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Old 07-19-2020, 09:41 PM   #1
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Refrigerator

Just came back from the marina. Talking with some boat owners about our refrigerator which is a marine 120v/12v model. They told me I should leave the frig running on 12v even when at the dock. Not sure if that’s a good idea or not.
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Old 07-19-2020, 09:50 PM   #2
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That is what I have done and my last two boats. if I did the dock the battery charger picks up the load
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Old 07-19-2020, 11:30 PM   #3
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Does the fridge convert 120v to 12v? If so, hard to see why using 12v is better. Maybe exercising the battery charger? What reason did the neighbours give? Someone will know.
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Old 07-20-2020, 06:28 AM   #4
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Some refrigerators will automatically switch over to 110V when you are connected to shore power or generator power, then back to 12v when no AC power is detected. Do you have to switch yours manually?
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Old 07-20-2020, 06:36 AM   #5
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If it automatically switches when it senses shore power, I'd let it run on shore power and let the batteries rest. I doubt there is any savings in running off the battery and then recharging the battery as recharging certainly isn't 100% efficient.

That said, if the 120 VAC side quit, I would certainly run the refrigerator off the battery all the time.

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Old 07-20-2020, 06:55 AM   #6
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Either keep the fridge running or empty it and tape the door open.
Some people get great joy from unplugging a boat. On the n46, happened to me 2 or 3 times and it was a mess to clean up. The AT has a 12vt fridge. When I came back after 2 months, I was fine, I had also installed a couple of solar panels to keep the batteries up. Fooled those bastards.
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Old 07-20-2020, 07:27 AM   #7
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Most duel power frig are automatic 118 on shore then 12 on house if wired that way. Most efficient. 118 vac alone is option wire to boat AC and when off dock power off inverter. Less efficient that way though with inverter loss.
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Old 07-20-2020, 07:57 AM   #8
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I have 3X4D batteries and if I ran the inverter to support a 120vt fridge, I doubt if I could support the fridge as long, so I am happy with the 12vt fridge.
There are a lot of losses through the inverter. With the solar panels, supporting just the fridge and lights and and TV, I can go for days, assuming I not parked in the shade. Even on a gray day, I can see some input from the panels.
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Old 07-20-2020, 08:27 AM   #9
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Every Dual Voltage fridge I've ever owned defaults to AC when present and only switches to DC when there is no AC. By turning on both breakers, if the dock looses power, your fridge stays runnng.

The other side of this coin is....if the dock looses power, your fridge drains your batteries and you no longer have bilge pumps. The assumption is that the dock power loss will be temporary.

We leave both on.
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Old 07-20-2020, 08:51 AM   #10
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I have breakers for the 110v and a breaker for the 12v. I usually leave the the 110 on at the dock and switch the 12v on when away from the dock. They told me that even though the 110 is on at the dock the refrigerator still knocks it down to 12v. Not sure if that makes sense or not.
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Old 07-20-2020, 10:11 AM   #11
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Quote:
Originally Posted by gonesailing13 View Post
I have breakers for the 110v and a breaker for the 12v. I usually leave the the 110 on at the dock and switch the 12v on when away from the dock. They told me that even though the 110 is on at the dock the refrigerator still knocks it down to 12v. Not sure if that makes sense or not.
They're saying the compressor is 12 VDC and the 120 VAC is being converted to 12 VDC.

Ted
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Old 07-20-2020, 10:30 AM   #12
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They're saying the compressor is 12 VDC and the 120 VAC is being converted to 12 VDC.

Ted

Except if the people saying that are talking about a Danfoss compressor based fridge, they're incorrect. The compressors in those are fed inverted 3 phase AC, so the control module isn't feed power straight through when operating from either source.
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Old 07-20-2020, 10:44 AM   #13
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i kind of do the opposite i leave the 120 on when leaving the boat and turn the 12v off .mine has 24v fans and compressor it converts ether voltage to 24v .it must have a capacitor to cover the switch the compressor hums normally when switching . my dock can go under water in high sustained wind when it does they turn off the power , i would rather loose my ice cream than my bilge pumps.
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