Providing DC Power to Engel Refrigerator

[GeorgeRa]

Originally Posted by avanti

I agree: both of my vans have had "master shutoff" switches. I would never consider not having one. Mine is set up like George's, with the solar, the battery meter and the Trik-L-Start the only items not disconnected when the van is "off". One flip of a switch and the van is in a known state. Saves a huge amount of thinking and no doubt many errors.

Battery meter would be nice to have on a separate switch, unfortunately my Magnum ME-ARC is powered by the Magnum Charger/Inverter.

[booster]

I agree with the others on a master disconnect. I added one to our 07 Roadtrek as it didn't come with one. Only thing that doesn't disconnect is the solar controller as if it is disconnected with the panels in the sun you can get big voltage spikes to any connected devices and the controller itself. I can disconnect it by pulling it's fuse, but only after shutting off the added solar panel switch.

[rvsprinterguy]

All's well with the fridge running on either AC or DC during test runs this past week.

I've purchased a relay to control power to the Engel with the original wiring to be used to trigger the relay and another pair, directly connected to the battery actually powering the refrigerator.

I haven't installed the relay yet, because I am jealous of the current required to energize it. I'm constrained by battery capacity already.

The installation of the Engel was easy. It's a SR48 Front Opening unit that is shorter and narrower than the Norcold it replaced. Its interior volume is therefore somewhat less, but is still sufficient for our needs.

I had to add a shelf for the fridge to sit on and frame in the sides a bit to provide a place to drive the screws holding it in place.

I ended up with a nice new storage area below, to which I added a wall in the back. Next step is to fabricate a door to install so I can put stuff there without worrying about it coming out while driving.

I used bubble-wrap-like material to seal the area behind the refrigerator and am contemplating adding some kind of barrier to the insides of the two plastic vents needed for the Norcold's operation.

One annoying thing was that the Power Converter developed a sympathetic rattle when the Engel compressor was running. I had to dig pretty deep into the high-voltage side to locate and dampen the rattle, which is now gone. This was accomplished with the power off, wearing gloves and poking around with non-conductive stick as I (gently) pounded on the unit listening for the rattle. I'm extra cautious around big capacitors.

[GeorgeRa]

Originally Posted by rvsprinterguy

................

I've purchased a relay to control power to the Engel with the original wiring to be used to trigger the relay and another pair, directly connected to the battery actually powering the refrigerator.

...............

There are bistable relays require energy to switch states only but not to run. https://www.delcity.net/store/Latchi...waAuNZEALw_wcB

Why relay? I am not clear.

[rvsprinterguy]

Thanks for the tip. A "latching" relay would be perfect.

Why a relay at all? To comply with Engel's directions to power the refrigerator directly from the battery, which I don't want to do because I lose the ability to shut off all DC loads from the master switch.

[GeorgeRa]

Originally Posted by rvsprinterguy

Thanks for the tip. A "latching" relay would be perfect.

Why a relay at all? To comply with Engel's directions to power the refrigerator directly from the battery, which I don't want to do because I lose the ability to shut off all DC loads from the master switch.

Adding a relay is not direct, or almost as direct as going from battery > main disconnect > CB/Fuse > Engel. I would calculate voltage drop at the fridge in your wiring and check if you get 12VDC during rush current / compressor start. If you are getting less improve the wiring. I would say that majority of commercial or DIY wiring follows this circuit:
Battery > Main Disconnect > Distribution Panel/CBs/Fuses > Switch (I use CB as a switch) > Fridge, just make sure you have 12VDC at the destination during high draw.

[proeddie]

I've had the Engel MR40 marine version (plastic case instead of metal) in my DIY campervan for about 6 years now. I got it right after MsNomer recommended Engel to me!

I ran a lighter socket to the back corner of the van where the Engel is. The power cord supplied by Engel says "do not cut the cig lighter plug off and direct wire" - so I didn't!

The socket it plugs into is wired with about 20' of #12 wire to a fuse panel and then on to my batteries. The batteries are also connected to the same power converter mentioned above. The fridge acts and runs the same whether the converter is on or off. In a DC power supply that's connected to a battery, the battery acts like a big capacitor and smoothes any AC ripple that may be in the power converter DC.

It auto switches to AC when I connect to shore power.

Works great... lots of cooling for very little power!

I can't see what a relay would add to the hookup...it's not needed.

[rvsprinterguy]

I've connected my Engel's DC input to the wires that formerly powered the original Norcold. Its AC power cord is plugged into the outlet also formerly used by the Norcold.

The refrigerator is working just fine and switches between AC and DC without any hiccups. It's really nice to have rock-solid temperature control.

I've taken advantage of the smaller height of the Engel and framed in a useful cabinet space below it, adding a door with self-closing hinges and a pull that matches the originals. Building a shaker-style cabinet door without the proper tools is an adventure, and I have a profound appreciation for the quality of the finish work done at the factory (mine looks home-made).