12 volt fridge qiestions

woodster · Feb 13, 2015

not sure what kind of refer you have but i have a weaco that runs on 12vdc ..when at the dock it runs of 120vac through a device that supplies 12vdc to the compressor when turned to 120vac..and when it runs off 12vdc switched from 120vac to 12vdc at the control panel if you have put something in the box it takes a while for it to cool down so it can cycle on and off...i put bottle water in the freezer part and let them freeze ...you have to have them full of contents to make them work properly ...try that and see if it starts to cycle on an off after a the water freezes good and hard

centerline · Feb 13, 2015

DougM said:
This is just a curiosity thing. My boat has a refrigerator that has for all intents and purposes never been put to use. I just have not needed it.
When I did start it up new, probably back in 2005, the compressor ran 24/7 . I presumed it was low on refrigerant but could not find a fitting anywhere that could be used to recharge it. Are these things supposed to run constantly? If not, and are in fact low on refrigerant, how can they be recharged?

Second question, regarding operation whole on shore power: has anybody considered a means of switching away from the 12 volt batteries to shore power and a separate Dc power supply exclusively for the refrigerator? It seems like the refrigerator would be a battery hog, and that would be a way to at least keep the beer cold.

I can only comment on the second part of your post....
If its a 12 volt unit, why would you want to purchase a converter specifically to run rhe 12v unit on ac power, when you "should" aleady have a battery charger onboard the does this for the batteries that you are worried about depleting?....

if you dont have a dedicated charger onboard, and you have 120v available, get one and use it. A GOOD one...

Capt jgw · Feb 13, 2015

Shouldn't run all the time unless its really, really hot out. Did it get cold? There's probably not a recharge port, I suppose a refrigeration mechanic could put one in but that sounds pretty expensive. Probably more cost effective to replace it. Is it a stand alone fridge or an ice box conversion? Some of the stand alones have automatic switching from a/c to d/c. You can probably get one from an RV store much cheaper than marine. Won't stand up to salt environment as long but of it's cheap enough that may be a better deal. I'm in fresh water so I always check the RV stuff first.

Ron20324 · Feb 13, 2015

No, it should not run full time. I assume you turned the thermostat fully in both directions several times to break through any corrosion? As the saying goes, you can use something and wear it out, or you can let it sit and it will rot . Rubber seals dry up from non-use.

In the slip, if I leave the fridge running, I don't trust the solar on a cloudy day to keep the batteries up, so I turn on the Xantrex charger set to the contant 13.2 volt setting. There have been several previous posts about installing a shore powered 12-volt supply. I suppose a search will turn these up.

In the slip or anchored out, I found by either leaving the cabinet door open or just lifting it off it's hinge helps to let the heat get away from the compressor. Chuck M put in a nice duct from the compressor fan to expell heat from the cabinet.

Chris Patterson · Feb 13, 2015

If it was of concern enough, I would simply use a high enough amp power supply, put a DPDT switch on it and rock. Incredibly simple..

Sandy Stone · Feb 13, 2015

I think if your charger maintains a system voltage above what a fully charged battery can supply (say above 12.7 or 12.8 volts, and it should) then the refrigerator is really running off the charger, not the batteries. In other words, the charger will increase its amp output to compensate for the load the fridge puts on the system.
Away from the dock, I like to put a bag of ice in the box. The ice helps the compressor keep the box cold, therefore less load on the batteries, and the compressor helps the ice last longer. They sort of share the cooling load.

seadaddler · Feb 13, 2015

12volt

I said the same thing why run 12 volt and use my batteries at the dock
with shore power so I added a converter $$$$$$$$$$$ big mistake as it
went bad one year of install and think it was a surge at the dock that blew it
and relay on ref.
I have been using 12 volt's and everything works fine and I have solar panels to keep the batteries up away from shore power.
No it should not run 24/7 so maybe the thermostat is too high or not working
properly but try different adjustments with a little temp gauge to see what's going on.
Nick

kloudie1 · Feb 13, 2015

This is what the service guy might install if it has low refrigerant:
http://www.zoro.com/i/G3756356/?utm...hopping_Feed&gclid=CNzO85Og38MCFZSKaQodsjoAdA

Check to see if it is the fan only, or compressor only or both running 24/7. Is it getting cold or cool or nothing is the real question..

Bill Murray · Feb 13, 2015

Nova Cool (http://www.novakool.com/index.htm) markets an AC/DC converter for their refrig conversion units. I have this on my installation and it does exactly what you are hoping to accomplish.

gray125 · Feb 13, 2015

Two reasons you may want to run the refrigerator from a dedicated power supply when plugged into shore power.
1. Battery charger may not be sized to charge batteries and run refrigerator that cycles on and off.
2. Smart charger can be confused by the cycling on and off of refrigerator.

There are power supplies that automatically switch over to battery when they detect that AC is off.

Ukeluthier · Feb 13, 2015

Umm, perhaps some input from a EE is in order here.

As long as your battery charger is capable of supplying enough current that its output does not drop below about 12.2 volts when the fridge compressor is running, the fridge is running off the charger, not the battery bank. The batteries will not be charging if the voltage drops that low, but the batteries will not be depleted either.

