Can an ONAN put out 220v?

K

kab7

Active member
Sep 14, 2009
1,232
2
38
San Jose, CA
Hey all, we've been using our GMC Onan to power our house on the (increasingly frequent) occasions when
the power company turns off our power to supposedly prevent fires during windy dry conditions.
The Onan has been doing a great job of running the fridge, freezer, etc, but we can't run things
like a 220volt pressure system, water heater, or well pump with it.
I'm guessing that's because both hot legs of output are running in the same phase.

Does this make sense? Is there a way to output 220 volt power with our Onans, or is it 110 only?

thanks much,
Karen
1975 26'
 
Karen,

The original Onans in the GMC's are almost unique in that they are 110vac
ONLY! Even the cheapest Lowes/HomeDepot sold units today can run either
110 or 220 vac -- but NOT our Onans. Too bad. It is possible to use a
110:220 transformer. Determine the load you need to carry, in Watts and
Google "110:220 transformer wxyz Watts". For example "110:220 transformer
1000 Watts" yields these options:
https://www.amazon.com/ELC-T-1000-1000-Watt-Converter-Transformer/dp/B00FHIF8KC

But remember, your 6kW generator can probably only carry maybe 5kW through
a transformer.

Ken H.

On Sat, Oct 24, 2020 at 9:20 PM KB via Gmclist
wrote:

> Hey all, we've been using our GMC Onan to power our house on the
> (increasingly frequent) occasions when
> the power company turns off our power to supposedly prevent fires during
> windy dry conditions.
> The Onan has been doing a great job of running the fridge, freezer, etc,
> but we can't run things
> like a 220volt pressure system, water heater, or well pump with it.
> I'm guessing that's because both hot legs of output are running in the
> same phase.
>
> Does this make sense? Is there a way to output 220 volt power with our
> Onans, or is it 110 only?
>
> thanks much,
> Karen
> 1975 26'
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Costco has a sale on 9kw Firman generators right now. Don't remember the
price, offhand. It has 110/220. I bought one a couple of years ago. It is
Dual Fuel Propane/ Gasoline. Electric start. Has tires and folding handle.
Good unit.
Jim Hupy
Salem, Oregon

On Sat, Oct 24, 2020, 6:40 PM Ken Henderson via Gmclist <

> Karen,
>
> The original Onans in the GMC's are almost unique in that they are 110vac
> ONLY! Even the cheapest Lowes/HomeDepot sold units today can run either
> 110 or 220 vac -- but NOT our Onans. Too bad. It is possible to use a
> 110:220 transformer. Determine the load you need to carry, in Watts and
> Google "110:220 transformer wxyz Watts". For example "110:220 transformer
> 1000 Watts" yields these options:
>
> https://www.amazon.com/ELC-T-1000-1000-Watt-Converter-Transformer/dp/B00FHIF8KC
>
> But remember, your 6kW generator can probably only carry maybe 5kW through
> a transformer.
>
> Ken H.
>
>
> On Sat, Oct 24, 2020 at 9:20 PM KB via Gmclist

>
> > Hey all, we've been using our GMC Onan to power our house on the
> > (increasingly frequent) occasions when
> > the power company turns off our power to supposedly prevent fires during
> > windy dry conditions.
> > The Onan has been doing a great job of running the fridge, freezer, etc,
> > but we can't run things
> > like a 220volt pressure system, water heater, or well pump with it.
> > I'm guessing that's because both hot legs of output are running in the
> > same phase.
> >
> > Does this make sense? Is there a way to output 220 volt power with our
> > Onans, or is it 110 only?
> >
> > thanks much,
> > Karen
> > 1975 26'
> >
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
It is probably easier to get a 240/120 volt generator if you really need 240 volts. I have a 6 KW one here that I bought new over 40 years ago. It
has run everything 120/240 in the house (well, etc) except the AC. The few times I have used it over 40 years I never attempted running the AC.

