, 6.5, 7.5 Kw for Onans made for RVs. I believe that Generac also makes generators of similar size. Your generator should be as far away as possible from where you sleep to minimize the noise and risk from exhaust gases. Install a carbon monoxide detector as well.


When we lived in the Santa Cruz mountains before we retired we kept an old Kohler generator hardwired to the house and had to use it every winter due to multiple power outages each year. I had to repair the generator when I bought it used, but never after that for a period of 30 ? years. It went with the house when we sold it.
Military generators are very well made but they are large and heavy for their capacity.


Did mention considering used or new? Both of my Crowns got used generators, with considerable savings in cost. Both are RV generators of 6.5 Kw capacity. The "old Crown" has a two cylinder opposed gas engine, and the "new Crown" has a diesel 3 cylinder in-line engine. I like the diesel more, and the gas one fit easier.


One last thought: consider the weight of the generator. Are your mounts able to carry the weight of the generator you picked. When you are going down the road and hit a big pothole the g forces resulting could be 2 Gs (or maybe more). That means the 500 lbs generator exerts a force of 1000 lbs for a fraction of a second (at 2 Gs) Once you have the answers for all of thses considerations you will have the means to pick the right generator.
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Old 01-13-2023, 09:05 AM   #3
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Location: Alabama
Posts: 154
Year: 1996
Coachwork: BlueBird
Chassis: International 3800
Engine: DT 466 Mech. Spicer 5 speed
Rated Cap: 34
Quiet generator

Cheap generators tend to be noisy, which is important to me. If I am going to have to listen to that thing all day or night, I want it to be as quiet as possible. Another consideration is the operating rpm of the generator. On older units, many were 1800 RPM which is a lot more pleasant than a 3600 RPM unit. On an invertor style generator, if it is sized large enough, it can run at lower RPM most of the time, which makes those more pleasant to be around.
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Old 01-13-2023, 10:24 AM   #4
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Join Date: Oct 2021
Location: Jax Beach, FL
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Year: 2003
Coachwork: BlueBird
Chassis: TC2000 28ft
Engine: Cummins ISB 5.9 24v, MD3060
Rated Cap: 14
That Senville dual zone unit is probably 220v split phase. I have never seen a dual zone mini-split that runs on 120v. That limits you to a split phase generator. Also, you have to factor in what inverter you are running and how that is hooked up. For instance, i am doing an All-In-One inverter with a dedicated generator hookup. When my batteries get low, the signal will output to trigger the generator controller. I preset the amps that it can charge for generator plug, so i don't exceed capacity of the generator. So in this way, if my batteries are undersized, and they only last 3 hours with my mini-split running at night, the generator can turn on and run for 1 hour to recharge the bank and then rest for 3 hours. These inverters set their specification for power requirement. Mine has a THD below 5% which cheaper generators don't do.



I have a Champion 7000w Gas Inverter open-frame Generator (split-phase). I had this before my bus for backup power in hurricanes. They make these down to about 5000w. Its not too bad at idle, but when it gets any load above 2000w, its awfully loud and it cant be enclosed because its air cooled. It could be put in an compartment with fan cooling and exhaust outlet, but its not going to pass the national park decibel limit and people are going to be annoyed.


I didn't want to deal with bringing a different fuel source with me on the road, so i was set on diesel. I'm on a budget, so 10k for a new diesel generator were out the question. I was searching for auction Onan RV generators. The smaller ones aren't 1800rpm limited because they have smaller engines (like a 500cc 2 cylinder kubota) and they have to get to a high RPM to get enough horsepower for their full 5000w output. Also, the parts on onan RV generators are fairly proprietary. You'll find many stories about a bad part (like or rotor or stator) costing 2-3k and causing the generator to be thrown away. Also, onan uses brushed genheads which means one more thing to service.



My ideal unit would be a Powertech 12kw quiet diesel generator. I got a quote on one and it was 18k. I actually bid on one on ebay and would've won, but the seller said they ran over it with a forklift before the auction ended and had to try to repair it. (or it was going too cheap for them).


I also have a height constraint. I want my total height to be less than 24in so i don't lower my clearance or have a goofy looking skirt.



