2017 Sunstar LX Fridge on Zantrex 1000 Inverter Circuit

TigeDuner · 11-28-2023, 10:21 AM

Hi all,

We just purchased a 2017 Sunstar LX 35F with a new residential fridge that was installed by the local RV dealer at the request of the previous owner. The OEM fridge was propane/110v and the previous owner said he wanted to upgrade due to issues with the OEM unit. The RV came with a Xantrex 1000 watt inverter and a 175 amp alternator. The new fridge draws 1.2 amps according to the data plate inside the fridge, which I believe equates to about 14 amps DC.
It appears that the dealer did not put the new fridge on the inverter circuit, which I would have preferred so it could be on while we are driving. I removed the fridge cover on the exterior of the RV and was able to gain access to the fridge outlet inside the compartment. I am not sure if this was an existing outlet for the OEM fridge or added during installation of the new fridge.
Our inverter is on the side wall of the exterior compartment that is below and to the rear of the fridge so it would be easy to get power from the inverter.
I disconnected the shore power to the RV, turned on the inverter, and the fridge did not come on, but the outside TV did so I know the inverter is working.

Is it possible to plug the fridge into the outlet on the inverter and have the fridge run while driving AND run on shore power when the inverter is off?

Also, I cannot find a wiring diagram for the outlets that are powered by the inverter when I look thru the Winnebago wiring diagrams for our RV. Any help would be appreciated.
TD

tim myers · 11-28-2023, 10:41 AM

Short answer is yes, but how it works is dependent on how your inverter is set up. Many inverters only invert dc voltage to ac voltage. If this is how yours works it will work but there will always be a draw on your batteries even when plugged into shore power. But there is really nothing wrong with that.

Newer and usually larger inverters have both dc and ac inputs and when plugged into shore power the ac voltage is passed through the inverter and on to the ac loads. When the inverter detects that ac power has been removed there is an internal transfer switch that allows the dc voltage to pass to the inverter section and make 120 volt power.

TigeDuner · 11-28-2023, 12:20 PM

Thanks for the reply. Below are the specs on the Xantrex Inverter. It appears to have a pass thru for 110v power, but I am not sure if it has to be hardwired or thru the inverter GFIC.
https://www.hodgesmarine.com/xan806-...ter.html?nis=6

TigeDuner · 11-28-2023, 02:07 PM

Hey Tim,

After your comment about the batteries continuing to be used, I decided to call Xantrex for their help. They said that there is an automatic transfer switch in the inverter that will allow the 110v power to "pass thru" the inverter and cut off the battery usage until the shore power is disconnected, then the batteries take over again. He also said that I can hard wire the fridge to the inverter circuit or plug the fridge in the inverter outlet with the same results. So, thanks for your comment - looks like I am able to now use the fridge while driving once I get it connected to the inverter.

I do still need to find out which outlets are on the inverter circuit, which I suppose I can do by checking each outlet with a tester.

TD

**creativepart** · 11-28-2023, 02:32 PM

Hi TD, I think the normal way to effect this would be to move that AC outlet behind the fridge to the Inverter side of the circuit panel.

I'm not all that good with electric systems, so, this is very shaky info, but I would guess that your AC Power Center has two branches - one not on the inverter that has your A/C unit, Water Heater, and all the outlets in the RV that are not powered by the inverter. And then there is also an inverter branch in the circuits that has all the TVs and the outlets that are powered by the inverter.

So, theoretically in my mind at least, all you need do is find the circuit breaker for that outlet behind the fridge and move it to that inverter branch of the power center.

What I would do is find a mobile tech with AC electrical chops to come and make this move for you.

FYI, when Winnebago installs a residential fridge they also install a 2000w inverter/charger (eliminating the Converter in the RV) and 2-extra house batteries. They also add the microwave circuit to the inverter side of the Power Center.

**creativepart** · 11-28-2023, 02:40 PM

I looked up your 2017 Sunstar LX 37F's wiring diagram. I don't know if the panel layout is the same you have - because it might for for optional equipment that you don't have. But perhaps the concept is the same.

