Powering a 12 Volt refrigerator via USB port

[rich2468]

Hi Rob, Magnadyne is the company who makes the 4 port USB wall outlet you have pictured. If you don't mind sacrificing a couple of the USB ports to gain a 12-Volt outlet, you could replace the 4 port USB with their wall outlet version with two USB ports and a 12-Volt power outlet.
(but read further down for a better solution)

The Magnadyne WCP-12V has both USB Ports and a 12-Volt power outlet. It's available via Amazon or directly from Magnadyne.

I've replaced the 4 USB Port (Magnadyne WCP-USB) with the Magnadyne WCP-12V in my TrailManorand and found that my 12-volt portable fridge does draw a small enough amount of Amps to run from the 12-Volt port in the WCP-12.

Despite the WCP-12V powering my 12-Volt portable fridge, it turns out that an automotive 12-Volt port outlet is not the best electrical connection for something that's critical and also likely to move. Going over abrupt sections of dips in western highways (and even speed bumps) caused my 12-Volt fridge's connection to be unpredictable. I'd suggest only using one for a 12-Volt TV or fan.

Since returning from a 36 day trip suffering through the poor connection between my TrailManor's 12-Volt automotive style outlet and my 12-Volt fridge's power plug, I've found the better way to handle that connection is installing what's frequently called an "ARB socket".

The ARB socket is threaded and keyed for polarity. Most 12-Volt refrigerator plugs can use an ARB socket by simply unscrewing the automotive plug end revealing two electrical pins.
(see the attached photo link)



I've bought (but not yet instead installed) the: ARB 10900028 (which just includes the outlet). I should have it installed before a trip in late Feb. to the Everglades (I'll post a follow follow up afterwards with how it works out).

ARB also sells part# 10900027 which is a whole kit (with outlet and 20 feet of wiring). Additionally; the ARB outlet which is shown in the above photo can be removed from that external enclosure so that it can be surface mounted.

[Rob Culver]

Originally Posted by Bill

Just FYI, I find that some of those corner knobs have to be turned to vertical to come off, and some have to be turned horizontal. Annoying, isn't it? I end up turning one button at time, 90* from wherever it starts, and pulling gently on the corner of the panel to see if it is loose.

I'm not sure if cutting a hole in the side of the cubby, and bringing wires to the under-sink area, will help you a lot. Yfou still have to connect your new wires to something, and the under-sink area has poorer access and smaller wires than behind the refrig.

Another idea. I rely on our 3-way frig, but I don't power it up on the road. It is actually a pretty good cooler. Assuming it is nice and cold in the morning, I just turn it off while I travel, and food is still cold/frozen after several hours. In your case, the advantage of doing that would be that you could connect new wires (for the compressor refrig) directly to the existing connections on the back of the 3 way frig. Access to those connections is easy. My Dometic 2354 is shown below, and you can see the arrow for the 12-volt terminal block at bottom center. If you have a Norcold, 3-way refrig, it is similar.

Of course, once you are in a campground, you will want to run both refrigerators, and as Shane suggested earlier, the 12-volt fuse may not carry as many amps as you need. The answer would be to run the 3-way frig on either 120VAC if you have it, or propane.

Bill

Hi Bill,
That would be great if you had a picture of where to connect to behind the vent. I just added a couple of pictures of what mine looks like. I've got a dometic also. Comparing that to your diagram, I think I even see the 12 volt terminal block from your diagram. When you look at my foto, the left side of that is a wall which is the same wall as I show in my foto of the inside of the unit which has the three outlets. It's a pretty good location to bring the 12 volts out to since that's probably where I'd put the DC refrigerator. I can even see the back side of the three outlets from the inside of the Vent area.

I'm not too concerned about picking up 12 volts from the DC refrigerator since I'd never use the DC mode anyway.

[Rob Culver]

Originally Posted by rich2468

Hi Rob, Magnadyne is the company who makes the 4 port USB wall outlet you have pictured. If you don't mind sacrificing a couple of the USB ports to gain a 12-Volt outlet, you could replace the 4 port USB with their wall outlet version with two USB ports and a 12-Volt power outlet.
(but read further down for a better solution)

The Magnadyne WCP-12V has both USB Ports and a 12-Volt power outlet. It's available via Amazon or directly from Magnadyne.

I've replaced the 4 USB Port (Magnadyne WCP-USB) with the Magnadyne WCP-12V in my TrailManorand and found that my 12-volt portable fridge does draw a small enough amount of Amps to run from the 12-Volt port in the WCP-12.

Despite the WCP-12V powering my 12-Volt portable fridge, it turns out that an automotive 12-Volt port outlet is not the best electrical connection for something that's critical and also likely to move. Going over abrupt sections of dips in western highways (and even speed bumps) caused my 12-Volt fridge's connection to be unpredictable. I'd suggest only using one for a 12-Volt TV or fan.

