Microwave for a 1200 watt inverter?

[NaterPotaiter]

Hey guys, a while ago I built a 1200-watt system for camping. I would like to have a small microwave but I bought a 700 watt one from Walmart and it freakin pulled 1400 watts and tripped the inverter. And my bms is 1200 watts so a bigger inverter doesn't help. Anyone using a small microwave that draws less watts? Who knows, a more efficient 800 watt may only pull 1100 watts. I bought the cheapest one at Walmart.

 

[saggys]

I will be watching this thread as I only have an 1100 watt inverter.

 

[MisterSandals]

and tripped the inverter.

What inverter? Was it modified sine wave? If so, your microwave may not run well and use significantly more power.

 

[NaterPotaiter]

What inverter? Was it modified sine wave? If so, your microwave may not run well and use significantly more power.

It's a pure sine wave inverter. But even a good brand microwave is still inefficient. I've seen that in general, they will pull 1.6 times their cooking power. So 2 times for a Mainstays microwave is probably not unrealistic.

 

[RCinFLA]

The 2.4 GHz magnetron efficiency is between 60% to 85% depending on its load, which is the amount of energy absorbing material (presumably food) within the microwave oven.

On top of the efficiency is a startup surge current when first activated. This is caused by initial power transformer inrush current and charging of the high voltage power supply filter capacitor. This typically causes the initial 'grunting' buzz sound by power transformer which is overloaded for a short time period when first activated.

You can roughly figure needing an inverter of 2 to 3 times the surge capability of the microwave oven wattage rating.

 

[MrNatural22]

Try running your microwave at a lower power level. Most have levels of cooking power. Worked for my 700w. at 50% it had no trouble just takes longer to cook.

 

[RCinFLA]

Try running your microwave at a lower power level. Most have levels of cooking power. Worked for my 700w. at 50% it had no trouble just takes longer to cook.

That can help if you get pass the initial activation startup surge current. Same old story, low frequency inverters have a better chance at doing this than high frequency inverters.

 

[rcrracer]

Search this site for 'Panasonic microwave'. They make inverter microwave ovens.

 

[handinpalm]

Try running your microwave at a lower power level. Most have levels of cooking power. Worked for my 700w. at 50% it had no trouble just takes longer to cook.

I do not see how that will help. Microwave ovens change the power level by changing the duty cycle (Pulse Width Modulation, PWM). They just pulse the same high power (100%). So if anything, you will have a constant inrush current problem, instead of a one time inrush at 100%.

 

[NaterPotaiter]

Search this site for 'Panasonic microwave'. They make inverter microwave ovens.

Thanks, that would be good, but the lowest that line goes is 950 watts and that runs at about 1500 input watts. I just ordered this one https://www.amazon.com/Counter-Rota...fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840&th=1 One reviewer said it was pulling 1050 watts in his testing. So if this doesn't work, I don't think anything will. I saw on a review of a better 700 watt microwave that it was still pulling almost 1300 watts. We'll see. I will test it and report back.

 

[saggys]

Thanks, that would be good, but the lowest that line goes is 950 watts and that runs at about 1500 input watts. I just ordered this one https://www.amazon.com/Counter-Rotary-Microwave-WCM660B-Westinghouse/dp/B00BGTO1WC/ref=sr_1_3?crid=2FMMP506M4QZX&keywords=600+watt+microwave&qid=1673386842&s=home-garden&sprefix=600+watt+,garden,121&sr=1-3&ufe=app_do:amzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840&th=1 One reviewer said it was pulling 1050 watts in his testing. So if this doesn't work, I don't think anything will. I saw on a review of a better 700 watt microwave that it was still pulling almost 1300 watts. We'll see. I will test it and report back.

Nice find, please report back.

 

[MrNatural22]

I do not see how that will help. Microwave ovens change the power level by changing the duty cycle (Pulse Width Modulation, PWM). They just pulse the same high power (100%). So if anything, you will have a constant inrush current problem, instead of a one time inrush at 100%.

It works fine on my system. The quick inrush doesn't trip the breaker anymore on my 1500w inverter using a 100ah lifepo even though the nuke cycles on and off more frequently.
Try running lower power and see if it works for you.

 

[Koldsimer]

An inverter microwave will allow you to run at a true 50% (or any other percentage) power while a normal microwave run at 50% power will cycle full power on and completely off for equal amounts of time.

Maybe buying an inverter microwave and figuring out what power output is the max your inverter can handle is an option. They have several inverter microwave options in stock at lowes last i checked. IIRC panasonic sells a 900w unit at lowes.

 

[rcrracer]

I went to the Panasonic site and looked up the amp specs on about all the microwaves. The 1250 cooking power ones are the most efficient with their 0.8469 PF. The 1200 watt cooking power are next with 0.80645 PF. The 950 watt cooking power, 1224 va SD372SR has a PF of 0.77614. The SU63MS and SU656B have respective PF of 0.70513 and 0.67901.

 

[Bluedog225]

Thanks, that would be good, but the lowest that line goes is 950 watts and that runs at about 1500 input watts. I just ordered this one https://www.amazon.com/Counter-Rotary-Microwave-WCM660B-Westinghouse/dp/B00BGTO1WC/ref=sr_1_3?crid=2FMMP506M4QZX&keywords=600+watt+microwave&qid=1673386842&s=home-garden&sprefix=600+watt+,garden,121&sr=1-3&ufe=app_do:amzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840&th=1 One reviewer said it was pulling 1050 watts in his testing. So if this doesn't work, I don't think anything will. I saw on a review of a better 700 watt microwave that it was still pulling almost 1300 watts. We'll see. I will test it and report back.

Bump. How’s it working?

 

[DrZ123]

Any update on an efficient off-grid microwave?

 

[obd.tech]

Lowest power 240v microwave I've found is a Daewoo Qt 14L 600w output, draws 1000w which is about 95/100A from a 120ah 12v LFP into a PSW Reliable brand inverter. Works a treat
(Also branded as other makes)

 

[sunshine_eggo]

Any update on an efficient off-grid microwave?

No. Microwaves use 1.6X their rated power output.

Standard microwaves at reduced power simply run 100% less time, e.g., 50% power means 100% output 50% of the time.

Panasonic Inverter microwave is no more efficient, but it actually runs at a lower power. If you set it for 50% power, it runs at 50% output still consuming 1.6X the output. The benefit is a legitimate lower output/consumption at reduced power settings.

 

[DrZ123]

I ordered this one, will see how it performs. Figure it's only in use for what, 5-10mins MAX a day?

https://www.amazon.com/gp/aw/d/B00785MVRA?ref=ppx_pt2_mob_b_prod_image

 

[cs1234]

No. Microwaves use 1.6X their rated power output.

Standard microwaves at reduced power simply run 100% less time, e.g., 50% power means 100% output 50% of the time.

Panasonic Inverter microwave is no more efficient, but it actually runs at a lower power. If you set it for 50% power, it runs at 50% output still consuming 1.6X the output. The benefit is a legitimate lower output/consumption at reduced power settings.

That's not the only benefit. They also claim it *cooks* your food better / more evenly than non inverter microwaves when both are running at less than 100% output.