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Old 05-26-2018, 03:34 AM   #1
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Microwave starting amps???

Our new rv has a magic Chef 900w microwave. When I search it online I found two power consumption ratings.

Starting amperes = 38
Running amperes = 12.18

I am trying to size an inverter for microwave use. Running amps of 12.18 is about 1400 Watts. That’s ok

What the heck does starting amperes of 38 mean???


Thanks
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Old 05-26-2018, 04:54 AM   #2
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Quote:
Originally Posted by Bushfamily5 View Post
Our new rv has a magic Chef 900w microwave. When I search it online I found two power consumption ratings.

Starting amperes = 38
Running amperes = 12.18

I am trying to size an inverter for microwave use. Running amps of 12.18 is about 1400 Watts. That’s ok

What the heck does starting amperes of 38 mean???


Thanks
That is the surge power needed to start the microwave.

That is why I installed a 2200 Watt Pure Sine Inverter/Charger. I also doubled my battery bank.

Specs for the Samlex EVO-2212
Click image for larger version

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More info on my Inverter install:
Expanding compartment space for 2200 Watt Inverter/Charger
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Old 05-26-2018, 05:46 AM   #3
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Ditto Robert. That chart is very informative.

Microwaves need lots of power!

Lots of batteries. Bigger inverter. Big wire from the battery to the inverter. 2/0.

Inverter close to the batteries. Big fuze.
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Old 05-27-2018, 12:16 AM   #4
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So if the start up amps are 38, then that would translate to about 4,500 Watts right? So if u want to run the micro off the inverter, I need one that has a rated peak output of 4,500watts?

That just seems crazy.

Is my logic flawed?

I planned to buy a Prowatt 2000 but that wouldn’t even come close.

Thanks for the help
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Old 05-27-2018, 01:53 AM   #5
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So if the start up amps are 38, then that would translate to about 4,500 Watts right? So if u want to run the micro off the inverter, I need one that has a rated peak output of 4,500watts?

That just seems crazy.

Is my logic flawed?

I planned to buy a Prowatt 2000 but that wouldn’t even come close.

Thanks for the help
I checked the specs of the Prowatt 2000. It has a rated surge power of 3000 watt with maximum output current of 19.2 amps. see below:

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http://www.xantrex.com/documents/Pow...rter%20NA).pdf
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Old 05-27-2018, 07:53 AM   #6
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My son did some experimenting on this subject. He is building a stealth camper.

He used a good quality inverter(Xantrex 2000 I think)and followed the instructions on wire size and one twelve volt battery. No go.

Change from the recommended size 2 wire to 2/0 and a 400 amp fuze. Works great. He recommends 4/0 American made wire or welding shop 2/0. Foreign wire often use minimal strands and sometimes include the sheath in the size. Gag! Chinese crap.

His conclusion is better grade 2000 watts inverter, big wires minimum length to the batteries, and you can run most anything a while depending on the number of batteries. A/C likely not. We have 260 amps usable 12 volt capacity(4 six's). A micro wave uses 130 amps an hour.

It is that starting amperage thing. For micro seconds.

You are sort of right. I am going like my kid.

We want to run the coffeemaker. Less amperage though.
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Old 05-27-2018, 08:00 AM   #7
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Quote:
Originally Posted by Bushfamily5 View Post
Our new rv has a magic Chef 900w microwave. When I search it online I found two power consumption ratings.

Starting amperes = 38
Running amperes = 12.18

I am trying to size an inverter for microwave use. Running amps of 12.18 is about 1400 Watts. That’s ok

What the heck does starting amperes of 38 mean???


Thanks
the starting amps of a microwave is so instantaneous it will be no problem. Putting that info on the label causes more problems than the info its self.
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Old 05-27-2018, 07:07 PM   #8
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That is a 900 watt microwave? Where did you get your amperage data. 12 sounds a little high but pretty close, the 38 amp startup sounds extremely high. I wouldn't think a microwave would have a big startup amperage but I am no expert by a long shot. That is just very surprising. Just trying to educate myself and learn something new.
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