I'm a cross country truck driver and use the microwave daily. I was buying a new microwave every 3 to 6 months using a modified inverter and it didn't matter what brand microwave it was either. Once I got a pure shine wave inverter, my microwave was quite and heated my food, drinks a whole lot quicker! That was over 2 years ago and still using same microwave! The extra money to purchase a pure sine wave inverter pays you back quickly!

I've been watching your videos for hours now and you've helped me greatly. Thanks!

Your videos are very informative . Thanks for posting

The buzzing sound you hear using the modified-sine-wave inverter is coming from the microwave's power supply transformer due to odd harmonic voltages (3rd=180Hz, 5th=300Hz...) on the modified sine wave output. This will cause harmonic currents, which will cause heating in the microwave's power supply transformer. It would be interesting to measure the value of the harmonic voltages and currents and estimate the total harmonic power going into heating the power supply transformer. If this is over about 50Watts, I would say you probably should spring for a True Sinewave inverter.

Great to see a new video ***** all the best!

Just to mention that the measuring devices you used are based on sinusoidal wave forms. Measuring square waves is quite different (True rms).

Most helpful explanation of critical technical puzzle.

Thank you very much for this video which has answered a very important question for me.

Excellent testing report. Thanks.

Great video. Thanks! Would you definitely want a pure sine wave for a refrigerator or would you use the same approach regarding the value of the refrigerator to decide?

When I ordered my power jack inverter I got ripped off. The Hot Chinese chick in the picture wasn't even in the box!

I always enjoy your scientific analysis, and have incorporated some of your ideas and cautions into my transfer switch. Thanks for your informative videos.

LOL. "This is a thing..." Great video, as always.

Interesting video, thanks for the upload.

Great video, very informative. Thank you

I'm wondering what the results of power consumption would have been, if you had taken power factor into the calculation, and measure in volt amps. Just a thought, but another great video.

Impressive information. Thanks.

This might be a dumb question, but if your power company is running 120v (like mine) and the pure sine wave inverter is 110v would it change the water temp any over the 2 minute cycle?

Answered all my questions

Thanks for sharing, gives another look at the subject. Some things I experienced: - with my pure sine wave inverters from Victron Energy, I get a nicer looking sinewave most of the time then on the normal 'street connection' that is running here, especially when not using full-loads. When I use only 1000Watts on a 1500 WA inverter for example it stays in a nice sine-wave. - with some cheaper 'pure sine wave' inverter from Conrad (rebranded I think from Voltcraft), it is kind of a modified sine-wave under low load (like a 50 Watt tungsten lightbulb), actually looking a bit like a sine-wave. But still isn't as is getting very clear under the scope. Actually this inverter killed my energy-meter pretty fast...electronic components... - modified Chinese kind of 'sinewave'... it is more of a block-wave with spikes. Even worse then on a couple of UPS-es I have (they are also modified sinewave ofcourse). Not really a 'modified sinewave' but just spikes and longer taking spikes to make blocks when under higher load. With a large inductor/coils you are getting more of a sinewave. Power-meting on the output of a inverter is not showing you something real though because they are made for and calculate for the results of a sinewave, so the values are incorrect. You will probably get a better result when measuring on the 12 volt inputs Because of the high pulses, a microwave can be the worst kind of load for an inverter, the spikes are getting through. I think I noticed your inverter flashing like 'overload' in your video because of this.

When looking up types of inverters, I got the following 2 classifications: 1) pure sine wave VS modified sine wave and 2) microinverters VS power optimizers VS string inverters Do these classifications interlap. For instance, can I have microinverters that are also pure sine wave inverters?

I was reading about some inverters that have strapping options for 110 vs 115 vs 120v. Maybe that 5000w sine unit has such an option?

I recently bought a couple of deep cycle batteries and a couple of inverters. One is a 1000 watt pure sign wave inverter and the other is a 3000 watt modified sign wave inverter. My 600 watt microwave is an 20 year old unit. Both inverters showed that the microwave oven was drawing about 1000 watts. The puresine inverter couldn't handle the load and I switched to the modified sine wave. I know that microwave ovens are inductive loads, but a 40% increase in power usage was a surprise. What is the manufacturer stated wattage of the mictowave oven you used in the video and how old is it? Would newer 600 watt ovens have power correction to reduce the apparent load?

Thanks for this! What's the make and model of the modified sine wave inverter? My microwave on regular ac power draws 1540 watts so I think it's the same as yours and would work with that inverter too.

Thank you! You explain very well your discoveries, etc., in your videos! You do not waste time! And that is great!

So the modified sine inverter uses PWM duty cycle and True RMS AC voltage is lower?

That appears to only be the microwave oven's power transformer lamination buzzing from the quasi-sine' s high harmonic distortion. It keeps time because there's a separate low voltage DC power supply powering the low level stuff, all of it integrated into a chip.

