Inverter question - and my system plan

LaneW said:

I am considering buying a 2000 watt inverter. Looking at Renogy, but I don't find that Will has reviewed this one - Hoping for feedback on my plan, which is to install 2, 100 ah SOK batteries in my truck camper with the Renogy combined DC-DC/MPPT charger - and this inverter. My max inverter load will be my Microwave which is 900 Watts withe 1350 rated input power. Any advice?

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Due to a power outage yesterday I ran a 900w microwave off my 24vDC - 3000w off grid AIO (All in one) so I have some experience I can give from doing so. The watt draw was about 1400w. My LiFePO4 batteries which have a 240ah rating saw a voltage drop of about 1.1v going from 25.7v down to 24.6v during operation. The microwave ran without any issues otherwise for 3 minutes total.

Based on that I would suspect that a 2000w inverter running off 12v batteries of 200ah could possibly see enough of a voltage drop that the inverter trips out from low voltage. Especially so if they are not fully charged and there is no incoming wattage like I was getting off my PV at the time.

Edit: I am not saying it will not work for you. It would be nice if anyone that has a 12v- 2000w setup could give their experience.

LaneW said:

I don't know that I can/want to run 24 volts in what is currently set up as a 12 volt camper?

John, yes, I understand the very basics of volts (power, force), amps (amount of power) and watts (load) and that amps x volts = watts. But thats about it. Feel free to inform me, if you wish. Fundementally, I am just trying to figure out if I can safely power my MW with the inverter to warm up a meal.

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Even with 3 batteries and even with the 2200 watt inverter I cant say for sure.
Its too close to call.

I estimated 1.5x the name plate wattage.
1.5 * 1350 = 2025 watts.

Samlex estimates 2x the cooking wattage.
2 * 900 = 1800 watts

Here is some more detail that makes my eyelids droop.

If you have the microwave in your house you could measure the in-rush current with an ac clamp meter that has the in-rush measurement feature.
You will also need a line splitter.

Think About It said:

I spent days researching, reading and learning before I designed my own PV system. Granted, I have a background in electronics and electrical wiring so it may have come easier to me. My point is that you seem to want others to do the hard work for you. We are all here to help, but you have to to some of the heavy lifting. If you don't want to, then simply pay someone in the business. There are plenty of people willing to take your hard earned money.

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OK. Excuse me. I am adequately scolded. Very helpful.

Mattb4 said:

Due to a power outage yesterday I ran a 900w microwave off my 24vDC - 3000w off grid AIO (All in one) so I have some experience I can give from doing so. The watt draw was about 1400w. My LiFePO4 batteries which have a 240ah rating saw a voltage drop of about 1.1v going from 25.7v down to 24.6v during operation. The microwave ran without any issues otherwise for 3 minutes total.

Based on that I would suspect that a 2000w inverter running off 12v batteries of 200ah could possibly see enough of a voltage drop that the inverter trips out from low voltage. Especially so if they are not fully charged and there is no incoming wattage like I was getting off my PV at the time.

Edit: I am not saying it will not work for you. It would be nice if anyone that has a 12v- 2000w setup could give their experience.

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BTW, did you also check with Kill-A-Watt to see what the VA is being drawn by the MW? Thanks.

Bud Martin said:

BTW, did you also check with Kill-A-Watt to see what the VA is being drawn by the MW? Thanks.

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I grabbed my watt reading from a din rail meter on the AC output from my AIO. Do not recall the pf change though that might be of interest. I should have also done a DC amp measurement but it did not occur to me to do so. I was mostly interested in the microwave operation of start sound and operation. There was no apparent difference from being plugged into grid power versus power from inverter.

One issue is I was running it from two extension cords of 25ft for a total of 50ft. The first being a 12awg and the second 14awg. This is not ideal.

Edit: After taking my morning walk I went ahead and put the Kill-A Watt onto the microwave while heating up some instant oatmeal. This is off the normal grid supply.
Readings were 1410-1430w, 1520-1586VA and 13.16a

LaneW said:

Feel free to inform me, if you wish.

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Challenge declined.

Was not a challenge at all

John Frum said:

Instead of dumbing it down how bout we teach you so that you understand?
If you are amenable I would be glad to explain each part.

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LaneW said:

Feel free to inform me, if you wish.

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John Frum said:

Challenge declined.

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How odd.

LaneW, just to share some practical experience. The setup in my old trailer was as follows; 4 FLA GC batteries in a 12v 470Ah setup. We wanted to use the microwave, (1100w unit) but the 1000w inverter would have none of it. I replaced it with a cheap 2000w unit without issues. Everything was pretty much maxed out to run it though. #2 cable with a 150a fuse on the battery pos terminal. Little if any heating of the cabling during operation, although it was only for 2-3 minutes at a time. The Trimetric said it was pulling about 150a.

Some pompous jerks here. I was just asking for the kind of help that I would readily offer to others in my field of knowledge. (I have multiple degrees in areas aside from these). Not sure why you guys respond this way, but, cool, I’ll go elsewhere.

LaneW said:

Some pompous jerks here. I was just asking for the kind of help that I would readily offer to others in my field of knowledge. (I have multiple degrees in areas aside from these). Not sure why you guys respond this way, but, cool, I’ll go elsewhere.

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Hey LaneW - this is pretty rare, some engineer types get a bit over their skis on the social spectrum of things. It is not representative on this board for the most part.

LaneW said:

Some pompous jerks here. I was just asking for the kind of help that I would readily offer to others in my field of knowledge. (I have multiple degrees in areas aside from these). Not sure why you guys respond this way, but, cool, I’ll go elsewhere.

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I am not pompous nor do I flaunt my education to prove a point. I gave you my experience running a 900w microwave to which you made not reply.

LaneW said:

I am considering buying a 2000 watt inverter. Looking at Renogy, but I don't find that Will has reviewed this one - Hoping for feedback on my plan, which is to install 2, 100 ah SOK batteries in my truck camper with the Renogy combined DC-DC/MPPT charger - and this inverter. My max inverter load will be my Microwave which is 900 Watts withe 1350 rated input power. Any advice?

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I think this combination should be fit your need.Because there is also have the use video also have the tear down.
And it sold from amazon.

John Frum said:

Here is some more detail that makes my eyelids droop.

Marc's Technical Pages: Power Quality Symptoms and Solutions - Inrush Currents

An e-book on Power Quality, the symptoms, measurement techniques, and solutions.

www.marcspages.co.uk

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Great graphs in that link.
I've posted similar scope images I've taken on some threads.
Capacitor inrush, transformer inrush, motor loads.

The one most difficult to wrap one's mind around is transformer inrush.
But all it really means is, current through a coil of wire around an iron core makes it into a permanent magnet. Opposite polarity demagnetizes, then magnetizes with the poles reversed. While magnetization is occurring, the core resists current flowing through coil of wire, but once fully magnetized, impedance drops significantly and current shoots up. For a transformer, it is a roll of the dice what magnetization remains from last use and which polarity is being applied this time. (Have to try repeatedly to catch various size inrush spikes.)

If the building he describes has the problem of inrush blowing a main fuse when power re-applied, need to turn off all branch circuits and enable them one at a time. I've encountered that for multiple switches supplying various modules of a machine, tripping branch circuit breaker when all turned on at once.

(If you can't tell, I've been having fun playing with inductors and transformers.)