Compressor Fridge Question

[GallenH]

Wondering....and I think this may have been referenced somewhere...but when considering a compfridge, is there an advantage to getting a DC/AC model over the DC model?

[Knit]

Originally Posted by GallenH

Wondering....and I think this may have been referenced somewhere...but when considering a compfridge, is there an advantage to getting a DC/AC model over the DC model?

In my opinion, yes. AC will then be used when RV is on shore power either camping or in storage. But when on DC, you likely get the lowest DC amps as well.

[GeorgeRa]

I have AC/DC Isotherm fridge and use AC occasionally. AC is wired to one CB on the main panel allowing me to have everything off except the fridge. If I had DC only, I would have to use DC side with battery charger on, which is OK but I preferred to have in storage most of equipment off if possible.

I installed Isotherm Smart Energy Controller, electronic thermostat with some smarts. It can be used on any Danfoss BD35F compressors but installations are plug and play on DC only models and AC/DC units require some wiring modifications. I like a lot my Smart Energy Controller, it is quieter – no more clicking on/off noise and mostly runs the compressor at lower RPM. The unit slightly lowers the temperature set-point during voltage presence.

https://www.youtube.com/watch?v=F2hAWqFVkUI

[InterBlog]

It depends on your system configuration. We set ours up to run 100% off 12 volt. On those rare occasions when we are plugged in, the battery can be electively be charged by the shore power, so there's no harm in keeping the fridge on the battery.

[avanti]

As I see it, any possible argument in favor of the AC option involves situations in which you desire to run the AC during storage periods. If you are camping on shore power, you are presumably running your converter/charger anyway and the extra power brick inside the fridge is redundant and inefficient. But, during storage, having AC/DC lets you run the fridge with the charger off, as George says. I can think of no other case in which running on AC makes any sense.

[booster]

We also run ours on DC only as they are native DC devices anyway and whenever we are on shore power the charger is on like most others have mentioned.


The exception might be those that have lithium setups with full cutoff chargers. They might benefit from the battery use when on shore power by using AC.


I will add a very slight modification to what GeorgeRa mentioned about the Isotherm Smart thermostat/controllers.


They can't be installed on all Isotherm frigs, particularly the older ones. When I looked at getting one for ours, the compressor model number was not covered. This is likely not much issue because there aren't many of the older ones around, though, as ours is maybe 8 years old now.

[GeorgeRa]

When I was buying my Isotherm fridge in 2013, I didn’t know that Isotherm Smart Controller was designed for DC units, the blue box connector pattern matches Danfoss DC controller pattern and no wiring is required, just unplug the wiring harness plug from the Danfoss controller and plug the blue box in between main harness and the Danfoss. In my case I had to wire standalone blue Smart Energy Controller box. Have I known that I would forgo the AC option.

[booster]

Originally Posted by GeorgeRa

When I was buying my Isotherm fridge in 2013, I didn’t know that Isotherm Smart Controller was designed for DC units, the blue box connector pattern matches Danfoss DC controller pattern and no wiring is required, just unplug the wiring harness plug from the Danfoss controller and plug the blue box in between main harness and the Danfoss. In my case I had to wire standalone blue Smart Energy Controller box. Have I known that I would forgo the AC option.

I will have to look again at exactly what the deal was. I am quite sure it is DC only, but when I went to look at the controllers it said they were only compatible with some compressor models and outs was not one of them. Need to check that out again.


On edit: This is the latest and greatest controller that I wanted to get. Liked the functions and small external display and setting. Or BD35F is a 101N0210 or 101N0220 which aren't in the usable range with this controller. The one George got may be OK, but I haven't been able to confirm that yet.

[tgregg]

Originally Posted by booster

I will have to look again at exactly what the deal was. I am quite sure it is DC only, but when I went to look at the controllers it said they were only compatible with some compressor models and outs was not one of them. Need to check that out again.


On edit: This is the latest and greatest controller that I wanted to get. Liked the functions and small external display and setting. Or BD35F is a 101N0210 or 101N0220 which aren't in the usable range with this controller. The only George got may be OK, but I haven't been able to confirm that yet.

We wanted the iTC digital display / thermostat unit and our compressor wasn't compatible as well.

