Modified sine or true sine inverters?

[The Danes Are Coming]

We are still having a few problems with our electrics and after having taken most everything to pieces and tightened every nut and bolt in the RV, we have come to the conclusion that it could be our inverter that is playing tricks on us.

For that reason we probably will be going to a shop that can test our inverter, and in order to be prepared for the worst, I have started looking at prices on new inverters.

We have a modified sine inverter installed at the moment. I keep hearing that true sine inverters are "the bee's knee's" and I have also read how the modified sine inverter do not produce a true sine wave. What I have yet to find out is why I should pay about 75% more for a true sine inverter. It would seem that both types will supply my bulbs, TV, microwave etc.. with ample electricity. I assume that I will not get a better light, a better TV picture or a better cooked roast with a true sine inverter

Please enlighten me

[cbeierl]

Quote:

Originally Posted by The Danes Are Coming ... I assume that I will not get a better light, a better TV picture or a better cooked roast with a true sine inverter Please enlighten me

Actually, the microwave will certainly be happier with a true sine wave inverter (whose output is just like that produced by the power companies on the 'mains'). It will take a bit longer to cook things using modified sine wave and may shorten the life of the microwave. Some small electric chargers, electric blankets, etc. may not work properly with modified sine wave and may in fact burn out.

[wardy]

Seems like a bunch of inverter issues lately. Anyway cbeierl is right on. I have both in my coach. A true for the resi refrigerator and modified for all else. If you don't dry camp much then true may not be worth the difference for most needs. But anything with a transformer or AC motor will run hotter thereby shortening the life. Some electronics are also sensitive to modified SW as it is just not clean AC (harmonics etc).

[docj]

A modified sine wave inverter (MSW) produces a square wave not a sine wave. The voltage reverses like it is supposed to 60 times a second but it is not a smooth curve. However, whether or not this has an effect on any particular device is not something that can be predicted or generalized.

IMHO it is far too simplistic to say that "all" microwave ovens will do better with a pure sine wave or that "all" refrigerators must have pure sine waves. Many devices these days convert the AC power to DC inside the device so they don't care about MSW inverters since once the voltage is converted to DC it doesn't matter. Samsung refrigerators work fine on modified sine waves as long as the inverter can deliver the required starting current; I know--I own one. Our MH had a factory installed microwave that was wired to run from the factory-installed modified sine wave inverter. Of all the devices in our MH, the only one that I know doesn't work with the MSW inverter is our counter-top induction burner. If I was starting from scratch I would buy a PSW inverter, but so far my MSW is doing fine.

[wa8yxm]

"It would seem that both types will supply my bulbs, TV, microwave etc.. with ample electricity."

Bulbs (Incandescent) are basically resistors and thus work just as well on MSW as on TSW or for that matter DC direct of the proper voltage. ALL they about is the "Area under the curve" or in easier language the RMS voltage.

Florcesent, LED and other types of lamps are more sensitive to waveform. There is a thread about an LED night light that caught fire on MSW.

Microwaves also are Peak Voltage senistive, and thus do not work as well on MSW (For the most part, Panasonic makes an exception to that rule)

TV's may or may not work properly on MSW

Clocks, Timers and any device with ELECTRONICS likewise.

Coffee pots: If they have Electronics may not work properly on MSW, if they are basic water heater type (Just a resistor, thermostat, switch and indicator light) then see light bulb.

There is a long list of "Might or might not work or may work differentlly) for MSW

For True sine wave,, the quality of the power out is AT WORST, the same as shore power,, (NOTE, this would indicate very very very good shore power) another way of saying it is "The quality is perfect" Shore power is not usually that good.

Years ago I was looking at a "power line conditioner" This was an non-interpretable power supply and filter.. The demo unit used a dual trace scope and a noise maker.

Sitting there it normally had a nearly perfect sine wave in (Shore power) and a perfect sine out (TSW inverter) The defects in input were not really visible at the resolution of the scope.

you pressed the NOISE button and the input went crazy.> The output never changed.

