fridge - cooling only on batteries

Got to the boat a couple days ago after about 4 months away. Boat was at a very nice marina connected to shore power.
Upon opening the refrigerator I noticed that it was not cool at all.

Just as an experiment I tried running it off the 12 volt side and it cools perfectly.

Fridge is a 17 year old isotherm under counter unit.

Seems to me that it would make more sense for the fridge to work on 120v and NOT on 12v.

Any ideas on a simple fix, or is a replacement in my future? Since it has had a nice long life, I'm fine replacing if necessary. Any brands to stay away from?

Thanks as always.

Some boat refrigerators have 12 volt compressors and use a converter to run on 120 VAC.

If it runs fine on 12 volt then you need to replace the converter only.

If it was mine, I would run it from 12 VDC and have the battery charger replenish the battery and not waste money on a redundant converter.

My Seafreeze refrigerator was ordered to run on 12 VDC only - no converter.

The Isotherm, I believe, uses a Danfoss type rotary compressor and they last a very long time. The Danfoss compressor on our Seafreeze has been running for 19 years with no issues.

I concur with syjos.

I would agree with running it on 12 VDC for the future.

As it's 19 years old, I would start hunting for the replacement. It's a lot easier to shop and be objective when you food is still cold.

Ted

Our fridge runs 24/7/365, it is only 12 volt direct off the batteries and the charger looks after the batteries. This is what was suggested by the manufacturer.........

The 12 VDC Danfoss compressor will not suddenly quit. It will start making a little noise that will gradually get louder when it's ready to replace and the compressor may take longer to cool the frig. I've seen Danfoss compressors run 1 to 2 years after the noise starts.

If the compressor is not a genuine Danfoss, there are imitation or knockoff compressors that look just like a Danfoss, can't tell you what it's behavior will be in it's final stages.

The Danfoss compressor is a dependable compressor that will outlast most other compressors, especially more than the Norcold swing compressor which has a 7 to 10 year life before they get noisey and run continuously without cooling much.

I guess this means it is a native DC compressor with a converter to change incoming AC to DC? I really thought it would work in the opposite direction but this makes sense considering all boats have some sort of DC power.



And based upon this:
https://www.indelwebastomarine.com/fileadmin/webasto_files/documents/IndelWebastoMarine/Spareparts/cr130-drink-spare-parts.pdf , this is the replacement module:
http://www.isotherm-parts.com/isotherm-parts-department/electronic-modules-and-asu-controls/compressor-modules-for-isotherm-refrigerators/ac-dc-module-for-all-secop-danfoss-bd35-bd50-compressors


Not sure my boat is smart enough to run the fridge off of battery power if I'm away for a week without totally killing the batteries. I believe I had that happen at the dock a couple years back.

As long as the capacity and the voltage match, you do not have to buy an Isotherm compressor. I'm sure Isotherm buys the compressors and private labels them.

Talk to a Danfoss distributor or a marine refrigeration shop and they should have a replacement at less cost maybe than Isotherm. Dave at Seafreeze - seafreezeinc.com is a Washington State marine refrigeration specialist. You might not buy from him but he could refer someone in your area.

Is your compressor hard plumbed or does it have quick connectors? That will determine installation. My Danfoss is connected with quick connectors which allows me to replace my compressor with a pre charged compressor without pulling vacuum and refilling the refrigerant.

If no quick connectors, a refrigeration tech. will be required.

I would not do this but 120 VAC rotary compressors are about half the cost of 12 VDC compressors. The AC compressor will operate off the inverter but you will experience higher 12 volt usage because of the inverters conversion loss.

If I look at that model number, that "1" in the middle suggests to me that this is a DC-only unit, i.e.

1130 = Cruise 130 line
BA = Drink model (no freezer)
1 = DC-only

The text of the sticker also suggests to me that it is DC only, e.g. 12/24V.

So....if I had a wild guess, I'd guess that this is a DC-only unit to which Isotherm's optional AC/DC module (Part number: z999/561) was added. This module converts 120VAC power into 24VDC and, once wired in, automatically switches between the battery DC source and the 120VAC-derived 24VDC source, preferring the 120VAC-derived 24V, when available.

-- http://www.isotherm-parts.com/isoth...rols/ac-dc-converter/isotherm-ac-dc-converter
-- https://www.defender.com/product.jsp?id=825933
-- https://www.fisheriessupply.com/isotherm-ac-to-dc-power-converter-z999-561

This module will automatically convert AC power to 120V power and switch the unit from battery-based 12V to 24V derived from the AC source when AC is available.

So, my guess is...that the AC/DC module isn't working and needs to be fixed or replaced.

