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Old 05-03-2015, 09:46   #1
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Choosing appliances for an Inverter

Thought I would start a thread on this subject.

I found from experience that when you install an inverter you need to consider how you want to use it. If you want to be on all the time and powering your outlets steady at a cost of amp hours added to your daily usage. Pure Sine Wave Inverters take between 2 amps and 7 amps to do there job . This is what it takes the inverter to change 12v DC to 120V ac @60hz . This is without any load . So 24 hours of being "on" could cost you between 48 and 160 amp hours a day .

You really want to keep these things in "Sleep mode" !! In this mode most units send out a pulse or a low level ac signal looking for a load to turn itself on . We are talking milliamp's.

This is the tricky part most appliances have electronic circuitry thats needs a constant ac source just to be able to turn itself on . I discovered this when I tried to use my inverter to power my domestic water pump . I use a Headhunter Mach 5 pump , which is great but it is controlled by an electronic pressure switch . So if I leave the inverter in the full on mode it works , if I let the inverter sleep the pump will not wake it up and not work.
To solve this I moved to a mechanical pressure switch that will wake the inverter as the pressure in the system drops and turns it off when it has reached the desired pressure.
I also had to buy a microwave that had mechanical controls , or dials / knobs.
So it works like a switch, on and off , no clock , no electronic controls .

This allows the inverter to be in sleep mode 24hrs a day using milliamp's and only powering up when I have a big job for it .

Any one have similar experiences ?

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Old 05-03-2015, 12:56   #2
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Re: Choosing appliances for an Inverter

Well yes, I selected a microwave oven with no clock (it does have electronic controls, though). I use the remote inverter switch to turn it on when needed and if I forget to turn it off it sleeps and draws a fraction of an amp.


My potable water pump is 12 volt so the inverter is not needed. So is the TV/DVD. It's simpler that way.
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Old 05-03-2015, 13:03   #3
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Re: Choosing appliances for an Inverter

Yes I agree , keeping as much as you can in the 12v realm is always a plus

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Old 05-03-2015, 17:30   #4
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Re: Choosing appliances for an Inverter

Explains why my only serious 120v appliance is my mini shop vac. The admiral loves it.
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Old 06-03-2015, 04:31   #5
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Re: Choosing appliances for an Inverter

I have a Xantrex PSW 2000 inverter, that I leave on all of the time. It draws 1/2 an amp, with no load. It has no idle mode.

It works everything, right down to a phone charger.

The convenience of power, throughout the boat, is worth the 12 AH a day, since we are fulltimers, with a residential refrigerator.

When inverter shopping, you just need to check the specs.


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Old 06-03-2015, 08:04   #6
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Re: Choosing appliances for an Inverter

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Originally Posted by twinboat View Post
I have a Xantrex PSW 2000 inverter, that I leave on all of the time. It draws 1/2 an amp, with no load. It has no idle mode.

It works everything, right down to a phone charger.

The convenience of power, throughout the boat, is worth the 12 AH a day, since we are fulltimers, with a residential refrigerator.

When inverter shopping, you just need to check the specs.


Enjoy

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Wish they could design a low frequency inverter that wouldn't take so much power when inverterting . My Vanner Brutus weighs 65 pounds but has no decipherable RF noise . I know some HF inverters are very RF noisy bad for my SSB

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Old 06-03-2015, 08:14   #7
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Re: Choosing appliances for an Inverter

Found this write up comparing the two technologies .

Introduction to Mobile Power Inverters | Dimensions

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Old 06-03-2015, 09:44   #8
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Re: Choosing appliances for an Inverter

I have a big Blue Seas on/off switch near the inverter. Easy enough to turn it on when I need it.
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Old 06-03-2015, 13:59   #9
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Re: Choosing appliances for an Inverter

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Originally Posted by onestepcsy37 View Post
I have a big Blue Seas on/off switch near the inverter. Easy enough to turn it on when I need it.
It's certainly a good idea to be able to turn the inverter off when needed. Often though, a traditional switch in the DC power lead will extend the wiring run past the recommended length. Many modern inverters come with a remote switch or offer one as an accessory.

