Inverter for fridge

[oediehl]

About a year ago I decided I'd have enough of  our wimpy Norcold 1200 absorption fridge, and pretty much rebuilt it. I used the Amish Dutch Aire cooling unit (supposedly superior to Norcold's unit), new circuit board, fans, heating elements, and even an ARP device to prevent damage from overheating. It works just fine, unless it's hot outside, in which case the unit warms back up to unacceptable temps. Perhaps I didn't get the new cooling unit sealed or seated well enough, but after redoing it again and seeing no improvement, I've decided to do what I wish I'd done the first time around; that being replacing it with a residential unit, with an inverter for when we're driving from site to site. No Boondocking for us. Home Depot has the Samsung RF18 on sale, so I think that is what I will purchase.

What I'm thinking about now is the inverter. I only plan to use it when driving from campground to campground; otherwise it will be shore power, or the fridge is turned off. If I get an inverter with an internal transfer switch, I'm thinking that I can basically just insert it into the existing wiring for the outlet that now powers my Norcold (and also wire it to the battery input), and that should serve my purpose. When shore power or the generator is on, the inverter will just pass that through to the fridge, otherwise it will draw 12V from the batteries and use that to power the fridge. Sound correct?

 

[Kevin Means]

Welcome to the RVForum. It would be the battery's output that gets wired to the inverter, but other than that, you've got it right. To get the most out of the inverter, install it as close to the battery-bank as possible, and use an appropriate gauge wire.

Kev

 

[Gary RV_Wizard]

About the only drawback to your plan is that an inverter failure takes the fridge out as well.  It's not difficult or expensive to add a DPDT switch to enable either the inverter or the existing load center circuit breaker to provide 120v power to the fridge. That gives you an easy back-up power source. You could still leave the inverter as the primary source if you like.

 

[judway]

I installed a Whirlpool 10 cf refrigerator a couple of years ago and it has worked great ever since. It is setup to operate on shore power when available and the battery and inverter when shore power is not available. You can search for my posts by going to search and typing in refrigerator inverter, also type in judway for the author.

Next is an approximate cost of the installation:

Xantrex Prowatt 806-1220 Sw2000 2000W True Sinewave Inverter    $350
A 1 kW unit will cost about $250
Xantrex - Prowatt SW Remote Switch Panel    $25
Xantrex Inline Transfer Relay for Prowatt SW  $55
4/0 Battery cable 2 pieces about 10? long with terminals  $110
Panel 120 VAC Voltmeter and 200 Amp DC Ammeter    $30

I used the 1kW unit. Total cost about $360 for parts

All of my stuff was purchased on eBay.
Lots of work

 

[retusn]

I just installed a residential frig in my allegro as my Dometic stopped working.  I understand the inverter part, I just don't know where/how to tie into the circuit that the frig is running on now.  I am also thinking about installing a couple boxer fans in the roof frig vent.  I will be following this to see how things work out.  BTW, I did not intend on stealing this thread.

 

[oediehl]

Anyone have a link to a DPDT switch, so I can look and be sure I understand?

 

[Rene T]

I installed a res fridge last year with a Xantrex pure sine wave 1000 watt inverter. I also used one of these. It automatically swaps over to shore power when I plug in. It's not cheap but it's all automatic.  The fridge runs great while traveling.

https://www.thepowerstore.com/xantrex-prowatt-sw-15a-remote-transfer-switch?gclid=CLO33tvW79QCFYtXDQodRBgL8Q

I also installed a remote switch in the kitchen. We use this when we stop for the night. I just unplug from the truck and shut off the inverter with this swtch so it doesn't drain the RV battery overnight. I'm not sure if it would because the fridge would not run all that much as long as we careful when opening the door.

https://www.amazon.com/Xantrex-808-9001-PROwatt-Remote-Switch/dp/B002W87JNO

 

[Gary RV_Wizard]

This tutorial on switches may help:
https://learn.sparkfun.com/tutorials/switch-basics/poles-and-throws-open-and-closed

Basically the DPDT switch is used here to switch both hot and neutral wires from one power source to another. The fridge power wire is connected to the center (load) pair of terminals on the switch and the two power sources (inverter and shore-direct) to the others, one source per pair. The ground wire does not need to be switched in this case.

As Rene says, there are inverters that have a built in transfer switch, an automatic DPDT that is triggered by the presence or lack of external 120vac power.  The inverter has both battery and shore power connections and the inverter output goes direct to the fridge. This works great as long the inverter & its built in switch are functional.

The attached diagram shows a DPDT switch feeding a fridge from either an inverter or direct shore power. The diagram uses a single colored line to represent each pair of power wires (hot & neutral)

 

[oediehl]

So in this pic, shore power would go to 1P/1T and 2P/1T, and the inverter output would go to 1P/2T and 2P/2T, and the switch would switch between the 2?

 

[judway]

Xantrex makes a transfer switch for this purpose. Xantrex Inline Transfer Relay For Prowatt Sw [808-0915] cost about $60 on ebay.


You can look at the instruction manual at: http://www.xantrex.com/documents/Accessories/PROwatt-Transfer-Switch/975-0588-01-01_Rev-A(Auto%20Transfer%20Switch).pdf

 

[Jeff]

I installed a Xantrex Pro XM 1800 (Also comes as 1000) Watt Inverter that includes auto switching and remote control. It is connected to our house batteries and is also fed by the circuit breaker that supplied AC current to our old fridge. Our Norcold had a second outlet behind it that supplies power from the coach inverter for the old icemaker so if the new inverter quits I can plug into that.

The  primary reason I installed the second inverter was to shut off the big inverter if we were boondocking because of its overhead load.  It is also nice to start up and not forget to switch on the inverter before o pulling out as it always on.

 

[Rene T]

Xantrex makes a transfer switch for this purpose. Xantrex Inline Transfer Relay For Prowatt Sw [808-0915] cost about $60 on ebay.

There must be a echo in here.  : ;D