Inverters

ChiefJohn · 01-31-2013, 06:49 AM

Okay folks, preface it to say that I'm ignorant when it comes to inverters, appreciate the feedback/assistance -- we have the 2000w modified (quasi) sine wave inverter installed by Winnebago. I'm hesitant to use this inverter to power our computer, printer, TV, and soon to be installed residential refrigerator due to the possibility of damaging the electronic components. Do we need to replace this modified inverter with a pure sine wave?

Jim Estes · 01-31-2013, 07:08 AM

Check the owners manual for your inverter...it may cover your question. Also I notice that most new Class A's with residential fridges come with a 3000 watt inverter...

bruceisla · 01-31-2013, 07:19 AM

One of the things to think about is:

Do you really "need" to power the new reefer from an inverter? Shore power and the genset provide ample pure sine wave power and most new reefers can go many hours without power without the temp rising more than a few degrees.

RedWing Nut · 01-31-2013, 08:25 AM

We had the same setup in our last MH and the only problem we had was with electric blanket controls. It fried them right away. LED TV, satellite receiver, DVD player, PCs and residential fridge all worked great.

If I was to put an inverter in our present MH it would be pure sine, for sure.

motohomer · 01-31-2013, 08:50 AM

You may also need to add more batteries.

Since you are going through all the trouble & expense of a new fridge, you may want to consider upgrading the inverter and batteries now, & be done with it.

Z714X4 · 01-31-2013, 09:01 AM

Quote:

Originally Posted by ChiefJohn

Do we need to replace this modified inverter with a pure sine wave?

NEED to, I don't think so... but you may want to. Reading these forums I see lots and lots of people use an MSW inverter and have no problems at all with any of their equipment.

As for me, when it came time to purchase mine, I just figured why be concerned at all... I don't need something else to think about so I started with the pure sine and now never give it another thought. It's no longer a factor, concern, or even a thought for me.

I have read that some refers do not like MSW, but maybe you could contact the mfg and see if they have any specs or info for that.

John Hilley · 01-31-2013, 09:05 AM

While not the quality of a pure sine wave inverter, I wouldn't worry about using your inverter for your listed devices. i would post a question about whether or not anyone has used that inverter with the frige you have chosen.

halfwright · 01-31-2013, 09:12 AM

My understanding is that a modified sine wave shortens the life of anything it does not fry immedeatly. Pure sine wave inverters are much more expensive, but we went with a 2000 watt pure sine wave inverter, 4 150 solar panels, 4 6 volt 225 amp hour batteries and a MPPT charger. We can boondock indefinetly as far as electricity goes, but still need water and a dump site every 10 days to two weeks.

Five2o · 01-31-2013, 09:21 AM

I've full timed going on 3 years with a 2000w modified (quasi) sine wave inverter powering everything from charging computers/phones/ipod to powering our 3 way fridge,home theater etc etc without incident.

ChiefJohn · 01-31-2013, 10:09 AM

Quote:

Originally Posted by Jim Estes

Check the owners manual for your inverter...it may cover your question. Also I notice that most new Class A's with residential fridges come with a 3000 watt inverter...

I'm well aware of what the owners manual states and does not address -- my question is for those with an electronic background/knowledge to help me understand the "potential damage" a modified-sine inverter may do to computers, printers, etc. -- some folks appear to have no problems with this type of inverter. We're installing a Whirlpool residential refrigerator next week and our intent is to use the inverter while on the road. The generator is an option and we have used it in the past, with the cost of fuel, the inverter appears to be the more economical.

John Hilley · 01-31-2013, 10:30 AM

Todays electronics for the most part use switching power supplies which work fine with MSW inverters. The devices with transformer power supplies can have problems as do devices that rely on the 60 cycle wave form for timing, such as clocks. If the fridge works fine you shouldn't have any thing to worry about.

smlranger · 01-31-2013, 06:50 PM

I would suggest you check with the manufacturer of the residential fridge you plan to use. We selected a Frigidaire and called their tech support. They strongly recommended PSW over MSW saying a steady diet of MSW would shorten motor life. Our old inverter was smaller and getting tired anyway so we replaced it with a Magnum Energy PSW unit.

Many folks use the Samsung fridge (RF197 very popular to replace Norcold 1200 fridge) and Samsung says MSW is fine.

WheelingIt · 01-31-2013, 07:03 PM

Quote:

Originally Posted by smlranger

Many folks use the Samsung fridge (RF197 very popular to replace Norcold 1200 fridge) and Samsung says MSW is fine.

Exactly what I've heard.

All your electronics, TV and computers will be fine on MSW...we've been fulltiming for 3 years on MSW (with alot of dry camping) and no issues with any of these. They all have their own AC adaptors that convert the power supply anyway.

Where you run into trouble is with microwave ovens and such. They really struggle with MSW (the magnetron really has a tough time). For a residential fridge I would call and ask. Samsung seems to do fine (and I've met several folks who run them on MSW) but other brands may not.

