Curious Question

[tahoe1840]

A group of friends and I were talking all things RV and struck upon this curiosity about using an invertor while boondocking or dry camping. When there is no shore power or generator can one temporarily plug the shore power cable of their RV into an adequately sized invertor to run the microwave for a minute or two? Will this cause a problem for the convertor? Anyone try this?

[tomkatb]

Sure

The bigger the battery bank and inverter you can run anything!

2000/4000 peakwatt inverter properly wired should run a microwave. Two batteries discharged in about an hour.

[Paulie1138]

Yes you can....BUT!!!!!!! You will need a large enough inverter, a battery bank big enough to handle the discharge rate. That said, assume your microwave is 1,000 watts. You will need a minimum discharge rate of around 150 amps while it is running. (Inverters are not 100% efficient) Most single battery banks will be destroyed after several minutes at this rate! Sometimes with disastrous results!

[tomkatb]

Forgot to mention disconnecting the converter. Flip the breaker.

[ependydad]

That's actually how we run our camper when boondocking. I only have a 1,000W inverter so no microwave, Instant Pot, or A/C. Even the A/C fan is iffy depending on what else is running at the moment (it worked great for 10-15 minutes and then tripped the inverter's overload- my guess is our mini-fridge's compressor kicked on).

Inside the camper, I turn off all of the breakers except for the main house one. Then I'll manage the load by controlling which breakers I turn on. I have 2 breakers that control a vast majority of outlets in the rig.

I have a 50amp to 15amp adapter that plugs right into the camper's shore power inlet. Then I have a 50' x 10 or 12 gauge heavy duty extension cord that I run to the GFCI on the inverter.

Battery-wise, I have four 100amp-hour lithium drop-in batteries from Battle Born. The way they have their batteries setup is that you're able to use all 100amps, so it's like having close to a 800amp lead/AGM battery bank (where you shouldn't go under 50% state of charge).

If I had a bigger inverter, I wouldn't mind running the applicances that I can't now.

[timfromma]

It will work in theory but I would advise against it. Microwaves use ALOT of power and will likely drain your batteries VERY rapidly. Use the propane oven and stove to heat things up while boondocking.

[ependydad]

Originally Posted by tomkatb

Forgot to mention disconnecting the converter. Flip the breaker.

This is an absolute must. Otherwise, you'll send your batteries into a quick death spiral by trying to self-charge them via the inverter.

[herbike]

I had a 1500 watt inverter in the truck I was driving for a living. I found that with 4 12v batteries it wouldn't run the microwave efficiently without the motor running to add more charge to the batteries. Best example is popping microwave popcorn, it wouldn't pop all the corn on battery power alone, with the motor running it worked normally. I only had 3 ft #4 cables from the batteries to the inverter.

[Arctic Wolf]

#4 is too small for the load, you get voltage drop which increases the current draw which drops the voltage...

[bikendan]

It's so much easier to just get a 2000w inverter generator.
You can run the microwave and recharge the batteries.

[ependydad]

Originally Posted by bikendan

It's so much easier to just get a 2000w inverter generator.
You can run the microwave and recharge the batteries.

If you’re already investing in the battery bank, I wouldn’t say “easier”. Unless you have a remote start for the generator, you have to go outside- fire it up, microwave your stuff, go back outside and shut it down.

It’s a whole lot “easier” to just start the microwave.

[Chaplain Kent]

Boon docking/ Microwave is an oxymoron.

[dbledan]

Originally Posted by ependydad

If you’re already investing in the battery bank, I wouldn’t say “easier”. Unless you have a remote start for the generator, you have to go outside- fire it up, microwave your stuff, go back outside and shut it down.

It’s a whole lot “easier” to just start the microwave.

You are right but DW demands AC even when 70 outside....I have to do that anyway :-)

[pjnlorrie]

With due respect to "What True Boondocking Is" here are my observations;
Rigs big enough to have battery banks large enough for running a microwave typically have an inverter big enough to cover this,and an on board genny so its a non-issue.
For smaller rigs, like a TT with 1 or 2 batteries, the microwave is a huge draw. I considered such an upgrade, but the microwave would kill my batteries in minutes. I installed a 300 watt inverter with a dedicated outlet. It runs the television, charges gadgets that need 120v, and laptops. For cooking, propane is your friend. If we just must have the microwave, or AC, like Bikendan said-it is generator time.

[RangeMaggotBob]

Originally Posted by Arctic Wolf

#4 is too small for the load, you get voltage drop which increases the current draw which drops the voltage...

Are you sure about that? #4 is pretty hefty wire.

[cavie]

Originally Posted by RangeMaggotBob

Are you sure about that? #4 is pretty hefty wire.

Good for 100 amps AC in most cases.

[timfromma]

If you are going to attempt this, keep your inverter as close to the batteries as possible to minimize DC voltage drop across the wire.

[johnbryanpeters]

I solved this problem by removing the microwave oven from my R-Pod, and gained a lot of storage space as a side benefit.

[dustman_stx]

Originally Posted by RangeMaggotBob

Are you sure about that? #4 is pretty hefty wire.

If you're running true 4 AWG OFC wire, then it should handle 150 amps or better if it's only a 4-7ft run. You want to locate the inverter as close to the battery bank as possible since it takes larger wire to carry lower voltage for a given amperage.

[Paulie1138]

Problem with AC vs. DC, is best summed up...Line loss. All wiring has resistance to electron flow per foot.


With AC circuits, you will have about the same line loss in voltage per foot as a DC circuit. However, with AC, you are usually talking 120 volts. If you get the spec's on wire, you can calculate line loss in volts per given distance. So, if you are talking a loss of 4 volts at say, 5 feet under load (in amps), then your loss is very minimal at 120volts, as it drops from 120v to 116v.


Drop that 4 volt loss to 12 volts dc, then you are talking significant voltage drop. 12v -4v =8v. Your device will draw even more current trying to make up for the voltage drop, exacerbating the problem.


To figure out what wire size (gauge) you need, you really need to include the voltage drop of the distance you are going when setting up DC systems. These can be found here: Voltage Drop Calculator