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Old 19-07-2012, 18:37   #1
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Will refrigerator run on inverter ?

I got a 1990 Carver Santego 3467 several months ago. Can anyone tell me what I can run on the inverter? What do I need to start the generator to operate? I'm fairly sure I need the generator for the A/C, range, oven and microwave. How long can I use the inverter without charging the batteries? Any instruction appreciated.
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Old 19-07-2012, 18:41   #2
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Re: Will refrigerator run on inverter ?

How big is the fridge? how big is the inverter? how big is the batt bank?

I ran my fridge for 7 years off an inverter!
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Old 19-07-2012, 18:47   #3
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Re: Will refrigerator run on inverter ?

CH, I would suggest you give yourself the time to do some studying on inverters and your electrical system. Too many unknowns and variables to be able to answer your questions. Although not marine related, there is some good basic info here, Inverter FAQ - DonRowe.com - Frequently Asked Questions about Power Inverters. And another here, http://www.boatus.com/boattech/articles/inverters.asp . Chuck
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Old 19-07-2012, 18:56   #4
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Re: Will refrigerator run on inverter ?

I'll try to answer beginning with your last question. How long can you use your inverter without recharging the batteries??? Well of course, until the batteries are dead.

But seriously, if you're running a fridge, BE PREPARED!!! What you need to do is know the operating current....I presume on 12vdc and the duty cycle. For instance, if your fridge draws about 6 amperes @ 12 vdc, you next need to know the duty cycle which is the ratio of on time to off time. 50% on, 50% off is a duty cycle of .5 so the total drain on the battery is 6 amperes times 0.5 or 3 amperes. Now this can get a little complicated. Battery discharge hours depends not only on charge but at the rate of discharge. A 100 ampere hour battery may provide 1 ampere for 100 hours, at 20 amperes it may only provide 3 or 4 hours. You need to check your battery's performance curve.

I use a 1 kilowatt Xantrex pure sine wave inverter for my 8.3cu ft Summit fridge that has a self defrost mode and an interior light. The reason for the high wattage capability is to be able to handle the inrush current when the fridge starts along with the self defrost. Be careful using an inverter. Many motors do not like pseudo sine waves. Personally I would try a cheapo from Harbor Freight something for less than $100 in the 1 kilowatt range. If it works your fine, if it does not, return it.

Foggy

EDIT: WATERWAYGUY's post above mentioned the inverters in his URL pointer may not be marine rated. I MUST point out that if your place an inverter or for that matter anything in a bilge, it must be marine rated. My inverters are NOT in my bilge. Give that some though.
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Old 19-07-2012, 18:59   #5
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Re: Will refrigerator run on inverter ?

The fridge is twice the size of a "college fridge" with a small seperate freezer on top. I have no idea on the inverter - it came with the cruiser. I am novice (but pro compared to the lady who got it in divorce and sold it to me). I have a lot to learn, quickly.
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Old 19-07-2012, 19:16   #6
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Re: Will refrigerator run on inverter ?

genset. fridges dont like invertors. they LOVE gensets.
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Old 19-07-2012, 20:08   #7
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Re: Will refrigerator run on inverter ?

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genset. fridges dont like invertors. they LOVE gensets.
Come on now, what do you mean fridges do not like inverters? I do agree that SOME fridges do not like SOME inverters. A good properly sized true sine wave inverter will run most AC motors flawlessly.

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Old 19-07-2012, 20:17   #8
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Re: Will refrigerator run on inverter ?

can run fridge 7 yrs off invertor--but......depend on fridge and depends on invertor and depends on ......
we found a small apartment sized or dorm sized fridge doesnt like invertors for more than 3 months before dying. needs special invertor. is so much fun having cold foods become garbage because fridge isnt liking invertor.
research your options and see what YOUR fridge and YOUR invertor are able to do together.
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Old 19-07-2012, 20:39   #9
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Re: Will refrigerator run on inverter ?

OK Zeehag, I will go along with your last post which by the way is essentially what I posted.

The problem with the so called pseudo sine wave inverters, the cheapies can be blamed on the harmonics the waveform contains. They are obvious if one does a Fourier analysis of the wave shape.

