Inverter help

[jimi1952]

Hello, we have a 2012 212qbw that is set up for solar. 320 watts with two 100 amp Battle Born lithium batteries. We do mostly boondocking, but now would like to install an inverter so we could run our microwave if needed. The microwave is a North Pointe that I believe is 1250 watt. My question is what size inverter is needed and how to connect it to our current system? I did the install of our solar system so I'm confident that I can do the inverter with some technical assistance. Thanks for any and all replies.

[us71na]

I don't think you can do what you want. Inverters are not 100% efficient converting 12 volts DC to 120 Volts Ac. A microwave typically uses 1,000 watts of power. Assuming you are on solar at full capacity and both batteries are fully charged. A 100 amp battery only holds a total 1200 watts of power of which half is probably useable. So you probably have about 1500 watts of power for a few minutes until the batteries go flat.

[JimD]

Agreed that an inverter trying to run a microwave is not a good idea. If your microwave is 1200 watts that would equate to pulling 100 amps from your batteries. That is not taking into account any losses, just a quick formula. You basically take the required input current of the 120 volt device, in this case about 10+ amps, and times it by 10.

A much better way around this is to purchase a little inverter/generator. I have 2 12 volt batteries plus 200 watts of solar and when I use my inverter to power a TV it still sucks the batteries down after awhile.

I purchased a 2200 watt inverter/generator and consider it the best purchase I made for power. It will charge my batteries, run the microwave by itself, run the TV, etc. If just charging the batteries plus running the TV it will go all day on 1 gallon of gas.

[bababooey]

Originally Posted by JimD

Agreed that an inverter trying to run a microwave is not a good idea. If your microwave is 1200 watts that would equate to pulling 100 amps from your batteries. That is not taking into account any losses, just a quick formula. You basically take the required input current of the 120 volt device, in this case about 10+ amps, and times it by 10.



A much better way around this is to purchase a little inverter/generator. I have 2 12 volt batteries plus 200 watts of solar and when I use my inverter to power a TV it still sucks the batteries down after awhile.



I purchased a 2200 watt inverter/generator and consider it the best purchase I made for power. It will charge my batteries, run the microwave by itself, run the TV, etc. If just charging the batteries plus running the TV it will go all day on 1 gallon of gas.

1200 watts/120v = 10 amps, not 100 amps, no?

[JimD]

Originally Posted by bababooey

1200 watts/120v = 10 amps, not 100 amps, no?

Yep you are pulling 10 amps at 120 volts. But to get those 10 amps at 120 volts from an inverter would equate to 100 amps being drawn from the batteries.

10 amps times 120 volts equals 1200 watts.
100 amps times 12 volts equals 1200 watts.

You don't get something for nothing. The inverter is basically a step up transformer. Ideally to get 1200 watts out you need to get 1200 watts in. This is in its simplest terms.

[bababooey]

Yes, you are correct.. Start the generator.

[Allen_C]

The OP stated he has two 100ah Battle Borns, which are LiFePo4 chemistry. They should allow 100a draw down to cover what the inverter will need to run the microwave. The key is to get an inverter that is a pure done wave since microwaves don't like modified and rated for a continuous 1500w to give you a little extra capacity.

How to get the microwave powered by the inverter will require you to choose to simply plug the appliance into the 120v outlet on the inverter or to wire the inverter to your breaker panel that feeds all the 120v outlets.

[jimi1952]

I want to thank everyone for the replies. I wasn't sure about the technical issues, which is why I posted in the forum.

[Seann45]

I disagree with most of the comments.. I have a solar system with a 2000 watt full house inverter and routinely run my microwave. Yes I have a bigger battery bank than you do but it is flooded L/A.. worst comes to worst add a third battery

[WeRJuliian]

Have you considered a 12V microwave?
Very popular with truckers, as I recall

This, for example

[jimi1952]

Talked with a rep. from Battle Born batteries and according to him we will be fine running the microwave on a 2000 watt inverter. We have 2400 watts stored power in our batteries and could run the microwave for 5 minutes and use a small fraction of our power. Thanks to everyone that replied.

[us71na]

Originally Posted by jimi1952

Talked with a rep. from Battle Born batteries and according to him we will be fine running the microwave on a 2000 watt inverter. We have 2400 watts stored power in our batteries and could run the microwave for 5 minutes and use a small fraction of our power. Thanks to everyone that replied.

Let us know how that works out......

[Jay2504]

jimi1952, here is another option for you. Most microwave ovens have a power setting. If you put the typical microwave at 50% power it uses the same input wattage, but cycles off and on, compared to 100% on at 100% power. In the case of our unit it’s about 1400 watts. But if you buy a Panasonic Inverter Microwave, when it is at say 50% power setting the input power stays continuously on, but the wattage drops to like 650 or so watts. What this does is let you use a smaller inverter, smaller,wiring , and in the case of us lead-acid guys,it’s much easer on the battery bank. The total power is the same but it’s less at one time. After all who cares if the hot dog takes 1 minute instead of 30 seconds? This is a upcoming project for our 24RBS. The new microwave is not expensive and they make one that fits exactly like the original in my unit. I will post up when I do it, but realistically it will be a few months. Jay

[jimi1952]

After talking it over with my wife, we decided not to get an inverter after all. We have a Yeti Goal Zero that can run the microwave in a pinch and since we do 90% dry camping it will meet our needs.