Reply
 
Thread Tools Display Modes
 
Old 06-11-2012, 10:46 PM   #1
Bus Crazy
 
Diesel Dan's Avatar
 
Join Date: Feb 2009
Location: Austin, TX
Posts: 1,489
Year: 1996
Coachwork: Thomas
Chassis: International
Engine: DT466/AT545
Modified sine wave for a fridge?

Okay, I apologize in advance for stirring up trouble. This topic often gets people riled up - but I gotta ask: How many people have successfully run a refrigerator off a modified sine wave inverter for a reasonably long period of time (years). What I've gathered from previous discussions is that electronics are okay to run on MSW, but anything with a motor is better off with pure sine wave. Am I remembering that right? Anyways, I don't want to spend all that money on one of those pure sine wave inverters if I don't have to. I'm currently running lights, fans, and electronics on my 1500 watt modified sine wave inverter with no problems, but I'm getting ready to put in a fridge so wanted to see if anyone has any real-world experience with this to share.

Thanks!
Dan
__________________
Gallery:
https://www.skoolie.net/gallery/v/Skooli ... l_dan_bus/
Conversion Thread:
viewtopic.php?t=4959
Diesel Dan is offline   Reply With Quote
Old 06-12-2012, 12:40 AM   #2
Almost There
 
usmcbay's Avatar
 
Join Date: Mar 2012
Posts: 98
Year: 1995
Coachwork: Thomas MVP
Chassis: Saf-T-Liner ER
Engine: 5.9 Cummins
Rated Cap: 72
Re: Modified sine wave for a fridge?

I'm interested to see the replies....

No answers here tough...
__________________
Here's my Bus Conversion...

viewtopic.php?f=11&t=12202
usmcbay is offline   Reply With Quote
Old 06-12-2012, 04:44 AM   #3
Bus Crazy
 
Join Date: Mar 2011
Location: Oregon/Philippines
Posts: 1,660
Re: Modified sine wave for a fridge?

there was a pure sine wave on eBay a week or so ago that was used, but i had already spent more than i should have this month so i didnt bid on it...

all i have is a modified sign wave one, and have only run the micro and tv system on it, and that works fine, runs the smaller ac ok also.. but not at the same time.

i think eventually i will get a real spendy pure sine wave inverter, as well as something like a 8-12k diesel gen set, since that is the right way to have things in a conversion.
__________________
Jesus Christ... Conversion in progress.
chev49 is offline   Reply With Quote
Old 06-12-2012, 05:01 AM   #4
Bus Geek
 
bansil's Avatar
 
Join Date: Nov 2011
Location: MNT CITY TN
Posts: 5,158
Re: Modified sine wave for a fridge?

I am looking to do similar,except use a 5cu ft freezer converted to fridge.
I have read yes and no about invertors.
The fridge will use about 3 amps running(I am going withway highside and using 5amps fkor the math) so some say 8 to 10 times that to start the motor so 50 amp startup max.that would be a 6000watt surge needed.(problem is it works fine on a 15 amp 120 circuit so those number must be wrong)
Ithink that is way off tho' based on a 3000watt generator will easily power a fridge and small ac(unless they both kickon at the same time.
I am going to try it with a 1500 watt(3000) surge invertor,I have a couple laying around,it may work,may not
__________________
Our build La Tortuga
Accept the challenges so that you can feel the exhilaration of victory.
George S. Patton
bansil is offline   Reply With Quote
Old 06-12-2012, 08:19 AM   #5
Bus Crazy
 
somewhereinusa's Avatar
 
Join Date: Nov 2010
Location: Andrews,Indiana
Posts: 2,098
Year: 1991
Coachwork: Bluebird
Chassis: AARE
Engine: 3116 Cat 250hp
Rated Cap: Just the two of us.
Re: Modified sine wave for a fridge?

I ran a refrigerator on modified sine wave in my semi for years. Never had a problem. I'm also running the same setup in my camper. I can't tell any difference
running shore power or inverter. My latest inverters have a readout showing amps. I've never seen either one go above 80. Usually they do about 70 on start then drop off to
about 30. Your mileage may vary.
somewhereinusa is offline   Reply With Quote
Old 06-12-2012, 09:22 AM   #6
Bus Geek
 
bansil's Avatar
 
Join Date: Nov 2011
Location: MNT CITY TN
Posts: 5,158
Re: Modified sine wave for a fridge?

Good to hear that,lot's of people have said that they run small dorm and single door fridges off of 1500w inverters...but way to many cyber-neer's

What size fridge dorm type with what inverter size?just curious
__________________
Our build La Tortuga
Accept the challenges so that you can feel the exhilaration of victory.
George S. Patton
bansil is offline   Reply With Quote
Old 06-12-2012, 11:01 AM   #7
Bus Geek
 
lornaschinske's Avatar
 
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,587
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
Re: Modified sine wave for a fridge?

