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Old 02-28-2015, 02:54 PM   #15
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Reasonably practical.

Originally Posted by the ponz View Post
What would be required to provide 110v ac to the refrigerator while underway?

What size inverter, from where could it be powered?

Is this a practical idea?
The Inverter is the easy part. A 500 or 600 watt unit would easily handle the load. The problem is that you need ten times the current to operate the fridge at 12 volts through the inverter. It will draw about 20 amps from the batteries. At this current level the Inverter will have to be wired directly to the batteries through a 30 amp breaker (separate circuit from your existing breaker box).

This level of current will quickly run down your batteries if the engine is not running. So it is only usable while driving and not an alternative choice for boondocking. The early 3-way fridges were only useable on 12 volts when the tow vehicle engine was running which kept the batteries charged.

You need to set up some protection circuit to disable the 12 volt inverter in case you forget to switch the fridge to propane or shore power after you park. With a 3-way fridge it just switched automatically.

Inverters are relative cheap so the cost is not a big factor. You could also include an outlet socket so you can run a TV or chargers when boondocking.

Forget about running a 110 VAC line from an inverter installed in your tow vehicle. Yes, it is a relative low current level, however it is not safe having that level of voltage on your tow cable. I am pretty sure it is illegal to run this voltage level on the RV to tow vehicle cable.

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Old 02-28-2015, 04:15 PM   #16
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  • Honda EU2000i output = 13.3 amps (full load).

  • Two EU2000i's connected in parallel = 26.6 amps total (calculated)

  • Propane refrigerators do NOT use much fuel. In 78 days of camping full-time last spring (mild rainy weather in the Pacific northwest), one of our 30-pound propane tanks only needed refilling once; and this included using the refrigerator 24/7, heating hot water for showers, and occasional furnace usage for a couple of hours at night.

    In my opinion, the extra cost to power your refrigerator with electricity while underway would never be recovered, compared to using propane. However, if you already own (or plan to buy) a generator for other reasons (e.g., boondocking power), using 120 VAC for your refrigerator may work for you.

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Old 02-28-2015, 04:30 PM   #17
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Originally Posted by WayWard Wind View Post
Moe, with your 2 EU2000 set-up, it produces more than 30 amps. Will this pop the 30 amp breaker & if not why? For instance, if you're running the AC & it cycles off, then the gens will be producing more than needed. Will they cycle down to less than the 30 amps? I have one 2000 unit & I hesitate investing in another, till I'm sure of what I'm doing.
Circuit breakers trip because of excess draw on the electrical supply, not because of the electrical input potential. You can use a 50 amp adapter to connect your 30 amp trailer to city power. I have been at places that only have 50 amp supply. Another time the 30 amp supply was not working so I connected to the 50 amp plug using a 50 amp to 30 amp adapter.

I would not try to exceed 30 amps of draw, as the breaker system of the trailer is set up for 30 amp max.

Look at it this way. You can plug a small, LED bulb into a 15 amp circuit in your home, and it will work just fine, but if you plug in and turn on three electric fry pans and a coffee maker into that same plug, you will blow the circuit breaker. Too much draw.
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Old 02-28-2015, 05:28 PM   #18
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Depends on your fridge, the old Dometic in our Argosy the heating element draws 120 watts and we are running it on an inexpensive 800/450 watt inverter so figuring inefficiency losses ect; it may be taking 13 to15 amps from the battery/alternator. Thats enough to run your battery down pretty quickly if the engine is not running in the tow vehicle.
Two years ago we had a little Toyota motor home with the same setup and did a trip from home (Florida) to Alaska and back a bit over 14000 miles,ran all over Alaska even north of the Arctic circle, fridge worked perfectly and still is as i sold it to neighbor and we are still friends! Would take alot of typing to explain how to do it pretty simply,so if you are interested send me a PM and i will go over it with you.
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Old 03-14-2015, 02:51 PM   #19
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360W @ 120V us is only 3 Amps. what am i missing here? the info i have says, start up of the frig draws 4.5 Amps at 120 V and from that point you have the fan running which is not much of a draw.

also keep in mind that a circuit rated for 30 Amps is only going to provide 24 Amps at full load, 80% of the rating is the standard.
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Old 03-14-2015, 04:28 PM   #20
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It's 3 amps at 120vac but to provide that 360 watts through a theoretically 100% efficient inverter will require 30 amps of 12vdc. Most standard battery banks won't be happy doing that more than a couple of hours.

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Old 03-14-2015, 04:35 PM   #21
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On the other hand, a spiffy new $1500 Novakool RFU 9000 9.1 cu ft reefer with a Danfoss compressor only draws about 4 amps/hr at 12vdc.

One awaits me in the future as my cash flow becomes less sluggish...

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