We were without power here one winter for 6 days. I ran it in shared mode with my neighbor. 3 hours for me and 3 hours for them. I do not like the
neighbor that lives there now, so the last time we were without power I started the generator and turned on all of the outside lights after dark. I
never offered to share power with them. er were only down 6 or 8 hours.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
The Freight, Harbor uses the same engine, likely the same alternator, and it's a bit cheaper. I put one in the 23', worked fine. Note that these are
two - pole alternators (3600 RPM) so they will be a bit noisier than an Onan.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Karen,
In your situation you might just want to get a fixed, wired-in automatic generator.

Maybe contact a few electricians around you letting them know you would be interested in a second-hand unit if one comes up. They will have instances
of customers wanting to upgrade to more capacity and or features.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Look to the Freight, Harbor gensets which are relatively cheap and work well. An electric stove and an electric water heater, if both are on, are
going to load the genset greatly. My Onan holds up everything but the airconditioner/furnace, which runs on 220. If I anticipated a long outage I'd
pick up a transformer to run it, the load isn't great. However, the substation is a mile away and there are redundant feeds where I am, so even
downed lines require only the time it takes EMC to figure out which line to switch to.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
No, because the power comes from the rotor via slip rings and brushes. There are only 2 slip rings for the circuit. For 120/240V you need 3
connection points, 2 hots on separate phases and a neutral center point. The outer stator on ours just provides the magnetic field excitation and is
modulated by the compounding reactor to match load (somewhat).

--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Thanks everyone. We might look into other solutions in the future, but for now, this is good enough.
We can always shower in the coach if needed. I really like having our "GMC emergency-backup-house" :)

We're running right now on the Onan since PG&E has once again turned off our power. It started a bit rough
this morning, but is running like a trooper right now, though maybe an occasional miss. It's about the only
thing in the coach I haven't rebuilt or replaced, so I guess it might want a little attention. That'll be
a new learning experience, which the GMC has provided many of :)

Thank you,

Karen
1975 26'
 
Karen, if you have not already done so, replace your points type ignition
with a crank triggered upgrade like the one Gary Bovee markets. I did it to
mine, and it makes a good deal of difference in how it starts and runs. You
could go whole hog and convert it to dual fuel, but that isn't really
necessary. You will notice the difference with the ignition modification.
Easily within your skill set.
Jim Hupy
Salem, Oregon

On Mon, Oct 26, 2020, 11:41 AM KB via Gmclist
wrote:

> Thanks everyone. We might look into other solutions in the future, but
> for now, this is good enough.
> We can always shower in the coach if needed. I really like having our
> "GMC emergency-backup-house" :)
>
> We're running right now on the Onan since PG&E has once again turned off
> our power. It started a bit rough
> this morning, but is running like a trooper right now, though maybe an
> occasional miss. It's about the only
> thing in the coach I haven't rebuilt or replaced, so I guess it might want
> a little attention. That'll be
> a new learning experience, which the GMC has provided many of :)
>
> Thank you,
>
> Karen
> 1975 26'
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> Thanks everyone. We might look into other solutions in the future, but for now, this is good enough.
> We can always shower in the coach if needed. I really like having our "GMC emergency-backup-house" :)
>
> We're running right now on the Onan since PG&E has once again turned off our power. It started a bit rough this morning, but is running like a
> trooper right now, though maybe an occasional miss. It's about the only thing in the coach I haven't rebuilt or replaced, so I guess it might want
> a little attention. That'll be a new learning experience, which the GMC has provided many of :)
>
> Thank you,
>
> Karen
> 1975 26'

Karen,

Being an engine guy, I did not forget to shut down every so often (started at 8, went to 12 and finally at 18 hours) to check the lube oil level. It
turned out to be about a pint every 18 hours with a lot of load on it. Spark plugs need attention about 50~100 depending on how it is run.
Fortunately we started out with the coach fuel really go because we ran the Onan for a total of 76 hours.

The flywheel triggered spark is a very effective and worthwhile mod. It allows the engine to start better and run more smoothly.