Hello there... Will a modified sine wave inverter runs a AirConditioner??? My aircon constant draws 2A in 220v plug in the wall, how much watt MSW inverter i need to buy???

I expect an inverter based microwave would be more efficient than a traditional transformer based microwave on modified sine wave as it doesn't use a big transformer but a switching power supply like a computer or TV which rectifies the incoming AC to DC straight away.

There is something I noticed in modified sine-wave inverters. I used to have an 2000 watt modified inverter to power a fan motor and that 100 watt motor would hum very bad. But powering the same fan motor with an 4,000 watt modified inverter, the motor would not hum at all and it was like the motor was running of the power grid. Could you try the same experiment with an 4,000 watt modified inverter to see if this would make any difference? I am just wondering.

Just curious -- you mentioned that the microwave is a 1000W model. You were dissipating 1490W off the pure sine inverter. Do you know what the power draw spec is on your Whirlpool? It would be interesting to see how closely your KillAWatt reading matches the back panel.

Thanks for the videos; I bought my modified sine wave inverter on your recommendation and it has paid off. I've been wondering about the ability of the modified sine wave inverters to run electronics. I am particularly interested in running a bread maker. Do you think they have any electronics beyond the clock that modified sine wave might run improperly or ruin?

I would have liked to see the Kil A Watt P.F. Power Factor and VA volt amps measurements for each as well.

I have a 2500 watt Xantrex Freedom 458 modified sine inverter/charger that came in my 2005 Fleetwood Bounder RV. Today we were using a fan with the inverter and it stopped working after a short time. Not sure how long because I was asleep. I plugged an identical fan into the outlet and it ran for less than a minute before stopping. Now neither fan works when plugged in at home. Is it possible that this modified sine wave inverter burned out the fans? They worked fine while at home and when using shore power or generator power. They are brand named Sunter and came from Costco a few months ago as a package deal of a floor standing fan and a tabletop fan.

I've been trying to find out whether to pay double for a pure sin-wave converter for using power tools with a caravan battery. I think you have convinced me its worth spending the money. I do wonder what a less expensive pure-sin inverter would be like (1000-2000W range rather than "5000W"). would it make much difference?

my microwave sounds like its going to explode on my mod sine inverter!!! could i get a cheap microwave thatll work on it instead?

Great video! I like the actual application to answer a question, thanks for making this video. On a side note, any idea why I can't find an OSP tiger claw inverter anywhere?

Wow, I'm really shocked at the result of like a 10' difference. I was wondering what the transformer temp difference would have been but now dont really care as its got to be higher on the modified... I must admit I only run appliances that are usually swichmode powered, like PC's and laptops, so the wave shape doesnt bother them at all, i had an inverter go wonky and it was putting out dc not ac and i didnt notice for months till i plugged in something with a transformer supply and it would not work...

modified sine wave is 1100w for 2 minutes. 1110w/60 seconds =18.33w supplied per minute for 2 minutes to heat water to 40C, using total of 36.66w power. Pure sine wave is 1500w for 2 minutes. 1500w/60 seconds=25w supplied per minute for 2 minutes to heat water to 50C, using total of 50w power. Modified sine wave in same time heated the water to an 80% temperature value compared to the 100% for pure sine wave. This is 1w for each 1 degree Celcius for the pure sine wave, and 0.92w for each 1 degree on the modified sine wave. The unexpected discrepancy making the sine wave seem more efficient may be due to the extra power required to use a 5kw inverter than a 2kw inverter, due to differing heat loss from the inverters, also efficiency of conversion should be included. A more accurate picture would be if the time requirement was ignored and instead both were heated to 50C and then the total wattage used by both to bring the water to the same degree Celcius was used. My calculations says it would take 2 minutes and 24 seconds (2.4 minutes) for the modified sine wave inverter to also reach 50C temp in the water, and the use of 44w power compared to the 50w of power the pure sine wave inverter used. Another way to test better would be if both inverters have the same Kw rating, thereby reducing efficiency differences due to different transformer sizes used in each inverter.

Hi my friend, What doyou think about the whisler xp2000i iverter,,,,,,,thanks in advance

Thanks for the video. I was wondering why the microwave drew 500 less watts from the modified sine wave inverter?

thanks for all your videos. Why is it so hard to put out a pure sinewave? even if one starts with a square wave, it's not hard to filter that low power signal with a high Q bandpass filter using a couple op-amps. isn't it? then amplify the signal to get the derired output power. Why are there still modified sine wave inverters? is it that much cheaper not to do it?

good test

Can a PC be damaged by using a modified wave inverter to power it?

by the way how did you remove the tatoo from your face

Thanks again for a very helpful video! It inspired me to buy an open-box Insignia microwave from Best Buy for $40. I connected it to a MSW inverter and it didn't make any noise at all and the clock/timer worked without issue. The only difference is that it appears to function with reduced power. It took a little more than twice as long to boil a cup of water. So, I could install it in my van, but a JetBoil or a $25 Japanese butane stove would boil water a lot quicker and would take up less room. The only inconvenience with using a JetBoil or a butane stove is that you need to have a door open. Oh, and you also have to be careful that you don't set everything on fire.

