Reply
 
Thread Tools Search this Thread Display Modes
 
Old 03-18-2013, 08:42 AM   #1
2 Rivet Member
 
1977 28' Argosy 28
dexter , New York
Join Date: May 2012
Posts: 46
inverter to small motor run RV??

Iam new to posting i hope this is the right place . this idea my work great or just be another dum idea of mine . I have a 4000 watt onan gen set it eats 1 gal. / hr. my idea is to run 3500/7000 watt inverter connected to a small 4hp. motor electric start with a starter generator 15amp. delco it will run about 8 hrs. on a gal of gas . I may not have ac but lights frige tv charge battery .next a inverter is 12v to 110v and a converter is 110 to 12v ?some post seems to confuse these don't they or am Iwrong again ?so a 4hp. kohler delco starter generator 15amp 12-14 volt conected to a bat. bank to a inverter 3500 watt to the moho. any thoughts would be a big help thanks .
__________________

__________________
jonesy 1 is offline   Reply With Quote
Old 03-18-2013, 09:10 AM   #2
Rivet Master
Airstream Dealer
 
Inland RV Center, In's Avatar
 
Corona , California
Join Date: Feb 2002
Posts: 16,499
Images: 1
Quote:
Originally Posted by jonesy 1 View Post
Iam new to posting i hope this is the right place . this idea my work great or just be another dum idea of mine . I have a 4000 watt onan gen set it eats 1 gal. / hr. my idea is to run 3500/7000 watt inverter connected to a small 4hp. motor electric start with a starter generator 15amp. delco it will run about 8 hrs. on a gal of gas . I may not have ac but lights frige tv charge battery .next a inverter is 12v to 110v and a converter is 110 to 12v ?some post seems to confuse these don't they or am Iwrong again ?so a 4hp. kohler delco starter generator 15amp 12-14 volt conected to a bat. bank to a inverter 3500 watt to the moho. any thoughts would be a big help thanks .
W=EI

Wattage equals voltage times current.

3500 watts at 12 volts DC is almost 300 amps, at 100 percent efficiency.

WOW!!

Andy
__________________

__________________
Inland RV Center, In is offline   Reply With Quote
Old 03-18-2013, 09:15 AM   #3
Rivet Master
 
TG Twinkie's Avatar
 
1974 Argosy 26
Morrill , Nebraska
Join Date: Nov 2009
Posts: 5,139
Images: 2
Blog Entries: 5
You are correct in that a CONVERTER is 120 volt AC to 12 volt DC.
An INVERTER is 12 volt DC to 120 volt AC.
A 3500 watt generator will require a lot more than 4 HP to drive it.
I am not sure what you are trying to accomplish.
What is the electric motor for?
Where do you get the power to run the electric motor?
__________________
Knowledge: "A gift to be shared. A treasure to receive."
TG Twinkie is offline   Reply With Quote
Old 03-18-2013, 03:15 PM   #4
2 Rivet Member
 
1977 28' Argosy 28
dexter , New York
Join Date: May 2012
Posts: 46
sorry I of not expressed myself well . the 4hp. motor engine is gas with a starter /gen . it puts out 15amps. to charge a bank of 2or 3 bat. then a inverter 3500 watts constant 7000 quick start or cap. draw such as a electric motor starting ac. frige saw. would the 15 amp keep up with on off draw of the moho. ??thanks
__________________
jonesy 1 is offline   Reply With Quote
Old 03-18-2013, 05:24 PM   #5
Rivet Master
 
1988 32' Excella
Robbinsville , New Jersey
Join Date: May 2012
Posts: 1,008
Quote:
Originally Posted by jonesy 1 View Post
sorry I of not expressed myself well . the 4hp. motor engine is gas with a starter /gen . it puts out 15amps. to charge a bank of 2or 3 bat. then a inverter 3500 watts constant 7000 quick start or cap. draw such as a electric motor starting ac. frige saw. would the 15 amp keep up with on off draw of the moho. ??thanks
Short answer no.

15 amps@12 volts is 180 watts minus inefficiencies to an actual of about 150 watts or 1.25 amps@120 volts.

This would not be enough to run some 22" LCD TVs.
Another way to look at it is it could run a 1300 watt microwave for about 1 minute for every 2 hours the engine runs.

