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Old 10-05-2022, 04:56 PM   #1
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Inverter for microwave, hair dryer, and Keurig

I'm going to add an inverter to our rig. We'll need it to power an 800 W microwave, Keurig machine (peak usage 1500 watts), and a small travel hair dryer, and never more than one of the above at a time. We don't need it for anything else. Would a 1500 W continuous (3000 W peak) work for this? I generally don't like to run at the maximum of a product, and my only worry would be the Keurig, as that is right at 1500 W. However, from the Keurig website it says:

"Keurig® home brewers use the most power during their initial start up. When heating for the first time after being off, peak usage is 1,500 watts. If the power is kept on, the brewer will keep the internal tank up to temperature using between 200-400 watts when heating.

While idle and not maintaining heat, the brewer will use the average electricity of a 60-watt light bulb. All Keurig® home brewers are equipped with an Energy Savings Mode Auto Off feature should you choose not to leave the brewer on. The initial heating mode when turning the power on should take about three minutes.

This information applies to the all of our coffee makers"

So with this in mind, would 1500 watts work okay for me?
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Old 10-05-2022, 05:16 PM   #2
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That initial heating takes a couple of minutes. And what if you have something else plugged in, cell phone charger, computer charger, radio, rv on standby, etc. and will you be turning your water heater off. why not go a bit larger just so you have some reserve factor? If you are planning on only powering one receptacle you might get be able to control the load. But you mention keurig, hair dryer, and microwave so it sounds like you might be powering the entire 120 volt system.
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Old 10-05-2022, 06:55 PM   #3
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The efficiency of an inverter is based on the idle or no load current, typically about 2.5 amps, plus the load current.

At 1500 watts the battery demand will approach 150 amps. A 100 aH battery will offer about 50 amps useable, thus your available battery capacity will be consumed in about 20 minutes of inverter usage. Of course, less demand from the inverter will be less demand on the battery.

I usually figure 80% for inverter efficiency and about 12.6 volts at the converter to account for cable and connector loss.

1500 x 1.2 = 1800 / 12.6 = 142.85 amps

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Old 10-05-2022, 07:04 PM   #4
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I'm lucky at my age ... the mop on top has thinned enough to towel and air dry in a few minutes


also got enough time while camping to sit and relax while brewing a cuppa on the stove


not watts about it!
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Old 10-05-2022, 07:13 PM   #5
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As pointed out above, there is a lot more to meeting your 120VAC demands than the inverter. You will need additional high capacity batteries and a way to charge them. You would likely be better off with a 2KW inverter generator to run only when you needed to run the high demand items. Remember for every 1AHr of 120VAC you need, you will need to have 10AHr of 12VDC.
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Old 10-05-2022, 07:17 PM   #6
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Your MW will probably use more than your coffee maker.
2K inverter and 200A battery might work for you!
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Old 10-05-2022, 08:01 PM   #7
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You will want a 2000W or 2400w pure-sine wave inverter, Not a modified sine wave.

While heaters, fans and some power hand tools will work fine on modified sine wave, electronics don't like it.

A couple of brand names I've been looking at is Giandel and Renogy. They are in my price range.

Giandel
https://a.co/fGOkvG6

Renogy
https://a.co/3brwVQl
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Old 10-05-2022, 08:38 PM   #8
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Quote:
Originally Posted by GravelRider View Post
"Keurig® home brewers use the most power during their initial start up. When heating for the first time after being off, peak usage is 1,500 watts. If the power is kept on, the brewer will keep the internal tank up to temperature using between 200-400 watts when heating.
Just to verify I have a Kill-o-watt meter and watched my Keurig. 1304 initial and the rest as stated. Have you verified that 1500?


Agree with the other guys a 2000 with enough battery and correct cables and fuses/breakers.
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Old 10-05-2022, 08:50 PM   #9
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The batteries also need to be able to discharge at a rate that your inverter will be asking for based on what it's trying to supply.
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Old 10-05-2022, 10:37 PM   #10
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Just to verify I have a Kill-o-watt meter and watched my Keurig. 1304 initial and the rest as stated. Have you verified that 1500?


Agree with the other guys a 2000 with enough battery and correct cables and fuses/breakers.
I don't drink coffee but my wife does. I make it 95% of the time. Fortunately she didn't fall for any of those fancy k-cups or kerigs,.... but then Starbucks aint cheap.

Anyway, when boondocking I think you need to just skip the Kerig and boil water on the stove the old fashion way. Then you might be able to get away with a smaller 1000w invertor and smaller wires and battery.