Hi Knurlgnar, did you measure your voltages and power in RMS values. In other words does your meters measure the voltages and the powers independent of the wave form. Your a clever guy so i assume it does. If that's the case the the power difference between the two power measurements are not and indication of inefficiencies. Just a note form my side. It seems that you have calculated it through because you come out at a difference of 10% and that's not what the power measurements indicate. I come to more of less the same numbers. By the way nice experiment

Kindly do a review on reliable power inverter

Could you detect a "dirty" power inverter with a power monitor that shows the line frequency? (Like a Kill-a-Watt monitor connected to the inverter?) Would you still get a nice, steady 60khz display or would there be enough "jitter" in the reading to see? (for those of us who don't have an oscilloscope or who want to blow up our microwaves. :) )

Great vid.

Hello, I have an Auto AC Inverter Traveller's Power 5000W, Model No. 2012 which I want to use in the house, unfortunately in Nigeria we use 220V. Also do I need a separate charger for the battery or charger inbuilt in the inverter?

Thanks man!

thanks for the video

Hello, wasn't sure if to ask this here or on the ups conversion videos. It seems modified sine wave is more trouble than it is worth Vs pure sine wave, but pure is a fair more expensive. Could a modified sine UPS be converted to be a pure sine inverter? Without touching wattage capacity, just make it pure sine. Reason to ask: I can get backup ups's (modified) for a tenner and the smart ups for 100-150 (both working second hand). Thank you.

Thank you stu

I bought a 1000w Bestek modified inverter before I learned about the pure sine models. Which brands do you personally like in a 2 or 3000w pure sine inverter for 2017?

Hi, im planning to power two led smds 30w each floodlights with a 300w modified sine wave inverter. Will i encounter any problems?

Microwave ovens seem to run ok on MSW, but my induction cooktop does not heat. I've tried two different cooktops (but both NuWave PIC) on two different MSW inverters, one a 2500W and the other a 2000W. The cooktop readout LEDs light, but it will not heat anything when connected to a MSW inverter. I suspect it needs some out-of-phase magnetizing VARs not available from an MSW inverter. Any confirmation or other explanation?

Great video.

I had a modified-sine-wave inverter powering my microwave in my RV and by about the 20th time fried my microwave which was brand new ...

Hello, i think we should also consider the fact that the invertor are not of the same wattage.

How many watts is the microwave?

can i have a game pc run of a battery back up pure sine wave. that is plugged in to the wall, of an off grid modified sine wave home?

I wonder the type of ur microwave..is it a inverter microwave or a transformer microwave..i need the answe...cause i want to buy inverter for microwave

Great video thanks

Thanks for the video. You answered my questions. This was a huge concern for me until I realized that I barely use my microwave. Now I'm not even sure why I have a microwave oven. Problem solved!

Hi, Any one know the practical difference between High frequency and Low frequency power inverters? Specially related to loading of inducive and other loads.

does that mean that a toaster or a coffee maker will work also on a modified converter?

Would be interesting to see this test using one of today’s inverter microwaves. The humming problem should be gone and the performance gap may be negligible. But I’m curious about the effect of moving from one type of difficult load (highly inductive) over to another type of difficult load (highly capacitive)..

I tried a modified sine wave inverter on my 1000 watt microwave. It only put out 660 wats . On house power was 1540 watts. Also inverter beeping due to microwave overheating and was very hot. Would using better cable fix this? Was only 11 gage. Toaster and vacuum perform perfect with very close watts as house power.

Was the clock affected by the modified? Was a full 2 minutes or was it not?

seems that I hear that the microwave can't get enough power to run off a small off grid setup, this would explain why since many will, like myself, will but first the modified because of price, later I only buy the pure sine waves that I use now.

If I charge my ebike with a modified sine inverter, can this do any harm to my ebike battery or just to the charger as it would heat it up unnecessarily? Thanks for the great video!