Since returning from a 36 day trip suffering through the poor connection between my TrailManor's 12-Volt automotive style outlet and my 12-Volt fridge's power plug, I've found the better way to handle that connection is installing what's frequently called an "ARB socket".

The ARB socket is threaded and keyed for polarity. Most 12-Volt refrigerator plugs can use an ARB socket by simply unscrewing the automotive plug end revealing two electrical pins.
(see the attached photo link)



I've bought (but not yet instead installed) the: ARB 10900028 (which just includes the outlet). I should have it installed before a trip in late Feb. to the Everglades (I'll post a follow follow up afterwards with how it works out).

ARB also sells part# 10900027 which is a whole kit (with outlet and 20 feet of wiring). Additionally; the ARB outlet which is shown in the above photo can be removed from that external enclosure so that it can be surface mounted.

Very interesting Rich,
I'm sure I'll have a few questions about this as I begin to study it. For starters though, can you tell me the brand / model of your refrigerator and any other info you might have like how many cubic feet it is and how many amps it draws?

[Bill]

I've got a dometic also. Comparing that to your diagram, I think I even see the 12 volt terminal block from your diagram.

Yes, I believe you have spotted it in the first photo. Near the right hand edge of the picture, about halfway between top and bottom, the four (two pairs) white nylon tubes.

One thing confuses me, though. It looks like there are two wires going into the bottom of the block of four, black on the left, and white on the right. I would assume that the black would be +12v, and the white would be ground. But it appears that coming out of the top of the block, there are two red wires on the left (which also suggests +12 v), and two black wires on the right. In other words, it looks like the white wire below is connected to the two black wires above. That doesn't seem right. Perhaps it is just that the angle of the photo is misleading me. Perhaps the white wire below doesn't actually go into the block, but is just passing under and behind it. But I would want to know for sure before I started making new connections.

Bill

[rich2468]

Rob, I have a Dometic CFX3-55IM which (in theory) should trip the 7.5 amp fuse on the 12 Volt circuit, but in practice I've never seen it pull much over 4 amps (at startup). The CFX3-55IM typically settles in and runs at around 1.1 amps/hr after starting. Those running amps were observed between 80 and 90 degrees ambient temperature with the CFX3-55IM fridge/ freezer running in freezer mode (below 20 degrees). The items inside the fridge/ freezer were put into a deep freeze while on household AC, so I'm sure that helped minimize any start up spikes while under DC mode.

I used the CFX3-55IM plugged into the Magnadyne WCP-12V which worked fine power wise, but the Dometic plug failed to maintain a reliable connection during a cross country trip. (Dometic confirmed that they knew this was a defect issue with their 12-Volt cord and sent me an updated/ warranty replacement cord mid-trip.)

The warranty replacement 12-volt cable significantly improved connectivity, but I still had a few disconnections (meaning that during fuel stops I still had to check via the Dometic bluetooth phone app to see that the CFX3-55IM was running). That's the main reason why I'm migrating to the ARB plug.

My TrailManor has the TV cable outlet to the right of the USB outlet (like yours shows in your picture). I also replaced my factory cable outlet with Magnadyne's WS-12V (which has both a TV coax plug and a 12-Volt outlet) with the intent of being able to use two 12-Volt appliances at a time at the front of the camper. Since both 12-Volt plugs share the same circuit that'd be possibly running a fan and a TV or a fan and a fridge, but never with a TV and a fridge.

That's the second reason pushing me to migrate to the ARB plug (on its own circuit).


Last minute update: It appears that Dometic is selling their own combo 12-Volt plug/ ARB-style plug kit. If I'd have seen this prior to my Magnadyne outlet upgrades, I'd have likely left those stock and just run a dedicated power line to the Dometic DC plugs (their setup is rated to handle 15 amps).

[Rob Culver]

Originally Posted by rich2468

I used the CFX3-55IM plugged into the Magnadyne WCP-12V which worked fine power wise, but the Dometic plug failed to maintain a reliable connection during a cross country trip. (Dometic confirmed that they knew this was a defect issue with their 12-Volt cord and sent me an updated/ warranty replacement cord mid-trip.)

The warranty replacement 12-volt cable significantly improved connectivity, but I still had a few disconnections (meaning that during fuel stops I still had to check via the Dometic bluetooth phone app to see that the CFX3-55IM was running). That's the main reason why I'm migrating to the ARB plug.