The "Conditioner" considted of 3 parts

A smart converter, a battery and a TSW inverter

NOTHING is better than a TSW inverter which is large enough.

The only things that won't work properly with one.. Are simply too big for it.

(IE a 3,000 watt motor won't work on a 2,000 watt inverter)

[frankdamp]

Anything with either an inductive load (transformers, motors) or a capacative load, will be uncomoftable with anything less than a "true" sinewave. The vast majority of consumer electronics is low voltage DC within its cicuitry and has a transformer-rectifier as its input.

You're best option is to get devices that list input power as "100-250 Vac, 50-60Hz". They will run on a typical US RV's generator or on shore power with no problem. Resistance loads (heaters, curling irons etc.) can handle the less-than-pure sine waves just fine.

[bluepill]

I try NOT to use my Factory installed MSW to power my Factory installed microwave. The increased level of noise generated by the microwave when on inverter makes me worry. Both Factory installed TV's and DVD players seem happy on the MSW.

To the OP - What problems are you experiencing? How long? Only on inverter power?

[sparks1032]

I have been thinking the same thing as our "stock" system is about to croak and are looking to upgrade and not sure of how much we want to spend on this. I think price needs to be considered more for us as we need new batteries, inverter, wiring and monitoring devices. For you i would spend the extra money and get the pure sine wave and put it to rest!

[The Danes Are Coming]

Quote:

Originally Posted by bluepill To the OP - What problems are you experiencing? How long? Only on inverter power?

It started out as complete power cuts lasting a fraction of a second. This would restart our DirectTV receiver and cancel our electronic clocks on f.x. the microwave. It did not effect our surgeprotector so this didn't reset. We very regularly experience ALL light (110VAC and 12VDC) flickering.

Then a few days ago all power went out and our Magnum Energy remote displayed "DC overload" and the red fault button was lit. We reset the inverter and power came back on.

We have checked and tightened every nut and bolt in our electrics. Surge protector and ATS have been disassembled and checked. Yesterday I re-tightened everything in the battery room.

I have been in contact with Magnum Energy who responded IMMEDIATELY to my question (great service Darren Massey ) and they suggested, amongst others, a trip to one of their dealers to have the unit serviced. This may be our next option.

[The Danes Are Coming]

Quote:

Originally Posted by sparks1032 I have been thinking the same thing as our "stock" system is about to croak and are looking to upgrade and not sure of how much we want to spend on this. I think price needs to be considered more for us as we need new batteries, inverter, wiring and monitoring devices. For you i would spend the extra money and get the pure sine wave and put it to rest!

I have Googled prices on Magnum Energy inverters and all suppliers seems to have pretty much the same prices except for this one. Check it our if you end up needing a replacement.

[NoMoreAZ]

Quote:

Originally Posted by The Danes Are Coming I have Googled prices on Magnum Energy inverters and all suppliers seems to have pretty much the same prices except for this one. Check it our if you end up needing a replacement.

The site you referenced is for Solar PV, NOT RV and Marine applications. Whole different animal. You need an inverter for RV applications.

[Bill Adams]

Be sure to check out Donrowe.com Power Inverters and Accessories by Cobra, Xantrex, Wagan, Magnum Energy, Power Bright, Samlex, Voltec, Whistler and Goal Zero - DonRowe.com - Index as they are the leader in inverter sales and service. They have excellent tech. support after the sale as well.
As to MSW or PSW, I would not replace a working MSW just for the sake of replacement but it I HAD to replace my inverter I would certainly opt for the PSW even if the cost was somewhat higher.

[Perry White]

I have a Magnum modified in my coach and I cringe every time my wife lites off my GE microwave. Takes twice as long to cook and it sounds like it's going to throw the driveshaft.

[Perry White]

Also, Magnum people are great to deal with.