Mine also indicates the battery voltage (when the inverter is on) and the wattage of the load. And the reason if the inverter shuts itself off.
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Old 06-03-2015, 21:13   #10
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Re: Choosing appliances for an Inverter

Not sure where you are getting your figures from. Most inverters, have a no load draw from 0.5 to 2 A. This isn't sleep mode, which is even less. Using 120Vac appliances where there are adequate 12 Vdc appliances (such as for domestic water pumps) is kinda bad practice, as the inverter is only 90$ efficient at best, so your are losing energy in the conversion.


You are correct that phantom loads will cost. Consider the Amp draw at 120V and multiply by 14 (including a fudge for inverter eff. to get the corresponding Amp draw at 12V.


But before worrying about that, you should be shutting off the GFCIs when not in use, as they draw power too, so whether the appliance connected represents a phantom load is moot.


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Old 06-03-2015, 21:24   #11
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Re: Choosing appliances for an Inverter

I'm in favor of appliances not using electricity. My main electrical draw is for the refrigerator (yeah there is the toilet, VHF radio, fish finder, lighting, and radar/plotter too). I use AC outlets for charging smart/iPhone as well as AC for the air compressor powering the horn, from an inverter. Stove is gas. Any appliance creating heat consumes a lot of energy.
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Old 06-03-2015, 21:44   #12
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Re: Choosing appliances for an Inverter

Quote:
Originally Posted by typhoon View Post
Thought I would start a thread on this subject.

I found from experience that when you install an inverter you need to consider how you want to use it. If you want to be on all the time and powering your outlets steady at a cost of amp hours added to your daily usage. Pure Sine Wave Inverters take between 2 amps and 7 amps to do there job . This is what it takes the inverter to change 12v DC to 120V ac @60hz . This is without any load . So 24 hours of being "on" could cost you between 48 and 160 amp hours a day .
2 to 7 amps no load seems like an awful lot. My 1500 Watt inverter uses around 1/2 an amp no load.

If it used 2 amps I'd be unhappy. 7 amps I'd be doing something about it.
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Old 07-03-2015, 06:18   #13
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Re: Choosing appliances for an Inverter

Small Hf inverters have very low draw on standby as do Lf inverters . I have two Lf inverters on board , a xantrex SW2000 and a Vanner Brutus 2400 w . The Xantrex uses 3.5 amps while inverting and the Vanner 7 amps . I have measured both of them myself . On search or sleep mode they would both draw aound 1/2 an amp . Both are pure sine low frequency inverters . Other manufacturers have similar numbers but may not be stated . I actually called Dimensions inverters to find out there amperage on invert mode and it was 4 amps . The key to my plan is to have the inveter on , but always in sleep mode and ready to use . To do this I have to choose appliances with out any electronic switching as these would keep the inverter full on just to power a small clock in a microwave or a similar thing. I really don't want to constantly turn the inverter on and off or always unplug the microwave or water pump . My goal is to make the system similar to a home experience



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Old 07-03-2015, 15:32   #14
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Re: Choosing appliances for an Inverter

You could put a switch in the microwave cord. When you need it, switch it on.

I used a spring wound timer, on my microwave cord. Wind it up, use the digital buttons and blast the food. It shuts off in a few minutes.

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Old 08-03-2015, 12:47   #15
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Re: Choosing appliances for an Inverter

I debate this issue in my head all the time. The overhead and added complexity of an inverter just seems like a poor 'solution'.
Burning up amps for convenience sake.
Having everything run directly on DC battery power is just so much simpler and more efficient.

Yet it seems the reality is there are things you can't run on DC, or at least the effort to convert them is too much.
I have been working on an efficient 12v microwave, the bigger the power draw, the more savings there are to be had.

But then I have a coffee bean grinder that is AC.

I keep going around with this. If the inverter is going to be needed, why not making EVERYTHING run on AC ? It is my impression that AC appliances are not designed to be efficient. The microwave is a perfect example, the products assume 'free' electricity and don't worry about wasting large amounts of it to save a few dollars.
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