See how there is an Inverter Subpanel on the right? According to videos I've seen you simply physically move the circuit breaker on the Left that services that outlet behind the fridge to the Inverter Subpanel on the right.

DO NOT TRUST THIS INFO - I'm a hack that knows next to nothing. Just trying to put you on the right track.

TigeDuner · 11-28-2023, 10:43 PM

Unfortunately, we have a 35F and not a 37F so it may not be that easy.
TD

l1v3fr33ord1 · 11-29-2023, 04:03 AM

TigeDuner-

It appears as if Winnebago changed the 110/120V side significantly in the middle of the 2017 Sunstar LX model year. Does your coach's serial number begin with 70E75W1 (early) or 70E75W2 (late)?

2017 diagram sets (early and late) are here.
2017 early (70E75W1) for 35F are here.
2017 late (70E75W2) for 35F are here.

The "Body, 110 Volt Wiring Installation/Diagram," last page, shows what is connected to the inverter outputs. The "110 Volt Load Center/Auto Transfer Switch" contains other helpful information.

Knowing the serial number we can offer options for how to get inverted 120V to the refrigerator.

One more thing: Could you please confirm:

1) Yours is a 50A coach, and
2) Somewhere your coach has a Precision Circuits Mini-PCS control panel, as shown in this link.

TigeDuner · 11-29-2023, 09:43 AM

Our RV is 70E75W1 and it has a 50 amp service. The mini-PCS control panel is located above the main TV. I looked thru many of the wiring diagrams, but did miss the one with the inverter, which is helpful.

The plug on the end of the fridge cord is accessible thru the cover on the exterior of the RV and is only about 2 feet from the outlet on the front of the inverter. I can plug the two together to confirm that the fridge works with the inverter on and the engine running.

TigeDuner · 11-29-2023, 09:28 PM

Well, that was encouraging - I plugged the fridge into the outlet on the inverter and all worked well with the engine running and shore power disconnected. I was also able to find several of the outlets on the inverter circuit. So, all that is left is to either rewire the fridge outlet to the inverter circuit of find a path to get the fridge cord to the inverter outlet, which may be easier since the inverter is so close to the fridge.
Thanks for your help guys,
TD

l1v3fr33ord1 · 11-30-2023, 04:57 AM

TigeDuner-

I took a look at some of the candidates for redirecting an existing inverter-fed outlet to refrigerator service, and determined none of them were great candidates.

As you say, the simple solution is to either find an existing hole or make a small one for the refrigerator cord to pass through to the inverter.

There may be a safety rule somewhere that prohibits/discourages running electrical cords through holes. If so, or if that is your inclination, then you could wire a second outlet behind the refrigerator to the inverter outlet, with a plug on the inverter end. I did that in my coach. I could manually swap between inverter (when on road) and shore power (when stationary) outlets from outside the coach. On shore power the inverter was out of the reefer circuit. I even bought a little Xantrex 15A transfer switch to do the swap automatically, but never installed it.

The refrigerator may be the largest load on the inverter, so being able to switch it to shore power would reduce the inverter load.

By the Winnebago diagrams your Precision Circuits EMS is wired to shed the existing refrigerator circuit when on 30A shore power. That may have been OK with a propane-electric reefer, but isn't suitable for a residential. If you plan on using the existing outlet, I'd think about reconfiguring the EMS or wiring to eliminate that shed logic.

TigeDuner · 11-30-2023, 06:43 AM

Mark,

I will verify today if the fridge works on shore power when plugged into the inverter. The inverter has an automatic transfer switch built in, to allow 110v to "pass thru". I noticed yesterday that the main TV would not power up on the inverter and found it plugged into an outlet that was not on the inverter circuit. Once I changed it to a different outlet under the TV, it came on. I turned the inverter off and the TV turned off, and then I connected the shore power and the TV came back on. More to come.

TD

TigeDuner · 11-30-2023, 01:44 PM

The fridge worked fine plugged into the inverter with the inverter off and shore power connected. Looks like the pass thru feature worked as designed. Now its time to find a route for the fridge cord to the inverter, which will be thru the furnace cavity under the fridge and thru the compartment wall, which the inverter is mounted to.