Just a thought.

Jim M.
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Old 10-05-2022, 10:47 PM   #11
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We make tea by boiling a kettle of water on the gas cooktop and properly steeping the tea. Coffee is made likewise using fresh ground beans in a percolator on the gas cooktop.

Otherwise, we find the microwave and Keurig brewed stuff slightly worse than the water from boiled socks.

Bob
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Old 10-06-2022, 06:32 AM   #12
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Quote:
Originally Posted by jimmarako View Post
I don't drink coffee but my wife does. I make it 95% of the time. Fortunately she didn't fall for any of those fancy k-cups or kerigs,.... but then Starbucks aint cheap.

Anyway, when boondocking I think you need to just skip the Kerig and boil water on the stove the old fashion way. Then you might be able to get away with a smaller 1000w invertor and smaller wires and battery.

Just a thought.

Jim M.
And this is helping the OP figure the size inverter he needs to live the way he wants to how?
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Old 10-06-2022, 06:37 AM   #13
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I guess I should have clarified a few things.

I currently have a 3500 watt inverter generator that I would prefer not use, unless I need AC. As it is now, we can boondock for days without using it (if it's not entirely too hot), if it weren't for using the Keurig for a few minutes in the morning, and using the microwave to warm foods once in awhile. My wife will dry her hair (I've kept mine buzzed for the last 20+ years) once in awhile, but honestly this is the least pressing of our uses for AC power.

We do have a Bialetti coffee maker that makes excellent coffee... But it's a slow process that we don't care to do every morning. The times when we'd really love to have the inverter is when we're spending the night at a rest area or Walmart or such, and we want to make a couple of coffees, heat up some breakfast for the kids, and hit the road early in the morning, which we frequently do when making use of a long weekend. Using the generator for this situation is less than ideal, and time consuming.

Those are literally the only three things we use that are AC. We have DC plugs throughout our rig that we use for device charging, running DC fans, and even our television is a DC powered one. There is no worry about accidentally having several AC devices running at the same time.

We currently have a 430 Ah LA battery bank with 800 watts of solar. The only thing we're missing is an inverter for larger AC items. I do have a small 300 watt plug-in inverter that we have for just in case for smaller AC items.
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Old 10-06-2022, 06:50 AM   #14
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Here's a curiosity. Do you want to install this inverter so it powers existing outlets? Have you considered an inverter with built-in transfer switch? Do you know how this would work?
Here's a few at DonRowe.
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Old 10-06-2022, 08:17 AM   #15
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Sounds like you've got a stout enough LA battery bank.


Your question is one that I've thought a lot about in the past for when I upgrade our DC power system when we're able to do more boondocking.


Were it me, I'd go with a 2000 watt pure sine wave inverter. That will give you some headroom so that you're not overly stressing the electronics inside the inverter. I look at max ratings on electronics just like weight ratings on tires... Yeah, it should do it, but you really shouldn't. The prices on PSW inverters seem to be coming down a bit.



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Old 10-06-2022, 08:44 AM   #16
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Inverter should only pull from your battery the actual load you are trying to power up PLUS some overhead.
It does not invert the full stated amount (1500W) and you have to use it or loose it!
with that big battery bank you can use the larger 1500 - 3000 W inverters

BUT ....
when you start to use the larger inverters you need to

12v supply wires from the battery to the inverter need to be the correct gauge.
Measure the distance from battery to inverter and back to the battery that is the length of the circuit.

Your inverter manufacturer will tell you what gauge you need based on the circuit length

try and keep inverter as close to the battery as possible
depending on inverter size and distance from battery the cable can add significant cost and installation effort.

have a 12v fuse close to the battery positive terminal


an isolation switch so you can EASILY disconnect the inverter while not in use. Other wise the inverter will just add to your existing parasitic load for no good reason

Isolation switch needs to be in a spot you can easily access from INSIDE
you don't want to have to run outside in the cold rain first thing in the AM to turn on the coffee maker!

Then you have to determine if you power the existing outlets with the inverter
OR use a extension cord running through the trailer to a small power strip .
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Old 10-06-2022, 11:24 AM   #17
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Quote:
Originally Posted by Zoso1971 View Post
And this is helping the OP figure the size inverter he needs to live the way he wants to how?
Over the several years I've been here this exact question has come up multiple times: "I need an invertor to make coffee, cook,.....". Most of these people have one or two dual purpose lead acid batteries and the factory 100W solar panel. Once they figure out that they will need to spend $2K+ to make that cup of coffee the "just boil water on the stove" makes a whole lot of sense.