Quote:
Originally Posted by Diesel Dan
... What I've gathered from previous discussions is that electronics are okay to run on MSW, but anything with a motor is better off with pure sine wave...
It's the other way around... MSW for everything but electronics. SOME microwaves have problems with MSW. My theory is this... Plug it in and see. I know a lazer printer is Pure sine only but an ink jet is just fine on MSW. It's mostly "some" that don't like MSW on electronics.

MSW will power most anything. Start with MSW and if something objects, buy a little PSW unit. But I am a firm believer in using multiple inverters (that must be kept within 10 ft of battery bank) rather than one large one. I like to know that if one unit poops out, I can pull another unit into service temporarily. But mostly it's because I have one 750Watt(?) inverter now and may add another one later. One for lights and front TV. One in the rear for desktop computer, printer and rear TV. I don't really NEED the 2nd (rear) inverter but I would like one.

Figure to DOUBLE running watts for startup motor surge (minimum estimate... to be safe 2.5X and figure the fridge runs 24 hrs for load)
__________________
This post is my opinion. It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.
Fulltime since 2006
The goal of life is living in agreement with nature. Zeno (335BC-264BC)
https://lorndavi.wordpress.com/blog/
https://i570.photobucket.com/albums/s...ps0340a6ff.jpg
lornaschinske is offline   Reply With Quote
Old 06-12-2012, 11:24 AM   #8
Bus Geek
 
bansil's Avatar
 
Join Date: Nov 2011
Location: MNT CITY TN
Posts: 5,158
Re: Modified sine wave for a fridge?

Quote:
Originally Posted by lornaschinske

Figure to DOUBLE running watts for startup motor surge (minimum estimate... to be safe 2.5X and figure the fridge runs 24 hrs for load)
I figured in 30 AH for the fridge should be less in reality(if we don't consitently open and close it...also reason for using a freezer,cold air wont "roll" out)
__________________
Our build La Tortuga
Accept the challenges so that you can feel the exhilaration of victory.
George S. Patton
bansil is offline   Reply With Quote
Old 06-12-2012, 01:27 PM   #9
Bus Crazy
 
Diesel Dan's Avatar
 
Join Date: Feb 2009
Location: Austin, TX
Posts: 1,489
Year: 1996
Coachwork: Thomas
Chassis: International
Engine: DT466/AT545
Re: Modified sine wave for a fridge?

I will be getting a dorm fridge/freezer like this one: http://www.bestbuy.com/site/Haier+-+2.7 ... Id=1931487

There are no technical specs for Amp draw on this website, but I'm guessing it will only be like 1 or 2 running Amps. I have a 1200 watt MSW inverter, or maybe it's 1500 watts, I'll have to look. But either way, I think it will be fine even with the surge when the compressor kicks in. At most I'll be drawing 4 or 5 amps for a couple seconds.
__________________
Gallery:
https://www.skoolie.net/gallery/v/Skooli ... l_dan_bus/
Conversion Thread:
viewtopic.php?t=4959
Diesel Dan is offline   Reply With Quote
Old 06-12-2012, 01:54 PM   #10
Bus Geek
 
bansil's Avatar
 
Join Date: Nov 2011
Location: MNT CITY TN
Posts: 5,158
Re: Modified sine wave for a fridge?

those are the type of numbers I am expecting also
__________________
Our build La Tortuga
Accept the challenges so that you can feel the exhilaration of victory.
George S. Patton
bansil is offline   Reply With Quote
Old 06-12-2012, 02:25 PM   #11
Bus Crazy
 
somewhereinusa's Avatar
 
Join Date: Nov 2010
Location: Andrews,Indiana
Posts: 2,098
Year: 1991
Coachwork: Bluebird
Chassis: AARE
Engine: 3116 Cat 250hp
Rated Cap: Just the two of us.
Re: Modified sine wave for a fridge?

This is similar to both that I have, If you have the height I would recommend one with a separate freezer. In my opinion the freezer works much
better if it's a separate unit.Amps is what I said in previous post.

http://www.bestbuy.com/site/Frigidai...&skuId=9723536
somewhereinusa is offline   Reply With Quote
Old 06-12-2012, 03:02 PM   #12
Bus Crazy
 
Diesel Dan's Avatar
 
Join Date: Feb 2009
Location: Austin, TX
Posts: 1,489
Year: 1996
Coachwork: Thomas
Chassis: International
Engine: DT466/AT545
Re: Modified sine wave for a fridge?