So what i decided on was to copy the powertech design with parts from a diesel light tower. This was $600 from auction and i will spend another $400 on parts for a remote radiator and exhaust routing. Light towers are very serviceable. Most come with a marathon electric brushless generator heads. These are okay(im going to try mine before upgrading), but they can be swapped with an entire new AVR genhead for around $1000. They run a Kubota diesel which i still see running into the 30k to 60k hours.


The best part is that at full load, they use 1/2 a gallon per hour. At idle, they use like 1/10th of a gallon. In the end, the thing will be absolutely silent, serviceable, and compact.


If you don't want to spend time building one, i highly recommend an 1800rpm diesel generator.



If you have a bigger budget than me and just want to buy one, the place below is highly regarded in the generator industry, and they are just down the road from you.


https://centralgagenerator.com/


I, like you have spent too much time overthinking things, so I'm hoping all my generator research is not for nothing.
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Old 01-13-2023, 12:43 PM   #5
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Location: Rapid City, SD
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You will want to size your generator so that it can handle the load from the appliances you want to run plus what is needed to charge your battery bank.

Ted
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Old 01-13-2023, 03:29 PM   #6
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Join Date: Sep 2019
Location: Bly Oregon
Posts: 466
Year: 1986
Coachwork: Crown
Chassis: Supercoach
Engine: Cummins 350 big cam
Rated Cap: 86 passengers?
Another bit of info on choosing your generator:
The older Onans that I am familiar with can be configured for 240VAC or 120 VAC. the older 2 cylinder Onans are configured with 4 wires in the electrical box where the output from the generator comes from. The cover for that electrical box has the wiring diagram inside of it. The diesel Onan I have was more complicated, requiring opening up the control box and changing the connections inside. The various manuals for that series are on-line. I spent a couple days figuring out what and how to change the connections. I documented what the final configuration was. Onan also labeled the wires inside of the control box. I believe that I posted about the generator re-configuration in my thread "The conversion of my 86 Crown Supercoach".


One can find parts for the Onans but they are spendy to get.



One solution for exhaust noise from a generator is using a stock Harley Davidson muffler. A lot of Harley riders like to hear their exhaust note and replace the stock exhaust system (or at least the mufflers) so stock mufflers are easy to get and not expensive. Get the ones for a big twin.
If you make your own exhaust system assure that the end of the exhaust is outside your bus, not underneath. For guidance go to an RV dealer and look at how it done on a factory made RV. Most of the ones I have seen have the generator up front and the end of the exhaust pipe sticks out from underneath the side.
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Old 01-15-2023, 08:24 PM   #7
Mini-Skoolie
 
Join Date: Jan 2021
Location: Atlanta, GA
Posts: 12
Year: 2004
Coachwork: Blue Bird
Engine: 8.3L Cummins
Rated Cap: 36,000lbs
A Harley muffler? Great idea! I bet it sounds mean! LOL!
Thanks!
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Old 01-15-2023, 09:28 PM   #8
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https://generators.visonerv.com/cgi-bin/welcome.pl?

Looks like the only game on the internets for used RV generators.... any other leads?
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Old 01-15-2023, 11:42 PM   #9
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Location: Jax Beach, FL
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Engine: Cummins ISB 5.9 24v, MD3060
Rated Cap: 14
Quote:
Originally Posted by La Camioneta View Post
https://generators.visonerv.com/cgi-bin/welcome.pl?

Looks like the only game on the internets for used RV generators.... any other leads?

Yeah i kind of gave up looking for used. They are out there, but not super widespread. I think most from the used market are from wrecked or RV part outs. Facebook marketplace had the best supply i saw. There's a group you can check for more, but better to keyword search near your location though. I think most RV people (with diesel gensets), have the one that comes with the RV and probably sell it with the RV.



https://www.facebook.com/groups/2017515525167306/
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Old 01-18-2023, 06:16 PM   #10
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I will be selling my Onan 6.0 DJB diesel generator soon if you or anyone else is interested. It's a 120/240 split phase that runs at 1800 RPM. It's very heavy duty, but a bit noisy. I have all the PDF manuals for it, too. It's in really great condition with fresh oil, oil filter, fuel filters, and air filter. Starts quickly and runs well. No leaks or any other known issues. I added an hour meter to it, too. Probably need $1500 shipped via air cargo to a major airport, or $1400 picked up locally just outside of Austin, Texas.
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Old 01-19-2023, 02:06 PM   #11
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Year: 1998
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Chassis: Amtrans
Engine: 444E
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Quote:
Originally Posted by BigTiny321 View Post
I'm once again knee-deep in a rabbit hole. I'm trying to choose a generator, as a backup, & I just can't decide.