Hopefully this will help others when replacing a gas/elec. fridge with a residential unit.
TD

Bobn1957 · 12-03-2023, 04:19 PM

Quote:

Originally Posted by l1v3fr33ord1

TigeDuner-

I took a look at some of the candidates for redirecting an existing inverter-fed outlet to refrigerator service, and determined none of them were great candidates.

As you say, the simple solution is to either find an existing hole or make a small one for the refrigerator cord to pass through to the inverter.

There may be a safety rule somewhere that prohibits/discourages running electrical cords through holes. If so, or if that is your inclination, then you could wire a second outlet behind the refrigerator to the inverter outlet, with a plug on the inverter end. I did that in my coach. I could manually swap between inverter (when on road) and shore power (when stationary) outlets from outside the coach. On shore power the inverter was out of the reefer circuit. I even bought a little Xantrex 15A transfer switch to do the swap automatically, but never installed it.

The refrigerator may be the largest load on the inverter, so being able to switch it to shore power would reduce the inverter load.

By the Winnebago diagrams your Precision Circuits EMS is wired to shed the existing refrigerator circuit when on 30A shore power. That may have been OK with a propane-electric reefer, but isn't suitable for a residential. If you plan on using the existing outlet, I'd think about reconfiguring the EMS or wiring to eliminate that shed logic.

If you do run the cord through a hole, seal it in with RTV to prevent the cord from chafing and causing a problem down the road!

TigeDuner · 12-03-2023, 05:10 PM

I plan to use a rubber grommet thru the hole or a plastic bushing that you would insulate a metal electrical box with. We think alike.
TD

Gordon92026 · 12-03-2023, 08:10 PM

Quote:

Originally Posted by creativepart

I looked up your 2017 Sunstar LX 37F's wiring diagram. I don't know if the panel layout is the same you have - because it might for for optional equipment that you don't have. But perhaps the concept is the same.

See how there is an Inverter Subpanel on the right? According to videos I've seen you simply physically move the circuit breaker on the Left that services that outlet behind the fridge to the Inverter Subpanel on the right.

DO NOT TRUST THIS INFO - I'm a hack that knows next to nothing. Just trying to put you on the right track.

I have one comment but kind of important. You say your inverter is 1000 W which is relatively low. Check the supply wire on the outgoing side of the AC circuit and determine if that wire is sufficient to carry the new load. If it’s too small the wire can get hot, posing a fire hazard.

TigeDuner · 12-03-2023, 10:21 PM

The fridge draws 1.2 amps AC and when we are driving, it should be the only draw on the inverter and this is when the fridge compressor decides to come on to the bring the fridge back to the set temp (not a constant draw).

I have to assume that Winnebago sized the wire based on the requirements of the inverter installed. If the draw is to much for the inverter, it will shutdown.

Since I will plug the fridge power cord into the outlet on the front of the inverter, there should not be an issue for that portion of the wiring.

Your comment is a good one, but I think Winnebago has it covered.
TD

l1v3fr33ord1 · 12-04-2023, 04:15 AM

TD-

When I removed the absorption fridge I was left with the 1-1/4-inch square hole that Monaco used to pass the copper gas line from under the sink into the fridge compartment. That hole was perfect for the 120V cord pass-through from the inverter.

As the plug was larger than the cord, that left the cord loose in the hole, a pathway for mouse movement. I snapped a piece of convoluted tubing around the cord, then filled the hole with Scotch-Brite stainless-steel scrubber (link here), keeping the cord in the rough center of the hole. Secure, easy to remove if needed, fairly resistant to airflow, and mouse-proof.

TigeDuner · 12-04-2023, 06:50 AM

Sounds like a good idea. I need to see if the tech that installed the residential unit left any holes in the compartment for piping that was removed as part of the propane fridge removal process. The RV facility that did the work for the previous owner (and where I bought the RV from) appears to have done a nice job sealing up the area and painting everything black. My only access is thru the existing fridge vent panel on the exterior of the RV, which is pretty limited.
Mice in our desert location are always a concern and fortunately Winnebago does a great job of sealing and foaming openings from the exterior. Thanks for the tip on the scotch brite idea.
TD