Quote:
Originally Posted by somewhereinusa
If you have the height I would recommend one with a separate freezer. In my opinion the freezer works much
better if it's a separate unit.
I've been agonizing over that decision for some time now. The ones you describe are all about 3ft tall, and I need to squeeze whatever fridge I get into a 31" high space under my counter or face the prospect of tearing apart all my cabinetry in that part of the bus and rebuilding for the larger fridge. This was one area I did not plan out very well. I guess I was planning on using coolers but then changed my mind. Anyways, I think I'm going to just settle for the smaller fridge with built in freezer compartment for now and see how that goes.
__________________
Gallery:
https://www.skoolie.net/gallery/v/Skooli ... l_dan_bus/
Conversion Thread:
viewtopic.php?t=4959
Diesel Dan is offline   Reply With Quote
Old 06-12-2012, 03:20 PM   #13
Bus Geek
 
bansil's Avatar
 
Join Date: Nov 2011
Location: MNT CITY TN
Posts: 5,158
Re: Modified sine wave for a fridge?

this is what I am planning with a thermostate added,do you really need a freezer?
http://www.walmart.com/ip/Black-Deck...White/16681003

with something like this
http://www.amazon.com/Johnson-Contro...rds=thermostat

maybe mount it on slids?
__________________
Our build La Tortuga
Accept the challenges so that you can feel the exhilaration of victory.
George S. Patton
bansil is offline   Reply With Quote
Old 06-12-2012, 10:53 PM   #14
New Member
 
Join Date: Jun 2012
Posts: 3
Year: 1991
Coachwork: Ward
Chassis: Crane Carrier
Engine: 5.9 Cummins
Re: Modified sine wave for a fridge?

We had no luck burned up our 1st 18 cf "soft star" fridge so our current build we are going to use one of these as the fridge is the only AC device other than the 12v converter... New fridge is 16cf soft start....

It's a gamble but still cheaper then a Xantrex

http://www.ebay.com/itm/Ramsond-SunRay- ... 9772wt_722

Oh and I'm the annoying new Guy ;)

Eric
Serenity is offline   Reply With Quote
Old 06-12-2012, 11:19 PM   #15
Bus Crazy
 
Diesel Dan's Avatar
 
Join Date: Feb 2009
Location: Austin, TX
Posts: 1,489
Year: 1996
Coachwork: Thomas
Chassis: International
Engine: DT466/AT545
Re: Modified sine wave for a fridge?

Yeah the chest freezer hack is a great idea if your space allows and you don't need a freezer. I definitely need a freezer (I use ice packs for my sore old back!), and I need the door to open in the front since it will be under a cabinet.
__________________
Gallery:
https://www.skoolie.net/gallery/v/Skooli ... l_dan_bus/
Conversion Thread:
viewtopic.php?t=4959
Diesel Dan is offline   Reply With Quote
Old 06-13-2012, 12:53 AM   #16
Bus Nut
 
syke's Avatar
 
Join Date: Mar 2011
Location: from: Prescott, AZ currently: Denver, CO
Posts: 469
Year: 1992
Coachwork: BlueBird
Chassis: All American RE
Engine: 8.3 Cummins
Rated Cap: 72
Re: Modified sine wave for a fridge?

I've read in a few places that the motor will run a bit hotter with a MSW inverter. Therefore I'm planning to run a PSW with our chest fridge and freezer. Heat and motor longevity along with a small living space and I'll be needing all the coolness I can get.

We're running a similar setup to what you pictured Bansil. Been living with it in the sticks and bricks for about 8 months now. They are going with us into the bus.

Fridge runs 202 watts per 24 hours. 34 to 37 degrees F
Freezer runs 546 watts per 24 hours. Minus 1 to 4 degrees F
Running wattage starts around 140 and slowly drops to about 100 before the fridge or freezer shut off again.
Start up is hard to measure with my Kill-A-Watt as the unit shuts off during start up. I'm guessing over 2000 watts.
__________________
Ryan
Bluebird All American RE: Great White Buffalo (gone but not forgotten)
Our build thread: viewtopic.php?f=9&t=10065
syke is offline   Reply With Quote
Reply

Thread Tools
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
help with fridge vent lornaschinske Heating, Cooling and Appliances 5 06-11-2017 11:56 PM
Pure Sine VS Modified Wave Inverters TygerCub Conversion General Discussions 8 08-05-2012 10:06 PM
Smoothing out a modified sine wave AC signal icnivad Conversion General Discussions 2 02-06-2012 07:37 PM
Sine wave inverter alert Ob1 Conversion General Discussions 6 09-22-2010 09:15 PM
Propane Fridge ezbme Everything Else | General Skoolie Discussions 5 05-08-2009 10:17 AM

» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 11:42 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×