You could just order a new one. But, before doing that, I'd check the simple stuff. I'd see if there is a fuse on either or both sides of it. I'd check its connections at the terminal block, etc. I'd see if there is something internal that can be repaired. Etc.

bobbyp said:

Not sure my boat is smart enough to run the fridge off of battery power if I'm away for a week without totally killing the batteries. I believe I had that happen at the dock a couple years back.

Click to expand...

Don't you have a battery charger to keep the battery topped up?

syjos said:

Don't you have a battery charger to keep the battery topped up?

Click to expand...

I was at a marina that had electrical issues where being out of power for a few days wasn't something that was a very high priority. Learned not to keep anything perishable in the fridge.

gkesden said:

If I look at that model number, that "1" in the middle suggests to me that this is a DC-only unit, e.g.

1130 = Cruise 130 line
BA = Drink model (no freezer)
1 = DC-only

The text of the sticker also suggests to me that it is DC only, e.g. 12/24V.

So....if I had a wild guess, I'd guess that this is a DC-only to which Isotherm's optional AC/DC module (Part number: z999/561) was added. This module converts 120VAC power into 24VDC and, once wired in, automatically switches between the battery DC source and the 120VAC-derived 24VDC source, preferring the 120VAC-derived 24V, when available.

-- http://www.isotherm-parts.com/isoth...rols/ac-dc-converter/isotherm-ac-dc-converter
-- https://www.defender.com/product.jsp?id=825933
-- https://www.fisheriessupply.com/isotherm-ac-to-dc-power-converter-z999-561

This module will automatically convert AC power to 120V power and switch the unit from battery-based 12V to 24V derived from the AC source when AC is available.

So, my guess is...that the AC/DC module isn't working and needs to be fixed or replaced.

You could just order a new one. But, before doing that, I'd check the simple stuff. I'd see if there is a fuse on either or both sides of it. I'd check its connections at the terminal block, etc. I'd see if there is something internal that can be repaired. Etc.

Click to expand...

Thanks, I'll pull the refrigerator and see how it is wired up.

bobby.p,

I somehow missed the bottom of your post below that picture. If that is the AC/DC model (vs DC-only), it has that module built-in. And, I think you've hit the right part (but it looks DC-only with add on module to me).

Before I'd buy it, or the add-on version of the AC/DC module I noted, I'd do exactly as you suggest and pull the unit and look. If it is external, check the model number on the sticker. If it is internal -- do the same. There should still be a sticker on it. And, if not, look for one on the compressor to double check compatibility.

If all else fails, call them or the dealer for the right part number. With the model and serial number, they should be able to tell you which part for sure.

In any case, the unit, internally, is primarily a DC unit, and there is a module that does the AC->DC conversion and switching. This module is most likely the culprit and getting the right one is the only trick.

And, even then, a quick look and phone call isn't too much of a trick. You'll have to pull the unit to put it in anyway, so it is worth it to get the right part.

And since that is what you are doing...you seem to be on exactly the right path. Good luck!

bobbyp said:

I was at a marina that had electrical issues where being out of power for a few days wasn't something that was a very high priority. Learned not to keep anything perishable in the fridge.

Click to expand...

If your dock power goes out, so does the AC frig.

On DC, it will continue running, duration depends on size of battery bank and when AC comes back on.

syjos said:

If your dock power goes out, so does the AC frig.

On DC, it will continue running, duration depends on size of battery bank and when AC comes back on.

Click to expand...

That is exactly what happened, fridge switched to DC power and my batteries went down to an unrecoverable voltage. Marina was crappy in all ways except for the staff but has a fabulous location and a waiting list measured in years.

"I was at a marina that had electrical issues where being out of power for a few days wasn't something that was a very high priority."

Wait till winter knocks out the power , it can be weeks!

Sounds like 79th street marina?

bobbyp said:

That is exactly what happened, fridge switched to DC power and my batteries went down to an unrecoverable voltage. Marina was crappy in all ways except for the staff but has a fabulous location and a waiting list measured in years.

Click to expand...

One of the positives of an AC only refrigerator running through an inverter is that when you lose dock power it maintains the refrigerator through the inverter off the batteries; when the batteries go below a minimum voltage (user setable on better units) the inverter shuts off, keeping the batteries from reaching an unrecoverable voltage.

Ted

gkesden said:

So, my guess is...that the AC/DC module isn't working and needs to be fixed or replaced.

Click to expand...

I concur. We had a unit like that in a previous boat, it would randomly refuse to keep chilled when on shore power. As in, it'd sense shore power AC and 'switch over' to using it... but not actually keep cold. If shore power was disconnected, it'd pull from 12v and chill properly.

But this is problematic in that without shore power (like when unattended during the week) that would lead to running down the house battery bank, which was woefully undersized for our needs anyway.