I chose a dual-zone Sennville mini split(9k bedroom/9k front), a residential fridge, & all the other usual amenities for my Skoolie. After researching with other Skoolie owners, I've chosen to go with 50A instead of 30A(I think). I refuse to be too hot/cold, & I don't want to be in the dark if I experience a lot of cloudy days. Oh yeah...I'm going with around 2600w solar, with 4-200AH SOK batteries(Victron everything else)

Here's my question: What's a reliable generator you guys would recommend, that will power one of my mini split zones/fridge/a tv... if necessary?

I appreciate feedback. I second guess every step of my build, I over-engineer, I'm trying to build my rig to be prepared for power/Security contingencies, but I don't want to break the bank.

Oh...I've got 26˝" height room available for the generator. I fabricated a cage for the future gen/mini split right behind the 2 front wheels...

RECOMMEND AWAY & THANKS!
Just a note. I'm having trouble with skoolie.net telling me I'm not logged in and wiping out my answers, so this answer that I am posting is the result of me wisening up and copying my text before I hit the submit reply button. It is also considerably truncated because this is my third try. Feel free to ask questions if you would like me to expand on any of the things but I have shared.
Quote:
Originally Posted by BigTiny321 View Post
I'm once again knee-deep in a rabbit hole. I'm trying to choose a generator, as a backup, & I just can't decide.

I chose a dual-zone Sennville mini split(9k bedroom/9k front), a residential fridge, & all the other usual amenities for my Skoolie. After researching with other Skoolie owners, I've chosen to go with 50A instead of 30A(I think). I refuse to be too hot/cold, & I don't want to be in the dark if I experience a lot of cloudy days. Oh yeah...I'm going with around 2600w solar, with 4-200AH SOK batteries(Victron everything else)

Here's my question: What's a reliable generator you guys would recommend, that will power one of my mini split zones/fridge/a tv... if necessary?

I appreciate feedback. I second guess every step of my build, I over-engineer, I'm trying to build my rig to be prepared for power/Security contingencies, but I don't want to break the bank.

Oh...I've got 26˝" height room available for the generator. I fabricated a cage for the future gen/mini split right behind the 2 front wheels...

RECOMMEND AWAY & THANKS!
Ruth and I live in our bus full time in the desert of southern New Mexico. We prefer to live in our bus as if we are connected to the grid.
With that being said, unless you are only going to use your bus on full Sundays in the southern part of the United States or Mexico or South America, you don't have enough solar panels, or enough battery in order to live the way you have described in your post.
When Ruth and I first started living in our bus, we had no solar. We had a 3500 Watt champion generator that we ran 9 to 12 hours a day. That was back when gasoline was less than $2 a gallon and it was running us about $600 a month.
We got really tired of watching our money float off into the atmosphere. So, we pulled our belts tight we saved our money and we started buying the components that we thought we needed to become generator free.
The number of panels that we had and the number of batteries continued to grow over the next year or so as we found the size that allowed us to live in relative comfort.
We now have 12 327 w solar panels and six 24 volt byd 200 amp hour batteries.
This allows us to live almost as if we are connected to the grid. It really only gives us about 8 hours reserve. Meaning, if it is cloudy and hot or cold, after 2 days or more we may have to heat with propane, or stay cool by taking some clothes off.
Since you didn't say whether you are operating a 12 volt system, 24 volt system, 48 volt system, I am going to base this next part of my answer on a 24 volt system. If you have four 24 volt 200 amp hour batteries multiply the 200 amp hours by 4 and that by 24 that gets you your kilowatt hours.
19,200Kwh sounds like a lot, but that is from 100% state of charge to 100% discharged. Your solar controller, and your inverter won't really let you do that. Your $2,600 watts of solar panels probably won't let you do that either.
If you start out with your batteries completely drained from the night before it's going to take everything that your solar panels can give you to get those batteries topped back off before the sun is too low in the sky to provide you much energy.
Realistically, if indeed we are talking about 24 volt batteries, four of them at 200 amp hours, you can probably run your mini split for about 9 hours before you are at about 20% state of charge. From 20% state of charge back to the 100% state of charge in full sun in New Mexico will probably take until about 3:00 or 4:00 p.m.
Our recommendation, before you start looking at your generator is to consider at least 4 kilowatts of solar panels, and a thousand amp hours of batteries at 24 volts.
This will give you in most situations the freedom to live comfortably without having to run the generator.

