Running 3 way fridg on inverter power

Dalehelman

In over 40 years of RVing we have always had the standard propane / 110 volt powered refrigerator. No complaints they have always served us well. We have traveled thousands of miles with the propane on with no issues. Except that the flame can be subject cross winds and go out. Not a problem since the gas also shuts off. The problem with the newer electronic ignition is it try’s to restart and can’t because the start button must be held in. As a result it keeps trying to start until we stop and realize it has flamed out. 

Since the 12volt function isn’t really able to maintain proper cooling, but the 110 volt function works equally as well as propane. I am considering using the 110 function while traveling.

The draw on 110 is about 150 watts at 1.2 amps. I have a 300watt pure sine wave inverter. 

I have 2 options. One I can plug the inverter into a 12volt outlet in the trailer the plug fridg 110 cord into the inverter. My second option is to plug inverter into my tow vehicle and run an extension cord back to fridg.

Looking for input. Your thoughts.

Sharon_is_SAM

@Dalehelman - someone did this.  Maybe @RollingLagrima?

Sharon_is_SAM

Nope, it was @RollingBnB.

https://tab-rv.vanillacommunity.com/discussion/comment/82046#Comment_82046

Dalehelman

Sharon_is_SAM said:

Nope, it was @RollingBnB.

https://tab-rv.vanillacommunity.com/discussion/comment/82046#Comment_82046

Funny I started that thread. It morphed into the inverter thread later. I apparently didn’t follow it to the end. 

GibW

Have you considered a DC to DC charger? 

Dalehelman

GibW said:

Have you considered a DC to DC charger? 

Unfamiliar 

MuttonChops

Dalehelman said:

One I can plug the inverter into a 12volt outlet in the trailer the plug fridge 110 cord into the inverter. My second option is to plug inverter into my tow vehicle and run an extension cord back to fridge.

Assumption (a) your wish to run on 120VAC is to get temperature control and to protect your T@B battery from discharge as happens during Fridge 12VDC operation.

As noted in the referenced older thread the total power used is the same on 120VAC and 12VDC. If you use installation method One then you will still be running theT@B battery down because the inverter will be drawing >11 Amps and your TV +12VDC charge line won't keep up . . . same problem/risk as just running Fridge on 12VDC but now you have temperature which will cycle power demand off-on.

So your Second Option might be the better of the two; Fridge on 120VAC but T@B is not in the feed circuit to the inverter so battery won't be drained.

For DC-DC Convertor method I've been considering the Sterling Power Wildside BBC1225.  It is a smart battery charger and has a second trailer Fridge output.  The Fridge output will cycle off-on when the Wildside detects the battery needs a greater amount of charging current.  Price of course the biggest reason I've not installed one so far.

Sharon_is_SAM

I think that the frig on 12 v draws so much because you can not control the temperature.  While on 120v, the thermostat is effective, so less cycling and less power draw?

Dalehelman

I am not as concerned about the power draw. If I understand it seems to be about the same. It’s just that the frig works perfect on 110. Where on 12 volts it is almost worthless. Generally I know just enough about electricity to be dangerous. 

Thanks @MuttonChops for your input. I knew I could count on you.

webers3

@Dalehelman i tried option 1 for exactly the same reason using a 300 watt inverter but could not make it work, the inverter kept shutting off, i did not investigate it any further, one thought i had is perhaps the 12v outlet couldn't provide enough current?

Dalehelman

webers3 said:

@Dalehelman i tried option 1 for exactly the same reason using a 300 watt inverter but could not make it work, the inverter kept shutting off, i did not investigate it any further, one thought i had is perhaps the 12v outlet couldn't provide enough current?

So far it has been running all day. Eighty degree temperature in the shade. The temp setting is in the middle. It took about 2hours to bring it down to 40 degrees. I just lowered the temp setting should be able get it to 35 degrees.

webers3

@Dalehelman which inverter are you using? 

Dalehelman

@webers3
I have a Bestek 300 watt pure sine wave inverter. I purchased it from Amazon for $49. I have been unable to find it there currently. There are other similar products there though.

RollingBnB

I used a 200 watt inverter but ran some 10 gauge wires directly to the battery. We went as far as New York and back without any issues.

webers3

@Dalehelman thats what i have, will have to give it a other try, thanks. 

BrianZ

@Dalehelman, for your test on the 18th, were you using option 1 (inverter plugged in to T@B 12V)?
And for traveling, if you will use option 2, to plug inverter into TV & run 120V extension cord to T@B frig, how will you route that cord from outside to inside the T@B?
I would like to try this sometime.
PS: Does the Norcold really need a pure sine wave inverter?  I only have this one..

Wattage should be enough, but not sure if pure sine wave is required.

Dalehelman

@BrianZ
On my test the trailer was plugged into 110. The inverter was plugged into a 12volt outlet. The fridge was plugged directly into the inverter. The seven pin does not provide enough power to maintain the battery. The best solution seems to be plugging the inverter into the tow vehicle with an extension cord to the trailer. One simple way is through the front window. In my case my generator is mounted on the tongue. I can unplug the generator and plug that cord into the inverter.

Up date. My Jeep GC has 110 inverter outlet rated at 150 watts which seems to run the fridge just fine . I will have to wait until our next trip to see if in fact it works. If it does the inverter will be on its way back to Amazon and I save $50.

BrianZ

Thanks @Dalehelman,
That sounds like a great plan.  And I would agree that it's better to send that power over the longer distance to the T@B by using the low amp/high voltage AC power to reduce loss (same principle the power companies use).  As long as your vehicle can send the amps.
How convenient that your generator is already wired into your system! - how does that cable get inside anyway?

I was thinking how close our fridge plug is to the plumbing vent stack that goes outside from same cabinet, and whether it might be possible to mod the plumbing stack vent pipe at some point to pass an extension cord out through the driver side/front vent. Maybe at the horizontal pipe behind the toilet for example, with a Y-connector with screw cap to temporarily pass the cord outside for travel.  Might be safer on a rainy day than going through the front window. 

In any case, looking forward to hear how it works for you.  Just need to turn it off when stopped I guess.
I think my non-sine wave inverter should work, since it would mainly just be powering a heater in the frig.  I haven't studied the electronics.  Is your jeep's inverter sine wave or not?

Dalehelman

@BrianZ
Your vent pipe sounds doable. My choice would be a marine through deck water proof cable fitting. Into the front storage tub. First choice would still be the front window, and just pass if the weather is bad.