Now if you were talking about charging the batteries and almost exclusively using 12 volts it could work.
__________________
Wazbro is offline   Reply With Quote
Old 03-18-2013, 09:17 PM   #6
2 Rivet Member
 
1977 28' Argosy 28
dexter , New York
Join Date: May 2012
Posts: 46
I think I get it the starter gen. at 15 amp. output is not enough to keep up . the starter gen. is at the flywheel end of the motor I still have a shaft with nothing on it if it had a alt. say from a truck 100-125 amp. how do I figure how much power to turn it and would it keep up any better??
__________________
jonesy 1 is offline   Reply With Quote
Old 03-18-2013, 09:36 PM   #7
Rivet Master
 
Smartstream's Avatar

 
1982 28' Airstream 280
Port Angeles , Washington
Join Date: Aug 2008
Posts: 1,371
I think you are overlooking the fact that it takes one gallon per hour to run your Onan because it requires that much energy to make 4000 watts of electricity at 120 volts. If your small motor consumes 1/8 the fuel then it's output will also be about 1/8 as much. Also every time you change from gas motor to generator/alternator to inverter you lose more. We are not considering the cost of inverters and all the other items to make this work.

At the end of the day like lunch, nothing in energy is free.
__________________
Cheers, Dan
________________________________________


"Socialist governments traditionally do make a financial mess. They always run out of other people's money. It's quite a characteristic of them."
~ Margaret Thatcher ~
Smartstream is offline   Reply With Quote
Old 03-18-2013, 09:52 PM   #8
2 Rivet Member
 
1977 28' Argosy 28
dexter , New York
Join Date: May 2012
Posts: 46
ok I have a macullouf ?? they call it a flying magnet generator it puts out 5500 watts from a 10 hp. motor it uses 2gals.in 6 hrs . . and the thing is 110 and 220 v will run important things in my house in cold weather .I talked to a guy who said Iam not even loading it that it will put out a lot more because of its type . why so much differance to the onan at 12.5 hp 4000 watts this is what is hard to under stand .
__________________
jonesy 1 is offline   Reply With Quote
Old 03-18-2013, 09:52 PM   #9
Rivet Master
 
TouringDan's Avatar

 
1966 24' Tradewind
1995 34' Excella
Lynchburg , Virginia
Join Date: Sep 2009
Posts: 2,470
I am an engineer, but you have me real confused as to what you are trying to do.
Most Airstreams operate all they can using propane- fridge, water heater, stove and furnace. Battery storage, the heavier the more storage capacity, takes care of small electrical loads like lights (LED), TV, computer charging, cell phone charging, water pump, circulating fans, etc. I have two 6v golf cart batteries. I can easily go 4 days with careful use of my batteries and I have used only 25% of the battery capacity. I have a small 1,000 watt genny, but I don't even need to start it up to charge the batteries. It is really just an insurance policy, but I always bring it just in case I need it.

I suggest you look at just what your electrical loads are. Step one is always to minimize them- If my wife does not go with me, then I don't need the hair dryer and I have learned to live without the microwave and electric coffee pot. Once you identify and minimize the electrical loads then you can figure out how much battery capacity you need to meet your electrical requirements and figure out how to recharge your batteries.

Remember that new solutions have new problems. Don't try to reinvent the wheel if you don't have to.

Dan
__________________
TouringDan is offline   Reply With Quote
Old 03-18-2013, 10:12 PM   #10
2 Rivet Member
 
1977 28' Argosy 28
dexter , New York
Join Date: May 2012
Posts: 46
I guess you are right ,the largest draw is the PO idea to install a house frige. and stock ac , the onan that uses 1 gal. per hr. is the problem to me . the stock frige and no ac a 4hp. 12v gen. would be great .
__________________
jonesy 1 is offline   Reply With Quote
Old 03-19-2013, 07:36 AM   #11
Rivet Master
 
TouringDan's Avatar

 
1966 24' Tradewind
1995 34' Excella
Lynchburg , Virginia
Join Date: Sep 2009
Posts: 2,470
Why would you use a 12v genny? Who even makes one? I have a Honda 1000 watt genny that weighs 28 lbs and sips fuel, plus it is very quiet. I have yet to need it since I have not boondocked for more than 4 days. It will actually operate my 5k AC unit if we are camping in hot sticky weather.
When the genny is operating, all the 120v receptacles in the trailer are available and the batteries are charged up by the converter, just a hard wired sophisticated battery charger.