Im wondering why the small inverter witch is way to low watt to run that big microwave didnt shut down naturaly a 5000 watt of any kind will outdo a 1500 i got a 1100 watt ouput inverter krieger that will run mine i even ran my hole trailer of it .

im surprised nobody has drawn the similarities between inverters and amplifiers yet... But I think the microwave doesn't like the modified wave for the same reason speakers dont like a clipped signal because a transformer is just basically a coil wound in a different shape. and when you clip an amplifier the sound wave starts to turn square like a modified sine wave

On the fence about spending an extra $100 ($80 vs $180) on my simple setup for pure sine vs modified sine wav . Also finding Inverters just don't last very long for me.. wish they were generally more robust. My battery Is my starter 70AH 120RC. I run power tools and appliances 500w to 1000w, but need to run a freezer for 8 hours while a 200w solar panel feeds my battery through a MPPT controller. Just had my 1200w modified sine inverter go bad after an accidental short.. they are so sensitive. Somebody wrote a review on my inverter saying the inverter was eating 200W to power a 100W in devices...

Speaking of PSW inverters.... have you tried looking at the wave form from a modified sine wave inverter at the output point from a transformer like from a laptop? My Mascot 600watt pure sine inverter runs just fine but I had a guy ask me if plugging in a transformer for a laptop didn't smooth out the wave form from a modified sine wave and I couldn't really give him a definitive answer other than modified sine wave inverters and computers are a bad thing.

Thanks for sharing. have an identical looking multimeter. how did you use it to measure temp on the 200 Volt scale?how did you measure 122V? was it from a different output? the modified sine wave inverter did not put out 122 Volts and your measurement was incorrect. rms is rms. you called ur meter reading rms. soooo... it was not the inverter. it was your reading. and your inferences about efficiency also are incorrect.

Excellent video! Showed what has been exactly my experience. (Plus the weirdness in MSW while charging/powering computers and other electronics.... especially those with touch-screens.) Which is why I'm going to PSW.

thank you

Can you run an air conditioner off a modified sine wave inverter without burning it up?

hey buddy, you have to use to microwaves, cuz, when u first use it , i till not warm as strongs as the last use,

You need to be comparing VA between the two microwaves, not watts. On another note, I have a cheap 1500W modified sine inverter from Harbor Freight that outputs such poor quality power that my kill-a-watt didn't read properly.

The voltage reading of the modified sine inverter will only be accurate with a true RMS meter!

u should do an equal power inverter.

Informative thx

good video

Appreciate the video... But, not sure 1500w is enough to run a microwave to its full potential... I have seen advice to use an inverter that is double the microwave rating... Not sure if this had an effect. The microwave did work without blowing a fuse or safety shutdown, which i find surprising.

Thanks knurlgnar24, I love your videos.

Hey, thanks for that video! LOL i ran a GenPower Generator 3kv (Pure Sine Wave) Bought a Chinese Induction cooker rated at 2000w yet, when i ran it max , (with an extension cord @10 METRES), the generater showed up as 1.8kw running the induction cooker at maximum. so, my question is, is the generater displaying incorrectly, or is the induction cooker under rated?. :) Also, i see lot of so called sign wave inverters advertised on EBayyyyy, yet on the photos you can see the array of MosFets aligned on giant heatsinks... I believe a TRUE Pure Sign Wave Inverter to be constructed of a core of Ferrite wound by quality insulated copper windings? Correct me if i am wrong? Mick L.E > time for the U.S.A to go Metric ;) cheers!

great video.. It would have been helpful to measure the DC current and voltage in to each microwave, becuase the would be the truest measure of energy required to operate the microwave. The reduce output of the MSW might be a limitation of the setup.

Hello, I just feed my electricity into the floor of this house with a 1500W pure sine. However, that is not even enough for an 800 watt microwave. Can I simply use a 3000 Watt Mod sinus instead? Everything depends on it, computer, kitchen, etc. When I see the video, mod sinus is even better because it consumes less watts^^

Somehow I don't think the Kill A Watt was designed for "modified" wave forms. This makes all results on the modified sine converter suspect.

It should be noted that a MW oven is sensitive to, and it's output varies with, the peak voltage of the supply. This should not vary much with a sine wave inverter ("pure" is a redundancy- marketing hype. It's either a sine wave or it's not). But peak voltage absolutely varies with load and battery voltage with a modulated square wave inverter (there's nothing even close to a sine wave coming out these- "modified sine wave" is a joke, more marketing hype). If you raise the DC voltage going to the MSW inverter, you will also raise the output power of the MW it's supplying.

Thanks

Love those 24-dc1 batts. Best bang for your buck. I use them in my locksmith geddup with a battery isolator.

In Amplifiers for guitars i listen to extra buzz sounds....i guess its due the aliexpress 15€ modified sine wave inverter... i had no idea, learning everyday...pure sine wave inverters do not exist for 15€ though.

if the microwave was an 'inverter' type, it wouldn't matter.

can you use a domestic power meter to monitor the power supplied from a modified sinewave inverter?

See this video for simple way to reduce microwave wattage: ukposts.info/have/v-deo/cHN4iJhuoW-ElH0.html Parts cost $10-$20 USD as of May 2022.