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Old 05-16-2015, 03:28 PM   #1
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Inverter power to newly installed residential refrigerator

Good day to all.

I am trying to solve an inverter voltage issue for the new Kenmore residential refrigerator (115VAC; 7.2amp) that I installed last week. The refrigerator runs fine off shore power and generator power but not well on inverted power. Measured voltage at the refrigerator outlet shows shore and generator power at 121-123VAC but the inverter power to the same outlet is only 102-105VAC. Other outlets (non-refrigerator) measure similarly (102-105VAC) when I'm running on inverter only. Typically those outlets service low power items like clock radio, tooth brush, etc.

My current house battery configuration is four 6VDC AGM “extended life” units from East Penn Manufacturing (Brand name is Intimidator.) According to their spec sheet the part number is 8AGC2; CCA@zero degrees=680; Res. Capacity=380; 20AH rate=190. East Penn Manufacturing | Recreational vehicle batteries

The house battery load test results I ran are: (Each battery was disconnected from others before testing)

Battery 1: Before load = 6.45VDC; after load = 6.41VDC
Battery 2: Before load = 6.49VDC; after load = 6.40VDC
Battery 3: Before load = 6.45VDC; after load = 6.40VDC
Battery 4: Before load = 6.51VDC; after load = 6.38VDC

Testing of the AGM batteries, as seen from above data, did not seem to find anything wrong. So, I’m not sure what all this tells me, but clearly running the refrigerator on the inverter is not going to happen yet. I speculated that I might have a faulty outlet, but since both shore and generator feed the same outlet, I concluded that that was not the problem. Correct me if I'm wrong and need to revisit that thought.

Here's my current options as I see them:

Option 1 - Adding additional batteries. My understanding is that adding batteries increases voltage and capacity (i.e., the amount of time you can run on house battery power.) Adding two more would give me a nominal 36VDC (6x6) versus my current 24VDC (6x4), and 1140 Amp hours versus the present 760 Amp hours. Is this the simplest solution to my problem? If so, how many to add? Space may be an issue but I’ll worry about that if this option is the answer.

Option 2 – Upgrading inverter. I have a Xantrex RV2012GS, 2000watt, 12V inverter. Not sure what this would do but have been told my inverter should handle the refrigerator addition with no problem. Others who have done similar refrigerator upgrades with this inverter have not had problems.

Option 3 – Adding a dedicated inverter for the refrigerator. I’m not sure what this accomplishes either and would need more explanation and research.

If anyone has any thoughts, I’d appreciate your comments and feedback. Thanks.



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Old 05-16-2015, 04:19 PM   #2
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Your inverter is a modified sine wave inverter. I would imagine your refrigerator requires pure sine wave A/C power. If you don't have the manual, it does suggest problems with certain motors, especially compressors.

http://www.xantrex.com/documents/Inv...-01_Rev-A).pdf
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Old 05-16-2015, 04:46 PM   #3
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The voltage from your inverter is too low. More batteries will only increase the amount of time you can run the fridge but will not increase the voltage coming from the inverter.
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Old 05-16-2015, 05:06 PM   #4
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Quote:
Originally Posted by Golfwannabee View Post
Option 1 - Adding additional batteries. My understanding is that adding batteries increases voltage and capacity (i.e., the amount of time you can run on house battery power.) Adding two more would give me a nominal 36VDC (6x6) versus my current 24VDC (6x4), and 1140 Amp hours versus the present 760 Amp hours.
Your understanding on Option 1 is not correct. The 4 batteries you now have should be wired as a bank of two batteries in series which gives you two banks of 12VDC, then those two banks wired in parallel which gives you a total of 12VDC but at a higher amperage. Adding two more batteries would still give you 12VDC at a higher amperage which equates to longer run time when on the inverter. Your Invertor uses 12VDC and should provide you 110-125VAC.

The output of the inverter seems a little low, but IF the frig can run off a modified sine wave then it should run fine. However, I suspect the frig needs to see a full sine wave AC voltage and thus is not going to run on your inverter.

Check the manual, if you can't find it there then call the manufacturer and ask them if your frig will run on a modified sine wave signal, if not then all you should have to do is replace the inverter.
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Old 05-16-2015, 05:17 PM   #5
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The above answers are correct in my opinion but with one other observation. Your voltage is too low out of the inverter. Remove power from everything and tighten every electrical connection you can find; transfer switch, service panel, inverter, and check the condition of that outlet. If the inverter, at the AC output terminals, is reading that low replace the inverter. I am partial toward Magnum Pure sine wave inverters. They, in my opinion, are worth the bucks.

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Old 05-16-2015, 05:30 PM   #6
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Most modern refrigerators and other electronic require a pure sine wave Inverter. They will not work or will only work erratically on a modified, cheap, inverter. Do you know if your inverter is a pure sinewave or modified?
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Old 05-16-2015, 05:36 PM   #7
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I just pulled up the manual on the website and it says it's a modified sinewave so I would bet money that that is the reason you are having problems. May want to ask Kenmore if it will work on a modified sinewave.
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Old 05-16-2015, 06:00 PM   #8
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The low voltage reading is because you require a true RMS volt meter to read a m sine wave. The voltage will truly be 120. But as other people have stated your fridge will not run on a M sine wave
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Old 05-16-2015, 06:03 PM   #9
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Swap the MSW inverter for a PSW inverter of the same capacity. Done.
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Old 05-16-2015, 06:05 PM   #10
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All the above comments about low voltage could be a result of the modified sine wave signal.
This is from the manual of a modified wave inverter: "The output waveform of the AC Inverter is a MODIFIED SINE WAVE. If you choose to measure the AC output voltage, you must use a TRUE RMS VOLT METER. Using any other type of voltage measuring device will resulting an AC voltage reading of 20 to 30 volts lower than the rated value. When using a true RMS volt meter, you will get an accurate reading."
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Old 05-16-2015, 06:09 PM   #11
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It sounds like you do not understand what your meter is telling you or how AC voltage is measured. Low readings are reasonable with non sinusoidal waves like come out of an MSW inverter. The question is how well the refrigerator tolerates power in that shape waveform. If the compressor is not running hotter I would leave it alone.
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Old 05-16-2015, 06:14 PM   #12
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What size battery cables are running to your inverter?

Are any alarms or light, on the inverter, going off, when you turn on the refrigerator?

They should be at least 2 gauge for your setup. 00 gauge would be better, for any distance.

With a MSW, inverter, your volt meter could be wrong.

You have a 12 volt inverter. 2, 6 volt batteries in series run it. Then you have a second set of 6 volt batteries, in parallel, with the first set, still keeping the volts at 12 volt.

You need to understand this before adding batteries.

Good luck
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Old 05-16-2015, 11:07 PM   #13
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Quote:
Originally Posted by newmar10 View Post
The low voltage reading is because you require a true RMS volt meter to read a m sine wave. The voltage will truly be 120. But as other people have stated your fridge will not run on a M sine wave
I was going to give newmar a gold star until he said a refer wouldn't run on a MSW.

The correct answer to the MSW vs. PSW is that some will run fine, others won't. Either way all will be happier running on a PSW
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Old 05-17-2015, 06:10 AM   #14
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There are two kinds of voltmeters.. I have both here.. When using an MSW invrter the will not agree.. One kind (the cheapest) reads low the more expensive True RMS meter reads accuratly.

Adding more batteries will not increase inverter output voltage

What inverter do you have

And I noticed you were measuring voltages on SIX volt batteries

YOU DO NOT HAVE SIX VOLT BATTERIES when installed.. Just 12 volt batteries that come in 2 parts for ease in handling.. Treat each pair as though it were a single battery.
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