Dan
__________________
TouringDan is offline   Reply With Quote
Old 03-19-2013, 08:27 AM   #12
Rivet Master
 
1981 31' Excella II
New Market , Alabama
Join Date: Sep 2011
Posts: 5,648
Your generator has some problems. 1 gallon an hr is not good. I ran my whole house on a 5500W generator when the power was out for a week and I would use about 7 gallons a day.

Get you a small efficient gas generator like a Honda and use that to power the AC to DC converter in the trailer to keep your batteries charged. Going AC to DC is pretty efficient. Going from DC to AC is not very efficient. A big 5000 W generator running 1000W load is going to use more gas than a 2000 W generator with the same load. Honda make an EU2000 that can be ganged with another EU2000 to get 4000W total output to run the AC if you want. The higher the load on an engine the more gas it uses. So if you have an unloaded engine that runs 8 hrs, it may only run 1 hour at full load. 1000W should give you plenty to charge batteries with running 2-3 hrs a day. This is assuming you run everything else on propane.

Perry

Quote:
Originally Posted by jonesy 1 View Post
Iam new to posting i hope this is the right place . this idea my work great or just be another dum idea of mine . I have a 4000 watt onan gen set it eats 1 gal. / hr. my idea is to run 3500/7000 watt inverter connected to a small 4hp. motor electric start with a starter generator 15amp. delco it will run about 8 hrs. on a gal of gas . I may not have ac but lights frige tv charge battery .next a inverter is 12v to 110v and a converter is 110 to 12v ?some post seems to confuse these don't they or am Iwrong again ?so a 4hp. kohler delco starter generator 15amp 12-14 volt conected to a bat. bank to a inverter 3500 watt to the moho. any thoughts would be a big help thanks .
__________________
perryg114 is offline   Reply With Quote
Old 03-19-2013, 09:04 AM   #13
Rivet Master
 
1988 32' Excella
Robbinsville , New Jersey
Join Date: May 2012
Posts: 1,008
Quote:
Originally Posted by perryg114 View Post
Your generator has some problems. 1 gallon an hr is not good. I ran my whole house on a 5500W generator when the power was out for a week and I would use about 7 gallons a day.

Get you a small efficient gas generator like a Honda and use that to power the AC to DC converter in the trailer to keep your batteries charged. Going AC to DC is pretty efficient. Going from DC to AC is not very efficient. A big 5000 W generator running 1000W load is going to use more gas than a 2000 W generator with the same load. Honda make an EU2000 (1600 watt) that can be ganged with another EU2000 to get (4000W surge) 3200W total output to run the AC if you want. The higher the load on an engine the more gas it uses. So if you have an unloaded engine that runs 8 hrs, it may only run 1 hour at full load. 1000W should give you plenty to charge batteries with running 2-3 hrs a day. This is assuming you run everything else on propane.

Perry
Fixed that for you , the EU2000 is 2000 watts surge/1600 watts continuous. The marketing department is happy their misleading advertizing is working.
__________________
Wazbro is offline   Reply With Quote
Old 03-19-2013, 09:34 AM   #14
Rivet Master
 
1988 32' Excella
Robbinsville , New Jersey
Join Date: May 2012
Posts: 1,008
Quote:
Originally Posted by jonesy 1 View Post
I guess you are right ,the largest draw is the PO idea to install a house frige. and stock ac , the onan that uses 1 gal. per hr. is the problem to me . the stock frige and no ac a 4hp. 12v gen. would be great .
My parents had an Airstream with the stock propane fueled 12V generator, it was rather noisy and took quite a while to charge the battery (long time is mandatory due to the way batteries need to charge). They didn't use it enough to find out how much propane it used, just on one trip and running it once in a while to make sure it worked.

So before you try it start the engine and sit next to for a few hours to see how annoying the noise is to find out if it's worth dealing with. The inverter/generators from Honda and Yamaha are designed to be quieter then most other small engines.

Also their 1000s (900 watts) and 2000s (1600 watts) are nice and compact.
How much room is your homemade rig going to take?
Unless you are going to make it built-in, which adds vibration (which also transmits noise) into the annoyance.
__________________

__________________
Wazbro is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 08:12 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.