After I posted the OP let on that he has a fairly large solar array and battery bank already. So his costs are much much lower for an invertor and a couple feet of thick wire. He has gotten several answers to that.

So yeah, sometimes giving and answer that isn't exactly what the OP was asking is the best answer.

Jim M.
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Old 10-06-2022, 02:16 PM   #18
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Quote:
Originally Posted by GravelRider View Post
I'm going to add an inverter to our rig. We'll need it to power an 800 W microwave, Keurig machine (peak usage 1500 watts), and a small travel hair dryer, and never more than one of the above at a time. We don't need it for anything else. Would a 1500 W continuous (3000 W peak) work for this? I generally don't like to run at the maximum of a product, and my only worry would be the Keurig, as that is right at 1500 W. However, from the Keurig website it says:

"Keurig® home brewers use the most power during their initial start up. When heating for the first time after being off, peak usage is 1,500 watts. If the power is kept on, the brewer will keep the internal tank up to temperature using between 200-400 watts when heating.

While idle and not maintaining heat, the brewer will use the average electricity of a 60-watt light bulb. All Keurig® home brewers are equipped with an Energy Savings Mode Auto Off feature should you choose not to leave the brewer on. The initial heating mode when turning the power on should take about three minutes.

This information applies to the all of our coffee makers"

So with this in mind, would 1500 watts work okay for me?
To answer your question straight up, I suggest a minimum of a 2500-watt rated pure sine wave inverter. One never wants to plan to operate anything at max-rated values.

Bob
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Old 10-06-2022, 04:10 PM   #19
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Originally Posted by Zoso1971 View Post
Here's a curiosity. Do you want to install this inverter so it powers existing outlets? Have you considered an inverter with built-in transfer switch? Do you know how this would work?
Here's a few at DonRowe.
At this time, I'm not planning to do the automatic transfer switch. We're planning to get a bigger camper in the next year or two, and a couple of hundred bucks for an upgrade for the season or two more camping with this rig is fine, but I'll save the more expensive one for our next rig... When I get a bigger solar setup and larger Li battery bank too.
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Old 10-06-2022, 04:20 PM   #20
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Originally Posted by BriaBeck View Post
Sounds like you've got a stout enough LA battery bank.


Your question is one that I've thought a lot about in the past for when I upgrade our DC power system when we're able to do more boondocking.


Were it me, I'd go with a 2000 watt pure sine wave inverter. That will give you some headroom so that you're not overly stressing the electronics inside the inverter. I look at max ratings on electronics just like weight ratings on tires... Yeah, it should do it, but you really shouldn't. The prices on PSW inverters seem to be coming down a bit.



Quote:
Originally Posted by Aussieguy View Post
Inverter should only pull from your battery the actual load you are trying to power up PLUS some overhead.
It does not invert the full stated amount (1500W) and you have to use it or loose it!
with that big battery bank you can use the larger 1500 - 3000 W inverters

BUT ....
when you start to use the larger inverters you need to

12v supply wires from the battery to the inverter need to be the correct gauge.
Measure the distance from battery to inverter and back to the battery that is the length of the circuit.

Your inverter manufacturer will tell you what gauge you need based on the circuit length

try and keep inverter as close to the battery as possible
depending on inverter size and distance from battery the cable can add significant cost and installation effort.

have a 12v fuse close to the battery positive terminal


an isolation switch so you can EASILY disconnect the inverter while not in use. Other wise the inverter will just add to your existing parasitic load for no good reason

Isolation switch needs to be in a spot you can easily access from INSIDE
you don't want to have to run outside in the cold rain first thing in the AM to turn on the coffee maker!

Then you have to determine if you power the existing outlets with the inverter
OR use a extension cord running through the trailer to a small power strip .
It sounds like I should buy at least a 2000 watt inverter. I'll definitely be using thick gauge wire appropriate for the size inverter and length of run. I'm hoping to keep the run under 5' total. Though, if I have an isolation switch inside, that will increase the total length to more like 8-10 feet. Though, if I do need that long of a run, I'll definitely get the proper gauge based on ampacity charts/voltage drop calculators.

What I was planning to do was to put in 3 new outlets that would only be on the inverter. Due to tons of home projects I've done over the years, I've already got plenty of wire and outlets at home, so this wouldn't add any additional cost to the project.
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