Invertor size for a refrigerator

Knowing what the locked rotor draw is where you should start. I made the mistake of matching an inverter to a fridge where the inverter should have handled the load but didn't. I replaced that inverter with a larger one and haven't had any issues since.
The Tripp Lite inverters that are built for motor startup have a good rep but prices are getting closer with the newer sine wave inverters. I am using a Xantrex Prowatt inverter and think it's a fairly well built device.

Gdetrailer wrote:


What a bunch of bovine droppings.....

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No need to be so sub-tile. That 1250 seems alright. I like my MSW Vector 2000w, but they don't make them anymore. It runs the MW ok. It runs any kind of motor ok. Lawn trimmer, air compressor, drill. Can't see why it would not run a fridge.

There is the usual list of things that don't run on MSW, but these are fussy things that have SCRs or whatever. Laser printers, etc. I never saw a fridge on any such list.
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My home fridge has a compressor driven by three phase electric. GE Profile(or is it Monogram?), cabinet depth, built in. I believe the three phase is created electronically by an inverter of sort. I wanted to add a timer to stop the compressor during peak TOU electric rates. After reviewing the set up I let it alone. I would not trust it to MSW but then it would be rare in an RV.

rkentzel wrote:
There a few refer out there now that are three phase run from inverter boards for it. Plus it may have two to three boards running different functions. I would only want a psw inverter for mine. I speak from being authorized service for the majors now retired. I have seen people who go out and spend all kinds of money tearing out there rv frig and replacing it with 2500-3000 dolar refer and cheap out and put some cheap junk modified sine wave inverter in makes me cringe.

Most all the boards are under in the back or on the back panel not a normal installation so you would have to unistall it for a tech to repair it. If its just static coil design just stick it in leave so room for air circulation and put in which one you want. Ya and I know some of you say you run MSW on you big dollar fridge but you pay for that at some point.

:R

What a bunch of bovine droppings.

Perhaps you should post a few model numbers of those supposed "three phase" home fridges?

I would only expect that type of "technology" in an extreme "high end" close to commercial type fridge. Certainly not going to happen in ANY household fridge sold at most normal consumer outlets like Home Depot, Lowes and such.

Please don't get me started on the MSW/PSW thing, I have as of yet had very few things not work well with MSW. But keep in mind I DON'T mess around with those $29 2000W junkers. No instead I stay with a GOOD brand name like Tripplite which makes one whopper of a heavy duty MSW inverter.

The one I use for my home fridge conversion is the PV1250, starts and runs the fridge without any additional noise from the compressor. I listened to the sound when running from shore power and from the MSW inverter, NO discernible difference in sound nor sound level of the compressor.

I also checked to see if the compressor ran hotter on MSW, the result was only a couple of degrees and that could have been attributed to the difference in the ambient air temps when I checked it.

For the OP,

While your fridge is RATED at 6.5A, most likely that is including any and all FANS PLUS door heaters and or the DEFROST HEATERS. Basically the name plate rating INCLUDES any and all devices current draw contained within the fridge which may or may not be running at the same time.

I have found in most cases the actual compressor will be about 1-1.2A run draw which translates to about 10A startup surge of the compressor.

If you get the chance, you can remove the back or get to the compressor and read the data plate on the compressor to confirm the draw, this is where the majority of the startup surge happens.

If you don't have the inverter yet I would highly recommend the PV1250, it IS designed to handle heavy inductive motor loads plus it has a neat power save feature called "load sense". It detects if there is a AC load demand and turns the inverter output on. When no AC load is detected it turns the inverter output off. This saves you a massive amount of Ahrs in battery capacity.

Additionally don't skimp on the 12V wiring, that startup surge requires you to ensure the voltage drop from the batteries is very small. 10 ga wires will not cut it, you will need to consider 1/0 and keep it short. I have 6ft of 1/0 (3ft for negative and 3ft for positive) on my inverter, so far have never had any shutdowns or alarms.

So far, my 10 cu ft home fridge is on its 6th camping season and only cost $300 so it is well paid for in my book.

Best to do an at-home Kill-A-Watt analysis for at LEAST A WEEK, to include open door loss makeup. Add an absolute minimum of 115% for inverter loss. Add 15% MORE for CER charge efficiency ratio for the batteries and that'll give you a rough idea of what your BATTERIES are going to ask for.

But how many batteries do you have to keep the fridge running without batteries going dead. Better do a usage calculation.

1500-2000W should cover it.

There a few refer out there now that are three phase run from inverter boards for it. Plus it may have two to three boards running different functions. I would only want a psw inverter for mine. I speak from being authorized service for the majors now retired. I have seen people who go out and spend all kinds of money tearing out there rv frig and replacing it with 2500-3000 dolar refer and cheap out and put some cheap junk modified sine wave inverter in makes me cringe.

Most all the boards are under in the back or on the back panel not a normal installation so you would have to unistall it for a tech to repair it. If its just static coil design just stick it in leave so room for air circulation and put in which one you want. Ya and I know some of you say you run MSW on you big dollar fridge but you pay for that at some point.

our fridge only needs 100w to run, but pulls 900w to start the compressor,
our inverter is 1250w continuous, 1875 for 30 minutes, 2500w for 10 seconds

we need more info about the fridge, make, model#, size

look at the compressor, get the listed LRA amps, from the data plate

LRA is Locked Rotor Amps, the inverter must be able to deliver the LRA for what ever seconds is needed to get the compressor running