My TrailManor has the TV cable outlet to the right of the USB outlet (like yours shows in your picture). I also replaced my factory cable outlet with Magnadyne's WS-12V (which has both a TV coax plug and a 12-Volt outlet) with the intent of being able to use two 12-Volt appliances at a time at the front of the camper. Since both 12-Volt plugs share the same circuit that'd be possibly running a fan and a TV or a fan and a fridge, but never with a TV and a fridge.

That's the second reason pushing me to migrate to the ARB plug (on its own circuit).


Last minute update: It appears that Dometic is selling their own combo 12-Volt plug/ ARB-style plug kit. If I'd have seen this prior to my Magnadyne outlet upgrades, I'd have likely left those stock and just run a dedicated power line to the Dometic DC plugs (their setup is rated to handle 15 amps).

Rich,
Thanks for the comprehensive info. Was it fairly simple to rewire the original 4 USB connector to the Magadyne WS-12V? And just to clarify. Is your plan now to cut out a new hole near the Magnadyne WS-12V outlet to wall mount the ARB 10900028? Would you then just take the 12 volt and ground wires from the Magadyne and attach them to the ARB?

[rich2468]

Replacing the Magadyne 4 USB plug outlet with the Magadyne WS-12V (2 USB/ 12-Volt automotive) outlet didn't take more than 10 minutes. Everything is the exact same size and the wiring behind the outlet (inside the TrailManor's refrigerator) simply plugged right into to the Magadyne WS-12V. It could not have been easier.

In wiring the ARB outlet, I plan to run a new dedicated line (to the TrailManor's) power center. That will eliminate the capacity contstraint concerns which I have. I've set my TrailManor to have as much boondocking flexibility as is feasible (given the size/ design) and feel the need to be able to run three 12-volt powered appliances (or two higher amperage ones) at any given time at the front of the TM lines up with the rest of my work in doing that.

[Rob Culver]

Originally Posted by rich2468

Replacing the Magadyne 4 USB plug outlet with the Magadyne WS-12V (2 USB/ 12-Volt automotive) outlet didn't take more than 10 minutes. Everything is the exact same size and the wiring behind the outlet (inside the TrailManor's refrigerator) simply plugged right into to the Magadyne WS-12V. It could not have been easier.

In wiring the ARB outlet, I plan to run a new dedicated line (to the TrailManor's) power center. That will eliminate the capacity contstraint concerns which I have. I've set my TrailManor to have as much boondocking flexibility as is feasible (given the size/ design) and feel the need to be able to run three 12-volt powered appliances (or two higher amperage ones) at any given time at the front of the TM lines up with the rest of my work in doing that.

Question for you Rich on the Magadyne WS-12V. I noticed looking at the online information that it used a Variable Phone adapter socket (VPA) for the 12 volt. This looks alot like a cigarette lighter socket but they tell you specifically in the installation doc that it's not and don't use it with one. Does this mean that Dometic supplied you with a 12 volt connector plug and cable designed to plug in to that VPA socket? I see there are other brands of 12 volt refrigerator / coolers that look like they use the cigarette lighter and not the VPA to supply the 12 volts but it's hard to say because normally they only say that it will plug in to your cars cigarette lighter socket.

Also kind of wondering in the back of my mind if theres such a thing as an adapter which converts from the cigaretter lighter plug which presumably most refrigerator manufacturers would provide and a VPA plug.

[rich2468]

Rob, I'm near 100% sure VPA stands for Vehicle Power Adapter (and not Variable Power Adapter). A VPA plug can go into either automotive cigarette lighter sockets or ones specifically designated as a VPA.

The Dometic plug for my fridge is the same as as in the picture with the ARB socket (technically a VPA). I think the standards have changed to where everything we remotely identify as an automotive cigarette lighter is strictly considered a VPA as vehicles no longer come with the ability to accommodation the lighter piece. (For around the past 15 years)

The design was never intended to power 12-Volt accessories, but it grew into it by necessity and has been successful only because of the lack of something else better.

An "ARB" style plug is far superior. I'm sure that there's an engineering group designation, but I'm not aware of it.

[Rob Culver]

Originally Posted by rich2468

Rob, I'm near 100% sure VPA stands for Vehicle Power Adapter (and not Variable Power Adapter). A VPA plug can go into either automotive cigarette lighter sockets or ones specifically designated as a VPA.

The Dometic plug for my fridge is the same as as in the picture with the ARB socket (technically a VPA). I think the standards have changed to where everything we remotely identify as an automotive cigarette lighter is strictly considered a VPA as vehicles no longer come with the ability to accommodation the lighter piece. (For around the past 15 years)

The design was never intended to power 12-Volt accessories, but it grew into it by necessity and has been successful only because of the lack of something else better.

An "ARB" style plug is far superior. I'm sure that there's an engineering group designation, but I'm not aware of it.

Thanks Rich. Appreciate the clarification.