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Microwave on inverter
#1

So I was trying for the first time to use my microwave while on inverter and it wants to run for maybe a minute or so and then stops.  Light flicker on other electrical items like the fridge and then everything stays powered up.  You can then try it again for another minute, etc.  Suggestions?

Brad Aden
2003 Newell #653 Quad Slide Cat C-12 engine
St. Louis, MO
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#2

Brad,

How is the power restored?

Is the entire MW (clock too) dead?

What does your panel say for Amps when it’s on?

Any other 220v loads on at the same time?

From a distance, this sounds like a Load Management issue; especially if the power to the MW is “magically” restored after waiting a bit.

Steve & Janice Vance
2015 Newell #1524
Glendora, CA
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#3

(03-22-2023, 09:12 AM)CaptainGizmo Wrote:  Brad,

How is the power restored?

Is the entire MW (clock too) dead?

What does your panel say for Amps when it’s on?

Any other 220v loads on at the same time?

From a distance, this sounds like a Load Management issue; especially if the power to the MW is “magically” restored after waiting a bit.
Power is automatically restored in a second or two.  Flickers just a bit and then continues on.  Microwave kicks it up to about 170A for a minute or so until it shuts off.

Brad Aden
2003 Newell #653 Quad Slide Cat C-12 engine
St. Louis, MO
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#4

Brad,

As far as I remember you have a Magnum 2812 inverter.  The Magnum is rated for 3900 Watts (Volt-amps) surge.  This means that the maximum AC surge load is 3900/120 = 32 Amps.  

Since I usually went ped-to-ped and almost alway ran the generator…the microwave on battery was not an issue. 

I did a quick check on microwaves and most seem to pull about 12-13 amps. 

So…unless you have something like heaters going….the inverter should be able to handle the load.

Do you have an AC clamp on ammeter?  If so…you can get an AC load splitter and measure exactly how much draw is coming from the microwave. 

https://www.amazon.com/gp/product/B003A0...UTF8&psc=1

   

Something else you might want to consider is to get a second inverter and stack them.  I dont know but I suspect that you could double your amp draw capacity*.  *double check before you take my word.

Bill

Bill Johnson
Birmingham, Alabama
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#5

(03-22-2023, 10:03 AM)bikestuff Wrote:  Brad,

As far as I remember you have a Magnum 2812 inverter.  The Magnum is rated for 3900 Watts (Volt-amps) surge.  This means that the maximum AC surge load is 3900/120 = 32 Amps.  

Since I usually went ped-to-ped and almost alway ran the generator…the microwave on battery was not an issue. 

I did a quick check on microwaves and most seem to pull about 12-13 amps. 

So…unless you have something like heaters going….the inverter should be able to handle the load.

Do you have an AC clamp on ammeter?  If so…you can get an AC load splitter and measure exactly how much draw is coming from the microwave. 

https://www.amazon.com/gp/product/B003A0...UTF8&psc=1



Something else you might want to consider is to get a second inverter and stack them.  I dont know but I suspect that you could double your amp draw capacity*.  *double check before you take my word.

Bill
I do have a clamp on amp meter.  Just by looking at my Magnum screen I'm pulling 13A as a baseline.  Fridge kicks on and that take me up to 27A.  When the microwave was on (I'm not sure if the fridge was cycling or not at this time), but when the microwave was on that took me up to 170A for a minute until it kicked off.

Brad Aden
2003 Newell #653 Quad Slide Cat C-12 engine
St. Louis, MO
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#6

170 Amp AC? Or DC?

If 170 amp dc… then 170 Amps x 12VDC = 2040 Watts (DC)

2040 Watts (DC) / 120VAC (ignoring efficiency) is about 17 Amps (AC).

That does not sound too far out of line.

Can you find any error messages on Magnum Panel?

https://www.magnum-dimensions.com/fault-...tr-remotes

Bill Johnson
Birmingham, Alabama
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#7

Hmmmm,

If there are other loads on the inverter when you turn on the micro, it can drop the voltage below the voltage cutoff point. That cutoff point is adjustable. If you can scroll through the menu until you find the LBCO, and then monitor the voltage on the Magnum screen while starting the microwave.

This is a bit of a tricky problem in that the inverter cuts out for second, then resets automatically when the voltage comes back up, and to my knowledge leaves no record of an error.

I know for a fact, even with my massive Lithium bank, that I cannot run the microwave AND the water pump at the same time without causing this fault to occur. Rhonda has learned not to turn on the faucet if the oven is running if we are on battery power.

Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home Cool )
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#8

Our inverter also supplies voltage to the refrigerator so if you still have the old Amana and its running your over your limit on the inverter specs, one thing you might consider is a new inverter microwave, they draw less current because they do not have hat big heavy transformer for the magnetron.  I know you all might be tired of me saying inverter all the time but it truly is a current saving technology. Yes one device at a time is the trick.

1999 45' with tag axle, #504 "Magnolia"
Gravette, Arkansas
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#9

To add to what Richard said.

The headhunter pump is rated at 9 Amps AC.
Typical Microwave is 13 amps.
Typical Refrigerator is 6 amps.
Typical LCD TV would be around 1 amp.

Also…The 3900 watt (32 amps) specification for your inverter was the SURGE value. Steady state is 2300 Watts (19 amps).

So…running the microwave and fridge at the same time is iffy….and like Richard said…the headhunter and the microwave are not gonna work together.

I like Jack’s idea of replacing appliances with more energy efficient versions if you are gonna be running off batteries. Using the 12V water pump is a start. Increasing the inverted power is also a solution. I guess that is why some of the newer coaches have two inverters.

Bill Johnson
Birmingham, Alabama
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#10

I used a Magnum 2812 inverter in my last coach for 7 years. No problems running everything, refrigerator, microwave etc.

I would run an extension cord to the microwave and check it with a different power source.

Jim
2014 Newell Coach 1482 Mid Entry 45'8" Valid Slides and Valid Levelling
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