As for a generator to run the loads that you have mentioned, a 5 KW generator running at 50% will handle those loads just fine. Why 50%? Because it is easier on the generator and it will last a lot longer. Also it consumes less fuel.
The next concern with a generator mounted to your bus is how much noise does it make. An inexpensive champion or predator generator will do the job but they are noisy. I guarantee you you'll get tired of the noise. You can get a champion or predator 5 kilowatt generator for 5 or $600.
A much quieter Honda generator can run between two and three thousand dollars.
I think if I were in your situation I would go with the lesser expensive generator and size my solar system to never have to use it.
We still have the 3500 watt champion, in 2022 the number of days it ran was zero. We like that.
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Old 01-24-2023, 05:49 AM   #12
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Location: Southern Oregon
Posts: 1,334
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Coachwork: AmTran (Now Navistar)
Engine: DT444E (7.3L) International
Rated Cap: 31,800 pounds
We're building out with 2900W solar, 6.5kW inverter (13kW surge), and two 24 volt EG4 batteries (10.24kWh). We chose to go with TWO minis. A 12k BTU in the front over the windshield and a 9k BTU in the rear bedroom. The minis take 800W and 1000W respectively but ONLY when the compressor is running so we figure the average will be substantially lower due to insulation, roof covering with air gap, window removals, door sealing, etc. This will be particularly true at night as the main compartment can be turned down, a door or curtain to close off the bedroom, and the 9k mini which is sized for 400SqFt room in a house with at least an 8 foot ceiling (i.e. we have less cubic feet) should just putt along all night long while sipping pixies.
We have chosen to go with a Predator (Harbor Freight) 3500W inverter generator because we've had excellent service out of the one we have. When we have to replace it, we will be looking for one with a remote start capability but that's the only drawback to the Predator 3500 and it's quiet.
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Old 01-29-2023, 02:05 PM   #13
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Join Date: Jan 2023
Location: New Orleans, LA
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Quote:
Originally Posted by ChrisTX View Post
I will be selling my Onan 6.0 DJB diesel generator soon if you or anyone else is interested. It's a 120/240 split phase that runs at 1800 RPM. It's very heavy duty, but a bit noisy. I have all the PDF manuals for it, too. It's in really great condition with fresh oil, oil filter, fuel filters, and air filter. Starts quickly and runs well. No leaks or any other known issues. I added an hour meter to it, too. Probably need $1500 shipped via air cargo to a major airport, or $1400 picked up locally just outside of Austin, Texas.
Chris I would like to talk to you about your genset. Please email me Vince @ Lhhco com……Thanks!
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Old 01-29-2023, 02:07 PM   #14
Mini-Skoolie
 
Join Date: Jan 2023
Location: New Orleans, LA
Posts: 11
Quote:
Originally Posted by ChrisTX View Post
I will be selling my Onan 6.0 DJB diesel generator soon if you or anyone else is interested. It's a 120/240 split phase that runs at 1800 RPM. It's very heavy duty, but a bit noisy. I have all the PDF manuals for it, too. It's in really great condition with fresh oil, oil filter, fuel filters, and air filter. Starts quickly and runs well. No leaks or any other known issues. I added an hour meter to it, too. Probably need $1500 shipped via air cargo to a major airport, or $1400 picked up locally just outside of Austin, Texas.
Chris I would like to talk to you about your genset. Please email me Vince @ Lhhco com……Thanks!
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