We were able to purchase a compatible 101N0212 compressor controller from Appliance Parts Co and the swap is very easy if you have access to the compressor.

Many benefits: Ability to see / change the temperature without opening the refrigerator, soft compressor start, slower compressor speed, eimination of the mechanical thermostat 'click' on/off.

[GeorgeRa]

Originally Posted by booster

I will have to look again at exactly what the deal was. I am quite sure it is DC only, but when I went to look at the controllers it said they were only compatible with some compressor models and outs was not one of them. Need to check that out again.


On edit: This is the latest and greatest controller that I wanted to get. Liked the functions and small external display and setting. Or BD35F is a 101N0210 or 101N0220 which aren't in the usable range with this controller. The only George got may be OK, but I haven't been able to confirm that yet.

This is nice, I am going to look into it.

[avanti]

Originally Posted by tgregg

We were able to purchase a compatible 101N0212 compressor controller from Appliance Parts Co and the swap is very easy if you have access to the compressor.

I do like the slick digital panel. Starts to get a little pricy, though, if you also have to replace the controller.

[booster]

Originally Posted by avanti

I do like the slick digital panel. Starts to get a little pricy, though, if you also have to replace the controller.

That is pretty much the same conclusion I came to. Nice product but $300+ into a nearly 10 year old frig doesn't look like a smart investment.


if ours dies, we would get the newer model of the same frig, but with the ITC controller.

[GallenH]

Fantastic discussion. Exactly the info I was looking for. Thanks. I'm curious as to why people run the fridge in storage. On my evap, it's just off. Is it to prolong live?

Anyways I still have an ancient Dometic 3-way......22 yrs old....model 2351. Eventually I plan to dedicate a compressor fridge to a lithium batt and when my AGM LifeLine goes probably shift to all lithium. That's, of course, in the future but how far depends on when the last breath of life comes from the old Dometic. Could be tomorrow.

So all of your comments are extremely valuable to my planning. Thx.

Glenn

[GeorgeRa]

Originally Posted by GallenH

……………………… I'm curious as to why people run the fridge in storage. On my evap, it's just off. Is it to prolong live? ………………………….

We keep fridge running during short storage (week – month) for convenience of packing and unpacking for next trip. For long storage everything is off. If DC is on the fridge is running on DC.

Would I get AC/DC again, I don’t know - would need to evaluate it again. Electronic intelligent temperature control would be much more important in deciding a new fridge. Electromechanical capillary thermostats are ancient, are noisy, run compressors in single speed bang-bang style control.

[GallenH]

Originally Posted by GeorgeRa

We keep fridge running during short storage (week – month) for convenience of packing and unpacking for next trip. For long storage everything is off. If DC is on the fridge is running on DC.

Makes perfect sense. And I keep forgetting: most of you can/do store at home. Because of HOA rules I have to store in a storage facility....or build a
bigger/taller garage.

best

[MsNomer]

My van doesn’t rest for more than a week or so year-round, so my Engel has run continuously for nearly 4 years. Engel says not to run it on an inverter, so it has a dedicated AC outlet direct to shore for the rare times it plugs in.

[GeorgeRa]

Originally Posted by MsNomer

My van doesn’t rest for more than a week or so year-round, so my Engel has run continuously for nearly 4 years. Engel says not to run it on an inverter, so it has a dedicated AC outlet direct to shore for the rare times it plugs in.

I wouldn’t be surprised if Engels folks are playing safe and don’t differentiate between full sine wave versus others pseudo sine square wave ones.

[eric1514]

I use this

Dwyer TS2-30

I inserted the probe through the same hole the factory probe inters and connected the thermostat to the controller in the same way the factory one was. I left all the old stuff in place.

And I might add this, but so far just adding a 277ohm resistor has done wonders during the hot summer.

Merlin II

[MsNomer]

Originally Posted by GeorgeRa

I wouldn’t be surprised if Engels folks are playing safe and don’t differentiate between full sine wave versus others pseudo sine square wave ones.

You may well be correct. However, it was not difficult to do as they say. Better safe than sorry, especially given that our Xantrex is not exactly top of the line.

[Phoebe3]

Our NovaKool was originally AC/DC but it had problems when switching power sources while running, resulting in unexpected shut-off. NovaKool had a recall that involved changing the controller from AC/DC to DC only.