But again, I am not in full agreement with the Fourier analysis approach. I believe a lot has to do with the time domain analysis of the waveform. By that I mean the volt time integral of the upper and lower waveforms are not EXACTLY equal that allows the operating point on the B-H curve to walk up/down the curve putting the core into saturation.

But ignore all that crap above. If you have a decent sine wave inverter, you should be just fine PROVIDING the inverter is capable of swallowing starting surges.

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Old 19-07-2012, 20:46   #10
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Re: Will refrigerator run on inverter ?

Have been running a household-type whirlpool 15 cf refrigerator freezer off a Heart 3kw Freedom (square wave) inverter for the last 8 years without any problems. House battery bank is comprised of six group 31 AGMs (now 5 yrs old). Other AC loads include Intellian sat TV as well as the usual laptop devices. Typically recharge batteries when not underway about every 30 hours pending DC loads (fans, LED lighting, etc.). Raritan ice maker decreases interval between charging by 6 to 8 hours. Don't let your battery voltage drop below 12V. Will probably change to true sine wave inverter when this one fails.
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Old 19-07-2012, 20:56   #11
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Re: Will refrigerator run on inverter ?

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Originally Posted by emcmia View Post
Have been running a household-type whirlpool 15 cf refrigerator freezer off a Heart 3kw Freedom (square wave) inverter for the last 8 years without any problems. House battery bank is comprised of six group 31 AGMs (now 5 yrs old). Other AC loads include Intellian sat TV as well as the usual laptop devices. Typically recharge batteries when not underway about every 30 hours pending DC loads (fans, LED lighting, etc.). Raritan ice maker decreases interval between charging by 6 to 8 hours. Don't let your battery voltage drop below 12V. Will probably change to true sine wave inverter when this one fails.
I had to avoid using my kilowatt inverter last week, tired battery problem that I addressed in another thread here in the forum. Si I resorted to my 24vdc system that energizes an old Heart/Xantrex kilowatt pseudo sinewave inverter. The fridge ran silently without trouble. Our microwave though, growled. I think much of the newer stuff such as fridges are designed to operate on waveforms other than true sine waves.
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Old 19-07-2012, 20:58   #12
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Re: Will refrigerator run on inverter ?

Hi Carver Heaven,

From your description I am guessing you have a home type refrigerator. Does it have a regular plug like your refrigerator at home? That means it runs on AC electricity which is what you have at home. Boats and cars run most of their stuff on DC electricity, what you get out of the battery.

An inverter will change the battery power to AC house type power but it takes roughly ten times more amps from your 12V battery to make the same number of amps at 125V AC house power. So if your refrigeration draws 2-3 amps that isn't much but it is at 125V. That means you will draw roughly 20-30 amps from the battery to power the refrigerator. Unless you have several very large batteries this will completely run down your batteries in a few hours.

Now for the inverter. There are two common types, pure sine wave and not. The not sine waves are much cheaper but many motors and electronics will not run well if at all. Next you have to look at the power rating of the inverter. It has to be big enough to run the refrigerator. More or less like you need an engine with enough horse power to power your car.

Also, even if you have enough batteries and the correct inverter to run the refrigerator you also have to have some way to recharge the batteries. If you are plugged into power at a dock you can do this with a battery charger.

So, you need to get a bunch of details to figure out how this will or will not work.
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Old 19-07-2012, 21:08   #13
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Re: Will refrigerator run on inverter ?

My refrigerator is running on the inverter now. The frige pulls 1.3 amps (measured) at 120V, which is about 15 amps DC thru an inverter. Duty cycle for me with cabin in the 80's is about 0.15 (~2.5 minutes in 14 minutes) so about 2.5 amps per hour. I've a 3.5 CF dorm type with a 700watt modified sine wave (cheap WM) inverter. Had it over five year, though first few years were at the dock, so no inverter.

Works for me anyway.. YMMV
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Old 15-02-2015, 09:55   #14
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Re: Will refrigerator run on inverter ?

Sailorchic...Inverter size to run dorm fridge?
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Old 15-02-2015, 10:50   #15
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Re: Will refrigerator run on inverter ?

It's the starting amps that's the killer. The compressor motor has to start against a load, which takes a surge of amps that maybe your inverter/batteries can't meet, causing an under voltage condition, and motor heating. The motor tries to pull even more amperage, which makes it get even hotter. A few thousand cycles of this, and it dies.
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