As to whether a smart charger would be "confused," that depends on exactly how a particular charger operates.

centerline · Feb 13, 2015

DougM said:
I just don't think it makes sense to use the batteries to run the fridge when the charger and the batteries could be bypassed, since shore power is readily available at the dock. I have a good charger and I maintain my batteries. I just don't want to rely on batteries for days at a time when docked, especially if it turns out that the thing is running constantly by design.

a battery charger is simply a converter... it is functionally the same as the converter you will need to run the fridge, with the exception that the power output of the charger is more highly regulated and is a better refined unit. BUT... for long term use as a power supply, it DOES need a battery hooked up to act as a buffer.

and the batteries could actually benefit by being used, rather than setting dormant.
any charger over about 6amps will run the fridge and maintain the batteries without worry.

the only thing what you propose to do can offer that you dont already have is, when you unplug the shorepower cord when you leave the dock, the fridge will be DEAD.... you wont have to worry about it running down the batts while sailing because you have forgotten to shut off the switch.
if you were on a long motor crossing/cruise, the fridge would have to be wired back in to the boat system, IF you wanted it to remain working during the time you are producing 12v power... hopefully you can remember to disconnect it as soon as you shut the engine down

.

if your worried that the charger might ever stop working and cause the batteries to discharge while plugged in, then you could easily install a low voltage cutout switch, so when the batteries get to a certain discharge level, the draw source will be disconnected... and this device will also work to protect the battery voltage when the shorepower cord is not plugged in...

Im just offering the facts in an attempt to save you some money when you already have it connected the best possible way... providing the rest of the electrical system is normal and hasnt had a bunch of other unnecessary devices wired into it already

woodster · Feb 13, 2015

this is the power supply that came with my fridge and i like its features as when you lose 12vdc power it auto switches to 120vac to keep on running the refer.... it either works on house 12 bank or 120vac if there is no 12vdc available

http://www.seamarknunn.com/acatalog...-100-240v-power-supply-2097.html#.VN47lubF-So

jsalley · Feb 13, 2015

woodster said:
this is the power supply that came with my fridge and i like its features as when you lose 12vdc power it auto switches to 120vac to keep on running the refer.... it either works on house 12 bank or 120vac if there is no 12vdc available http://www.seamarknunn.com/acatalog/waeco-coolpower-mps-35-100-240v-power-supply-2097.html#.VN47lubF-So

They sell this at Defender (with a North American plug!). My 2006 Catalina 309 came with one from the factory - had to replace it twice in 3 years. After the third failure, I got one made by Indel/Isotherm (also at Defender) - more $, but far more robust and still working when I sold the boat last year.

Hello Below · Feb 13, 2015

DougM said:
This is just a curiosity thing. My boat has a refrigerator that has for all intents and purposes never been put to use. I just have not needed it.
When I did start it up new, probably back in 2005, the compressor ran 24/7 . I presumed it was low on refrigerant but could not find a fitting anywhere that could be used to recharge it. Are these things supposed to run constantly? If not, and are in fact low on refrigerant, how can they be recharged?

Second question, regarding operation whole on shore power: has anybody considered a means of switching away from the 12 volt batteries to shore power and a separate Dc power supply exclusively for the refrigerator? It seems like the refrigerator would be a battery hog, and that would be a way to at least keep the beer cold.

I had similar issues when I took delivery of my new then 2012 Hunter. The Dometic front loading fridge was capable of running on both AC and DC. If there was shore power then it was supposed to automatically switch to the 120v through its convert to supply the necessary 12V to the compressor. It did not. When I pulled out the fridge to inspect, I saw that the AC power cord was not plugged in. That corrected that problem. Several months later, I noticed the compressor was running full time 24/7. It did manage to hold the internal temp but when away from shore power it ate through the amp hours like crazy. I took the boat back to the dealer and the service manager in conjunction with the local Dometic dealer replaced the unit. All is well with the fridge after nearly 3 years of full time operation.

As an aside, I normally switch the battery switch (1-Both-2) to off when I am plugged into shore power and I am not aboard. All the safety devices including bilge pump, CO detectors, AM/FM radio to keep the stations and time in memory are directly connected through fuses to the batteries (the way it came). So in this case the fridge would also shut down if it were not also feed by AC.

Benny17441 · Feb 13, 2015

You do not indicate if the unit is running now but with the time elapsed with no use or maintenance I think the proper call would be to have a marine refrigeration tech look at the unit and suggest the best course of action. If it is simple like adding refrigerant or replacing a faulty thermostat he could do that in the same visit. If other components need replacing you may ask for his estimate and then decide if you want to fix it or ditch it. In any instance for the cost of a service call you could have the answer to your question. Regarding operating the refrigerator on shorepower it is perfectly adequate to run it off the batteries while letting the battery charger supply the power. Many run theirs this way 24/7. When precooling a refrigerator always do it while connected to shore power and help it along by introducing some frozen and cold items into it. A refrigerator works most efficiently when full and poorly when empty.

Gunni · Feb 13, 2015

Doug, given the age I suspect you have one of the 3-phase (Danfoss?) compressor Adler Barbour units. It draws about 5 amps when running, and you may have a small pancake fan and controller that takes that up to about 8 amps.

We leave ours on all season long, plugged up to shore power. It does not run all the time. Cold beer, and food for 12 years. These are amazing pieces of technology.

gettinthere · Feb 14, 2015

Our 12 volt Seafrost refer is powered thru the house bank. The house bank receives charge from the engine alt or the solar panels or the wind gen or the zantrax truecharge 40 charger that can be powered by shorepower or the genset.

As fulltime cruisers, we anchor out for long periods, we motor for long periods, we sail for long periods, we tie to shore power at the dock for long periods. Powering the refer with whatever power source we have is seamless.

Its been that way for us since 2008. I dont see any need whatsoever for a dedicated 110v power supply.

As for why it runs all the time, a GOOD refer tech can help. Beware, there are a lot of pretend refer techs out there. You can also search out Richard Kollmanns website and ask him. And you could buy his book on refer service.