Thread Tools Search this Thread Display Modes
Old 11-23-2006, 11:30 PM   #1
4 Rivet Member
walter1's Avatar
1964 22' Safari
Foresthill , California
Join Date: Aug 2004
Posts: 257
Inverter transfer switch help

I am installing an inverter to power the AC system when boondocking (will only be used very short periods so as not to kill battery).

I want to install a manual transfer switch. Simple, eh?

Where can I obtain a 30A transfer switch that isn’t bulky and doesn’t cost more than the inverter did?

This switch would have main shore power wiring to one pole, inverter power to other pole, feeding out to main AC circuit breaker panel.

A heavy duty 30Amp, double pole/ double throw switch should do it.

All I can find are marine grade, generator type, AC selector switches that sell for $140 (West Marine part # 5426630, BLUE SEA SYSTEMS, Mfg # 9009).

Anything sold as MARINE seems to be $$$$$$.

Can I use an automatic transfer relay out of an AS motor home?
How do these determine which line is hot? Are they reliable? What happens if someone switches inverter on while shore power is still connected?


walter1 is offline   Reply With Quote
Old 11-24-2006, 12:59 AM   #2
Site Team
azflycaster's Avatar
1975 25' Tradewind
Dewey , Arizona
Join Date: Mar 2005
Posts: 12,037
Images: 62
Blog Entries: 1
The issue of running big inverters comes up once in a while on the forum and I wonder if anyone has done what you are looking at doing. The reason I ask is the amount of power requires to generate that much current. I found this chart which shows the battery life based upon the amount of current created. Unless you are going to carry a bunch of batteries, I don't see how this could be pratical.
Attached Thumbnails
Click image for larger version

Name:	inverterchart.jpg
Views:	124
Size:	55.0 KB
ID:	28961  



WBCCI President 2016-2017
azflycaster is offline   Reply With Quote
Old 11-24-2006, 01:15 AM   #3
4 Rivet Member
walter1's Avatar
1964 22' Safari
Foresthill , California
Join Date: Aug 2004
Posts: 257
I was wondering the same. Has anyone tried wiring in and using a big (ie. 1750w) inverter)?

Thanks, the chart is helpful.

I got the inverter cheap. I know electrically you can't get more out than goes in, V=IR and all. Don't want to toast the battery.

I just like toast.

Thanks, Walter
walter1 is offline   Reply With Quote
Old 11-24-2006, 05:52 AM   #4
Moderator Emeritus
Pick's Avatar
1972 31' Sovereign
High Springs , Florida
Join Date: May 2002
Posts: 2,310
Images: 36
Send a message via AIM to Pick
They do make DPDT 220V wall switches. They are kind of hard to find. Try an electrical supply company. I doubt HD or L will have them, but you can look. They may not handle 30 amps though. I had one on a 220v well pump, so I know they exist.
2003 GMC 2500HD 4X4 D/A Ext. Cab
Propane Powered Honda EU2000i
Lots of Hot Sauce!
Air # 283
WBCCI 1350
Pick is offline   Reply With Quote
Old 11-24-2006, 06:10 AM   #5
4 Rivet Member
steelbird312's Avatar
1956 22' Safari
2000 39' Land Yacht XL Diesel w/slide
Crossville , Tennessee
Join Date: Sep 2003
Posts: 413
Images: 11
cost prohibitive

That inverter will cost you much more in other costs than what a Yamaha or Honda quiet generator would...and the generators have multiple use scenarios, while the inverter would definitely be a dedicated item along with $2000 worth of batteries!
2000 390 Landyacht XL
1989 29' Excella
WBCCI #6673 jerry Hodge
Have no intention of arriving at the grave safely, but rather to skid in sideways, chocolate in one hand,throttle in the other, totally worn out and screaming
steelbird312 is offline   Reply With Quote
Old 11-24-2006, 10:07 AM   #6
More than one rivet loose
thecatsandi's Avatar

Currently Looking...
Keymar , Maryland
Join Date: Feb 2006
Posts: 3,753
My onboard inverter powers two outlets in the trailer. One by the writing desk and the other by the TV. No Transfer switch. THere is a transfer switch for the generator hookup though.
Michelle TAC MT-0
Sarah, Snowball

Looking for a 1962 Flying Cloud

thecatsandi is offline   Reply With Quote
Old 11-24-2006, 10:41 AM   #7
Rivet Master<br><img src="/ugala/forums/images/5rivet.gif">
CanoeStream's Avatar

2006 25' Safari FB SE
St. Cloud , Minnesota
Join Date: Aug 2003
Posts: 13,279
Images: 19
Blog Entries: 3
Has this ever been done?

So switches are available. You ask about use for short periods -- and it is certain that is all you'd be able to do. And then what? You'll not want to use more than 60% of your battery capacity or else you'll diminish their service life significantly. And then you'll not be able to use anything electrical until you replenish your batteries. This sounds like a clear case for a portable generator and not going thru the middleman (ie, batteries).

[on edit: Adding more batteries to make this even occasionally practical will severely push the dynamics of trailer loading, hitch weight, GVWR, etc.]

Recharging batteries with anything short of a home or campground electric hookup or 110v generator will be slow. Two rather slow options are thought of commonly -- solar and your tow vehicle's alternator. The latter supply line is thin, long, and can take 2-300 miles of driving before your batteries are topped off for instance. Using the umbilical and tow vehicle batteries in this way risks having your tow vehicle "wake up dead."

The more common quiet Honda eu2000i doesn't put out quite enough amps to start up the AC. The compressor requires about 20-22 amps at startup IIRC (less when up and running). Many threads out there in Forums on this topic ... Solar battery recharge (not running the AC!) is a very expensive option for what you get -- slow, occasional, and maybe not ready when you are.


5 meter Langford Nahanni

CanoeStream is offline   Reply With Quote

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
New battery selector switch FrankR Electrical - Systems, Generators, Batteries & Solar 6 02-08-2013 06:34 PM
Inverter problem Don McKelvay Electrical - Systems, Generators, Batteries & Solar 2 11-03-2002 05:40 AM
igniton switch and the mystery of the dead battery Curtis-79MH Airstream Motorhome Forums 3 10-25-2002 02:58 PM
Rotary Light Switch 74SovereignInt. Electrical - Systems, Generators, Batteries & Solar 20 10-15-2002 06:31 PM
What the heck is that switch on the wall??? TRAPEZE Airstream Motorhome Forums 7 09-10-2002 04:05 AM

Virginia Campgrounds

Reviews provided by

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 05:51 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.

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