Jerry J · 01-31-2013, 11:03 PM

4 batteries will fit in the tray but will probably be overweight. I'm going to try to add a picture of my AGM's that I added last year.

Luckiest Dreamer · 02-01-2013, 09:51 AM

I have been using the 2800W inverter that was installed by Winnebago and had what I considered a small understanding of sine wave! Your post made me do a bit of online reserch using Google. I suspect that the Pure Sine wave is the smart way to go. It looks like the most appearent problems would be with digital items like a thermostat or a digital radio or even the microwave clock. It seems a microwave itself may be one that causes problems. However the Modified type would power the frig, etc the longitivity of the appliance will suffer. That would make me believe that you either pay the extra today or eventually pay tomorrow!

WE expected to use the inverter to power the refrig as we travel. However unless you switch off circuit breakers that you do not want to power, things like radios and even your TV's will still use it as they always call for a bit of power. I suspect that the turning off of the breakers will soon be ignored so starting out with the proper sized inverter from the start would be smart.

Deucenut · 02-01-2013, 01:04 PM

You'll have to forgive my ignorance. But what is the difference between modified sine wave inverter and pure sine wave inverter? Why does one hurt electronics? Thx. I just want to understand the conversation.

smlranger · 02-01-2013, 02:28 PM

Quote:

Originally Posted by Deucenut

You'll have to forgive my ignorance. But what is the difference between modified sine wave inverter and pure sine wave inverter? Why does one hurt electronics? Thx. I just want to understand the conversation.

I'm no electronics expert so can't really answer your question other than my understanding is that PSW more closely mimics/duplicates what we get from standard 110v shore power.

However, you must have one of the coolest Toads ever. I would really like to see a pic of that '32 Ford.

wa8yxm · 02-01-2013, 02:33 PM

A lot depends on the printer...

Computer: Likely will not mind the MSW, the power supply is fairly rugged in most computer, plus many folks use a UPS with a computer and most of those are MSW when in inverter mode. If it's a notebook or netbook monitor the wal wart or brick temp the first few times you use it, Feel it every 5-10 minutes for the first hour, if it seems to be overheating,,, Then I'd worry.

Printer: Inkjet, no problem Laser... May object to inverter power.. Reason.. When the fuser activates, it can suck a whole lot of power and the inverter may overload.

Television (in fact all radio and audio gear) may not work properly, Possible issues include hum in audio, "Spaklies" on screen, "Watusi" effect (Screen does the hula) or simple no signal detected,, AM radio a very loud BUZZ, FM may work.

NOTE that none of these damage the units in any way (Save perhaps the loud buzz with the speakers on the AM radio).

Summary:

If it works, I would not worry about damage to the hardware, HOWEVER, epically audio/video gear may not work or may suffer "interference"

TheArnolds · 02-01-2013, 03:32 PM

Quote:

Originally Posted by ChiefJohn

Okay folks, preface it to say that I'm ignorant when it comes to inverters, appreciate the feedback/assistance -- we have the 2000w modified (quasi) sine wave inverter installed by Winnebago. I'm hesitant to use this inverter to power our computer, printer, TV, and soon to be installed residential refrigerator due to the possibility of damaging the electronic components. Do we need to replace this modified inverter with a pure sine wave?

Chief,

I have a 2000W Modified Sine Wave Inverter/charger (Magnum Energy, Inc) and we have a residential frig, convection microwave, 3 flatscreen TV's, etc. I work from the road so I have two laptops, printer, etc. My MSW inverter runs everything without any problem.

I hope this information helps!

Jack

dirko · 02-06-2013, 12:31 PM

Hi Ho: Maybe a few words about the difference between Pure Sine Wave (PSW) and Modified Sine Wave (MSW). Inverters work by switching DC so that an AC wave form is produced. As you probably know electronic switches are simplier and more efficient when they are either fully on (saturated) or fully off. MSW inverters work this way and essentially produce square waves instead of sine waves. There is some attempt to round the edges of the waveform by filtering, but the waveform is still more like a square waves than a sine wave. What this means is that the peak to average voltage is higher than for a sine wave. This higher peak voltage and the square waveform upsets some devices including some motors.

Pure sine waves were historically produced by using a tuned circuit, i.e. a capacitor and an inductor which were resonant at 60 Hz. Modern sine wave generators use Digital Signal Processing (DSP) devices that synthesize the waveform. However, getting large amounts of power requires rather expensive amplifiers. A PSW inverter gives power that has a waveform that has the lowest peak to average waveform possible (a sine wave). Some devices (but not many) like this waveform better than MSW. In the frequency domain a PSW is only one frequency while an MSW has the fundamental waveform plus odd harmonics.

As far as frequency accuracy is concerned there is no fundamental difference between the two. They use a crystal oscillator that is about as accurate as your watch (or maybe a little better). If one uses a more accurate crystal than another is may be a tiny bit more accurate.

If anyone has a question, I'll try to answer. For what it's worth, the power company produces PSW.