A refrigerant leak developed and while it was out for that I had the board replaced and that seemed to solve the problem. After that we kept the 12v breaker to it OFF most of the time, to avoid battery issues. If we didn't have shore power or generator AC we treated it more like a cooler, and limited how often we opened it.

I never did get around to installing a voltage cut-off switch. We just learned to live with it instead.

"One of the positives of an AC only refrigerator running through an inverter is that when you lose dock power it maintains the refrigerator through the inverter off the batteries; when the batteries go below a minimum voltage (user setable on better units) the inverter shuts off, keeping the batteries from reaching an unrecoverable voltage. "


YES YES YES!

FF said:

"One of the positives of an AC only refrigerator running through an inverter is that when you lose dock power it maintains the refrigerator through the inverter off the batteries; when the batteries go below a minimum voltage (user setable on better units) the inverter shuts off, keeping the batteries from reaching an unrecoverable voltage. "


YES YES YES!

Click to expand...

Exactly the reason we keep the 12v fridge breaker off when leaving the boat. Also FF, you are correct, that was the 79th Street Boat Basin - great staff, location is 5 minute walk home but the boat gets constantly pounded even with lots of big fenders and sometimes dangerous just walking on the floating docks when the waves come in.

I found a troubleshooting document in my papers, tested it and found the converter is only outputting around 10v when running in shore power/generator mode so will be ordering one of these for next time we are at the boat.

http://www.isotherm-parts.com/isotherm-parts-department/electronic-modules-and-asu-controls/ac-dc-converter/isotherm-ac-dc-converter

BTW, unit documentation says that it has a cutoff when DC power gets to 10(?) volts, but that is pretty low and it didn't seem to work last time.

The usual low voltage cut off is while in operation.

So 10v cutoff (if it works) might be an 11.5v battery.

Inverters are much smarter, adjustable and safer for a batt...

bobbyp said:

Got to the boat a couple days ago after about 4 months away. Boat was at a very nice marina connected to shore power.
Upon opening the refrigerator I noticed that it was not cool at all.

Just as an experiment I tried running it off the 12 volt side and it cools perfectly.

Fridge is a 17 year old isotherm under counter unit.

Seems to me that it would make more sense for the fridge to work on 120v and NOT on 12v.

Any ideas on a simple fix, or is a replacement in my future? Since it has had a nice long life, I'm fine replacing if necessary. Any brands to stay away from?

Thanks as always.

Click to expand...

It made it 17 years. Cost of electronics maybe compressor plus cost of tech ( last week I couldn't spell refridgeerstion, now I are one) to install. Buy new with all new pieces and parts with all the latest and greatest technology. I once paid a certified tech $100.00 for the priviledge of replacing my system in the middle of nowhere after he over filled the refrigerant. Just say'in.

12 volts

When you say to run refrigerator on 12 volts what happens when you are out on the water do you run on 12 volts and run the generator ?As I read this you never run on 110 volts. Tom

tomsboat said:

When you say to run refrigerator on 12 volts what happens when you are out on the water do you run on 12 volts and run the generator ?As I read this you never run on 110 volts. Tom

Click to expand...

When out in the water we flip off the 110v breaker and turn on the 12v breaker, sorry if I wasn't clear.
At the dock or running off the genset we turn off the 12v breaker and turn on the 110v breaker.

Southx10 said:

It made it 17 years. Cost of electronics maybe compressor plus cost of tech ( last week I couldn't spell refridgeerstion, now I are one) to install. Buy new with all new pieces and parts with all the latest and greatest technology. I once paid a certified tech $100.00 for the priviledge of replacing my system in the middle of nowhere after he over filled the refrigerant. Just say'in.

Click to expand...

I looked at the brand new models and they look like they haven't updated the design at all. If I saw something that made a difference I'd probably just spring for a new one.

We had some food spoil seriously badly with the recent refrigeration failure. I cleaned it up really well but as just a lowly crew member the final decision on repair/replace will be based on my wife's nose when she gets back on board in a month or so.

bobbyp said:

I looked at the brand new models and they look like they haven't updated the design at all. If I saw something that made a difference I'd probably just spring for a new one.

We had some food spoil seriously badly with the recent refrigeration failure. I cleaned it up really well but as just a lowly crew member the final decision on repair/replace will be based on my wife's nose when she gets back on board in a month or so.

Click to expand...

You may want to make a final run with a nice fragrant cleaner early the morning of her arrival.

ben2go said:

You may want to make a final run with a nice fragrant cleaner early the morning of her arrival.

Click to expand...

Or not. Sometimes letting things smell worse helps push approval of replacements.

wkearney99 said:

Or not. Sometimes letting things smell worse helps push approval of replacements.

Click to expand...

Of course.