Inverter and Microwave Oven

Apparently yes but with efficiency penalties. For example.

Link Link

They don't appear to be damaged however.

I am not sure, but it could be that the microwave oscillator runs off a DC power supply in the unit, thus converting back to DC before oscillator should work OK, depends on noise maybe, because the AC frequency shunt on the DC power might not be up to the bandwidth required.

My answer: maybe, I give it a 75% chance of working OK with no damage.

Consult any online information or user's manual when in doubt.

The inverter generates a modified square wave, it will probably work ok. It may make a bit more noise, as someone else stated run it at lower power level. Several live aboards up here do it all the time. I don't recall the make, but a 2KW inverter will run a 1KW microwave Ours are 60Hz, you are 50 IIRC, that may be an issue. As you well know, there are inverters and there are INVERTERS. Most are not designed for marine use. As you are running 220VAC, you don't have the split phase issues with the associated grounding/bonding we have.

If you are using the batteries in parallel at 12 volts the amp draw will be over ~166 amps for 2000 watts....you should use as short of a run from the batteries to the inverter as possible, and have wire gauge large enough to handle that much amperage....2.0 should be enough for under 20'...

https://www.bluesea.com/resources/1437

https://www.amazon.com/dp/B016HFD86Y?psc=1

Behind every story is a untold part... In my case, due to the hurry in which I wrote the post this afternoon, I did not tell that I actually had used the microwave oven on the inverter a few times during the last months (only 30 sec´s or so to heat up a cup of coffee), besides being noisier than expected for a new appliance it seemed to work ok.

Last Sunday I programmed it to run 30 sec´s, it started ok, to completely die a few secs later. After a while it showed again a normal (lit) display. I tried to make it run one more time and the same happened again.

The repair shop guy said hat the oven worked this way because it was overheating due to a broken cooling fan. A safety switch prevented further damage. After replacing the fan it was in working order again.

He saw no relationship between the broken fan and the "square wave". On the other hand he said it was the first time someone told him about an oven used on a inverter. In his opinion nothing should happen to the microwave as all the electronic components run on 5V DC and the magnetron on 220V (the type of wave did not matter).

I left the shop saying I would give it a try again, he smiled and said: remember next Monday is a holiday and my shop will be closed......

http://yarchive.net/car/rv/inverters_microwaves.html

You probably have a modified sine wave inverter, should be fine...

What about getting a filter and reprogramming/replacing the inverter for a sine waveform? Square waveforms are acceptable for inductive loads (fans, air conditioning), but other types of electrical loads are not recommended.

If you can afford a boat, you should be able to get a proper electrical equipment as well.

Thanks for your input; and yes, I mainly use the inverter with inductive loads.

About affording a boat and buying "proper electrical equipment": in my opinion, there are two kind of boatowners: those who have a boat because they "have" to have a boat (and obviously can afford it like successfull entrepreneurs, rockstars and drugdealers), and guys like me, who truly like sailing and usually (like my case) have got a boat which is kept afloat not with the wallet, but with a lot of DIY, sweat and tears. So far a sinus wave inverter is last in my to-buy list.

OK, put the inverter output through an AC motor, that drives a 220 VAC alternator for "clean wave" service. I think that might even be nearly cost effective.

AC motor at 7 HP: eBay shows one at $210 USD

220 VAC alternator: Thermo King ~ $250 USD

Good luck. Still seems like a lot of money to run a microwave.

Better idea: Gas engine with silencer, high amp alternator, transformer.

This suggests it would be better to microwave when your batteries are near full charge.

Great article, thanks!

Perhaps just skip putting a microwave on your inverter by getting a 12V DC powered microwave.

See? TNC has it figured out for you already. If a truck driver needs one of these, you need one on your boat.

"If a truck driver needs one of these, you need one on your boat."

You mean I need a truck driver on my boat?

Right...what I meant was, yes, buy an inexpensive DC microwave oven.

just kidding!

That was good analysis of RMS power.

I have another idea. Rather than use this inverter (which OP will use because of cost), why not take DC power to run a DC motor-alternator (with 220 VAC output suitable for all AC power on board. It this cost prohibitive?

https://youtu.be/h41oenbUGsE

What I found on quick search for 4 HP DC motors, is that getting a good one under $1000 USD will be a real challenge, especially in the 12 VDC voltage. There are some higher voltage DC motors out there that might be less expensive. This does not include any consideration of cost of the alternator you attach to the motor. It also does not take into account the high level of introduced acoustic noise from the operation of said equipment. For reduction of irritant noise level, use the inverter with output conditioning.

Yes, it might be far cheaper to take the inverter wave-form and "tweak" it back to nearer a single 60 Hz or 50 Hz frequency using an oscillator circuit that is resonant at line frequency with a "reasonable" Q value. To do that, if you want to be a purist, you would capture the inverter no load, and loaded wave-forms, run FFT transform for frequency content, then do calculations of low pass filter networks to arrive at suitable components to clean up the output (at a lower power than what the inverter puts out, obviously), then run your microwave oven off the output from the filter.

I had a 2 burner coleman propane stove, with a barBQ mounted on the back on my boat, also propane...worked great...

...and a pump thermos....

What about a propane powered refrigerator? @TCMtech would love that. We have several of those down here every winter. They really save the batteries

I had a fridge, but it was for use in dock, shore power....for trips I used coolers and ice...

http://www.cruisersforum.com/forums/f91/propane-refrigeration-23229.html

I see a lot of these wind generators...usually paired with a couple solar panels...

http://www.cruisingworld.com/how/wind-and-solar-are-fine-osprey

right, wind generators and solar panels work great together, but a expensive battery bank is required to store all that energy... and also a sinusoidal wave inverter to run the microwave!