The rated life to minor overhaul is like 2000 hours and the expected life of the unit (before a major overhaul is 8000 hours. (A week is 168 - I used
that a lot in dynoland and a year is 8760.) Do not ignore oil changes. I will suggest that you use a synthetic like Mobil 1. It is less subject to
many things that kill normal lube oils. If the old Onan starts to get real messy and leaky, take all the sheet metal and maybe the fly wheel
(carefully) and see what yo9u can tighten. I have nade more than a few into nearly no-leak this way.

This house has little 220 equipment (the A/C is about it), but we have used the Onan when the 40+yo standby Honda had a problem. Two houses back we
had a well pump, electric everything and little children. But I got a Honda that I could re-strap for 240. I still have that too. I will use it
when the coach is in the barn for the winter.

I might like to have 240, but when the lights are out A/C is just not a big issue. In the barn/shop, I can't use the compressor or the car lift.....

Matt
--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
 
Actually, when you consider it, you never need more than two slip rings on a generator. What generates EMF (electricity if you will) is the movement
of a magnetic field relative to a conductor. Instead of the volts per Hertx setup in small sets, an outboard regulator works quite well. One merely
spins the magnet and lets the conductor (winding's) be still. Since it takes substantially less current to produce a sufficient magnetic field than
the total current, the slip rings need only number two and need not carry the entire unit current. It also reduces rotating weight and makes three
phase alternators much simpler. Your car -or your GMC engine alternator actually uses a three phase AC alternator, and has a diode3 pack to rectify
the AC to DC. This is done with a single rotating field winding needing only two slip rings and uses a separate regulator to vary the field voltage as
necessary to produce the required output. Note that on the newer Onan RV sets, the exciter rotor (their terminology) spins and is energized through
the two slip rings. I was of the opinion our 5KW sets used the same system, but I may be wrong.

\]--johnny6

--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
> Actually, when you consider it, you never need more than two slip rings on a generator. What generates EMF (electricity if you will) is the
> movement of a magnetic field relative to a conductor. Instead of the volts per Hertx setup in small sets, an outboard regulator works quite well.
> One merely spins the magnet and lets the conductor (winding's) be still. Since it takes substantially less current to produce a sufficient magnetic
> field than the total current, the slip rings need only number two and need not carry the entire unit current. It also reduces rotating weight and
> makes three phase alternators much simpler. Your car -or your GMC engine alternator actually uses a three phase AC alternator, and has a diode3
> pack to rectify the AC to DC. This is done with a single rotating field winding needing only two slip rings and uses a separate regulator to vary
> the field voltage as necessary to produce the required output. Note that on the newer Onan RV sets, the exciter rotor (their terminology) spins and
> is energized through the two slip rings. I was of the opinion our 5KW sets used the same system, but I may be wrong.
>
> \]--johnny6

Johnny,

We got to listen to on of the Onan people that was part of the development team for the PowerDrawer. (He did allow that it was created for the GMCs.)

I asked why they did a stationary field and rotating armature and his response was that it was what they had on the shelf at the time. He die not
elaborate and I did not press the question farther. I still can't for the life of me think of any cost or manufacturing advantage for this
arrangement.

Matt
--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
 
My suspicion is they didn't want to spin an aluminum wound rotor... and had the fireld coils in aluminum abd available. But, just my suspicion.

--johnny

--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
> Does this make sense? Is there a way to output 220 volt power with our Onans, or is it 110 only?

THis question has been well-answered but if you had your heart set on 240VAC from your GMC I am pretty sure an Onan Emerald will fit in the space and
many of them are 6.5 with 240 as an option.

I am currently putting a 4.0 emerald into a Birchhaven. I will relocate one of the power-drawer slides and it should fit pretty well.

--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
Check the engine on the Emerald. Some newer small sets are using an engine made offshore. Same or similar to Predator, Champion, others. The point
being, to me anyway, is I'll give a bit of a premium for an Onan designed and built engine. If it uses the hashimoto mouse engine I'm liable to shop
price and dealer rep. Kanomata's reputation is worth a premium as well. Pay your money but in such a competitive field look very closely.

--johnny

--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
You must log in or register to reply here.
GMCMI Fall 2026 Rally
Applied GMC

Share this page

Share this page
Top Bottom
Back