All,I just took delivery of a new Cardinal 5er. Came with residential Frigidaire Refrigerator, Label says 8.5amp draw The coach also was wired with a Xantrex 2000W ProWatt SW dedicated to powering the refridge(nothing else wired to it), connected to a pair of 6volt GC10 golf cart batteries. Unit is also prewired for a onboard generator for later. All 12v wiring is within 18" between batteries and inverter. We never dry camp, really the inverter is only used when on the road to maintain refridge/freezer temps. Fridge was precooled at home, when I left, I swatched the inverter on, and when disconnected from shore power, reefer continued to run. However, when we got to our destination 2 hours later, freezer had lost 10 degrees over two hours. Refridge maintained its temp. I suspect there are two separate compressors in this refridge.Reading the XAntrex manual, they talk about "exceptional" loads, including freezer compressors. I have to do a little more troubleshooting yet, to see if the inverter is not getting enough DC power to start the compressor spike, but they do go on to say that a larger battery might be needed?Dealer originally had two standard 12 volt batteries wired in parallel, but I told him I wanted a pair of 6 volt deep cycle wired in series.Whats the recommendation here? should I have stuck with the dual 12V in parallel?

What size wires are connecting the battery to the inverter? 18" is good but they still have to be fairly thick. It's probably drawing on the order of 90amps-12v.I would test at a site. Disconnect the shore power and see if the fridge kicks on if you turn the thermostat down. 10 degrees loss in an hour could imply it wasn't running at all and just functioning as a built in cooler. 8.5amps would be about 1000watts but typically getting a compressor to kick over takes 2-3 times the amps, so 2000watts would be marginal to get it started.

I think the best way to troubleshoot this is to try running the fridge on inverter at the house for several hours prior to taking a trip. This way you can watch things and see what is happening. I don't know about the Frigidaire but the Samsung RF18 has two compressors. The 8.5A draw on 110vac seems awfully high. You can roughly figure the DC amperage draw on the batteries as 10 times the AC current draw, so 8.5A AC would be around 85A DC on the batteries. I personally went with dual 12V batteries but yours should work. Experiment with it at the house and good luck.

valhalla360 wrote:What size wires are connecting the battery to the inverter? 18" is good but they still have to be fairly thick. It's probably drawing on the order of 90amps-12v.I would test at a site. Disconnect the shore power and see if the fridge kicks on if you turn the thermostat down. 10 degrees loss in an hour could imply it wasn't running at all and just functioning as a built in cooler. 8.5amps would be about 1000watts but typically getting a compressor to kick over takes 2-3 times the amps, so 2000watts would be marginal to get it started.1GA. My plan is to try that today at our current campsite today. Xantrex manual indicates that the inverter is good to 3000 watts surge, 1800 watts continous.

I wouldn't think you would have 2 compressors. Maybe the thermostat is located in the fridge only and the freezer just lost temp going down the road do to location and heat in the rig while traveling. I will be curious to see what you find out. Keep us informed.

What wire gauge was recommended from batteries to inverter in the inverter installation manual for your length wire run?1 Gauge is very likely too small.And pretty easy to check:Check voltage drop across the wires-- when someone starts the refrigerator, with a digital voltmeter check voltage between house battery positive and negative lugs.Check again at the inverter positive and negative lugs. Any delta between the two means resistance in the cabling. 2% drop is commonly recommended for primary circuits.While large gauge wire is not inexpensive, it is sure the least expensive "fix".

Inverter/Battery/load combination | Good Sam Community

16 Replies

djousma
Explorer
Jul 01, 2016
So, I went and took a closer look at all the 12V connections. All were snug, but not tight. Snug meaning, i could move them on the terminal with moderate force. I have since tightened them all down, including on the inverter itself which were also only snug. Been running for an hour now, no problems.

My batteries were not dead when I arrived at the campsite, as the fridge was still operating, and I was able to lower landing gear, push slides out, etc before plugging in to shore power, so the batteries had to be maintained while driving too. I didnt check the highly subjective "battery gauge" at the time.

There were no audible alarms either, so not sure what was going on. Maybe all the jostling around while driving down the highway caused problems? Like I originally mentioned, refridge temp was at the set point, it was only the freezer that was at +11(setpoint 0).
wolfe10
Explorer
Jul 01, 2016
What wire gauge was recommended from batteries to inverter in the inverter installation manual for your length wire run?

1 Gauge is very likely too small.

And pretty easy to check:

Check voltage drop across the wires-- when someone starts the refrigerator, with a digital voltmeter check voltage between house battery positive and negative lugs.

Check again at the inverter positive and negative lugs. Any delta between the two means resistance in the cabling. 2% drop is commonly recommended for primary circuits.

While large gauge wire is not inexpensive, it is sure the least expensive "fix".
dave17352
Explorer
Jul 01, 2016
I wouldn't think you would have 2 compressors. Maybe the thermostat is located in the fridge only and the freezer just lost temp going down the road do to location and heat in the rig while traveling. I will be curious to see what you find out. Keep us informed.
djousma
Explorer
Jul 01, 2016
valhalla360 wrote:
What size wires are connecting the battery to the inverter? 18" is good but they still have to be fairly thick. It's probably drawing on the order of 90amps-12v.

I would test at a site. Disconnect the shore power and see if the fridge kicks on if you turn the thermostat down. 10 degrees loss in an hour could imply it wasn't running at all and just functioning as a built in cooler. 8.5amps would be about 1000watts but typically getting a compressor to kick over takes 2-3 times the amps, so 2000watts would be marginal to get it started.

1GA. My plan is to try that today at our current campsite today. Xantrex manual indicates that the inverter is good to 3000 watts surge, 1800 watts continous.
lynndiwagon
Explorer
Jul 01, 2016
I think the best way to troubleshoot this is to try running the fridge on inverter at the house for several hours prior to taking a trip. This way you can watch things and see what is happening. I don't know about the Frigidaire but the Samsung RF18 has two compressors. The 8.5A draw on 110vac seems awfully high. You can roughly figure the DC amperage draw on the batteries as 10 times the AC current draw, so 8.5A AC would be around 85A DC on the batteries. I personally went with dual 12V batteries but yours should work. Experiment with it at the house and good luck.
valhalla360
Navigator
Jul 01, 2016
What size wires are connecting the battery to the inverter? 18" is good but they still have to be fairly thick. It's probably drawing on the order of 90amps-12v.

I would test at a site. Disconnect the shore power and see if the fridge kicks on if you turn the thermostat down. 10 degrees loss in an hour could imply it wasn't running at all and just functioning as a built in cooler. 8.5amps would be about 1000watts but typically getting a compressor to kick over takes 2-3 times the amps, so 2000watts would be marginal to get it started.

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Inverter/Battery/load combination

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