Nova Kool R4500 Fridge Cooling Issue on DC - Troubleshooting

[kpfn1216]

Hi all,

I'm seeking advice on a cooling issue with my Nova Kool R4500 DC refrigerator. It functions well when plugged into AC power, but doesn't cool when operating on DC. Here's the background, and what I've checked:

- The fuse on the boat's panel is intact.
- The light inside the fridge turns on, so it seems to be getting some power on DC.
- The compressor and thermostat appear to be working since it cools normally on AC.
- I didn’t realize there was an issue until we started a trip without pre-cooling the fridge on AC. Even after running on DC for a full day, the fridge never cooled down.

Given that it operates correctly on AC, the compressor and thermostat likely aren't the problem, which leads me to suspect a potential issue in the DC wiring or components. I've checked the basic settings and connections without dismantling anything, all of which seemed normal.

Could anyone offer insights or further troubleshooting steps for issues in these units? Any experiences with similar issues or common faults to look out for would be greatly appreciated.

Thanks in advance for your help!

- Kevin

 

[LMRanger]

Correct me if I'm wrong, but the NovaKool does not get 120v AC.
The refrigerator is run on 12V DC current, so even when plugged into shore power its running on 12, and the battery charger/solar is keeping the battery charged.
Check your charger/inverter and other DC panels and fuses.

Ralph

 

[jeffhowell1]

Ralph, you are correct, refrigerator on Ranger runs on 12 volt, so yes monitoring charger/inverter is advised

Kevin, what year and model is your boat?
It is quite possible your fridge is done

I have 2012 R-27 replaced the Nova Kool R4500 fridge with Isotherm Cruise 130 last year, works so much better. Our old Nova Kool kept freezing things even at low setting, very annoying, and a pain when out for days.

Email me at howellhere@hotmail.com if you want installation details.

The original fridge must have been installed before cockpit door and frame because I had to cut it apart to get it out.
New Isotherm Cruise 130 fit through door frame, just barely

In my opinion, Cruise 130 is serious upgrade in usability and performance to Nova Kool R4500

 

[kpfn1216]

Ralph and Jeff,

Confirmed, it’s DC only. Just got to pull it out.

For anyone in the future: the manual is a bit confusing as it references an AC wiring option, but it’s just that they have a single manual for multiple models. The 4500 does not have the AC line and neutral inputs as in the manual, just the DC inputs. This is obvious in retrospect, but was confusing at the time…

I think the AC/shore power observation was likely a fluke and coincidentally times with an intermittent connection.

After walking through the troubleshooting guide, I think I’ve narrowed it down to either the thermostat or the speed resistor. The speed resistor is a small 1500 resistor in series with the “T” input that regulates the power it runs at (I think). My speed resistor broke in half when I attempted to remove it, so I think it may have been a weak link. I’ve got everything rewired without it, and it appears to be cooling.

I’ll update once I get a new speed resistor for anyone else that has this issue, or if it ends up being something else (other wiring issues or thermostat seem most likely still).

Also very much still open to any other troubleshooting advice.


Sent from my iPhone using Tapatalk

 

[Gin]

Give NovaKool’s tech support a call. Real people with real knowledge answer the calls. A few years back I called them on a Nova Kool installed in our Sprinter van, and they took plenty of time with me and were a big help.

Isotherm is a great product, but I wouldn’t discourage anyone from upgrading to one. But FWIW, I was talking to a marine tech friend about the unit in my Sprinter van back when I had an issue with it He asked the brand. I said Nova Kool. He responded, “Well, they are all repairable. But with all the brands except Nova Kool, the repair is to pull it out, throw it away, and replace it. Nova Kool actually makes units that can be repaired.” Which is what led me to call their support line and to a successful repair.

That’s his expertise talking, not mine. So again, FWIW.

Gini

 

[DocJoe]

Give NovaKool’s tech support a call. Real people with real knowledge answer the calls. A few years back I called them on a Nova Kool installed in our Sprinter van, and they took plenty of time with me and were a big help.

Isotherm is a great product, but I wouldn’t discourage anyone from upgrading to one. But FWIW, I was talking to a marine tech friend about the unit in my Sprinter van back when I had an issue with it He asked the brand. I said Nova Kool. He responded, “Well, they are all repairable. But with all the brands except Nova Kool, the repair is to pull it out, throw it away, and replace it. Nova Kool actually makes units that can be repaired.” Which is what led me to call their support line and to a successful repair.

That’s his expertise talking, not mine. So again, FWIW.

Gini

 

[DocJoe]

THIS DISCUSSION SUGGESTED TO ME A QUESTION.

I HAVE A DC ONLY REFRIGERATOR IN MY 2019 R23, SO COULD I INSTALL AND CONNECT AN AC-TO-DC CONVERTER, SO I CAN RUN THE REFRIGERATOR WHILE ON SHORE POWER THUS BYPASSING THE INVERTER AND THE BATTERIES, AND USING AC POWER ONLY?

THANKS FOR ALL HELP AND SUGGESTIONS,

JOE

 

[scross]

THIS DISCUSSION SUGGESTED TO ME A QUESTION.

I HAVE A DC ONLY REFRIGERATOR IN MY 2019 R23, SO COULD I INSTALL AND CONNECT AN AC-TO-DC CONVERTER, SO I CAN RUN THE REFRIGERATOR WHILE ON SHORE POWER THUS BYPASSING THE INVERTER AND THE BATTERIES, AND USING AC POWER ONLY?

THANKS FOR ALL HELP AND SUGGESTIONS,

JOE

Here’s my understanding of the R4500. The model used is12 volt DC only. I’d suggest you have a long conversation with NovaKool customer service before trying to convert it to both DC and AC operation. A new AC/DC dual power R4500 unit is about $1,600.
But really, why would you want to do a huge project like that? The R4500 runs off the house battery bank. The house bank is charged by one or more of these system - a solar controller, the engine alternator, A/C shore power and/or the optional generator. Running the refrigerator has nothing to do with the inverter in normal 12 volt operation. Using the inverter to power a AC powered refrigerator would be hugely inefficient. Doing so repeatedly could kill your house battery bank.
That’s my understanding. If I’ve got that wrong I’ll be glad to be educated.

 

[DocJoe]

Here’s my understanding of the R4500. The model used is12 volt DC only. I’d suggest you have a long conversation with NovaKool customer service before trying to convert it to both DC and AC operation. A new AC/DC dual power R4500 unit is about $1,600.
But really, why would you want to do a huge project like that? The R4500 runs off the house battery bank. The house bank is charged by one or more of these system - a solar controller, the engine alternator, A/C shore power and/or the optional generator. Running the refrigerator has nothing to do with the inverter in normal 12 volt operation. Using the inverter to power a AC powered refrigerator would be hugely inefficient. Doing so repeatedly could kill your house battery bank.
That’s my understanding. If I’ve got that wrong I’ll be glad to be educated.

THANK YOU. I WOULD NOT ALTER THE INTERNAL VOLTAGE REQUIREMENTS OF THE FRIG, I WOULD SIMPLY CONNECT THE DC FRIG CIRCUIT TO AN AC-DC CONVERTER.

A CONVERTER IS NOT THE SAME AS AN INVERTER, IN FACT, THEY PERFORM OPPOSITE FUNCTIONS. THE AC-DC CONVERTER IS TYPICALLY A SMALL ELECTRICAL COMPONENT (IE, A TRANSFORMER) THAT PLUGS INTO A STANDARD WALL PLUG FOR 110V 15AMP POWER, THEN, THE THE VOLTAGE IS CONVERTED INTO 12V DC POWER OF SAME AMPERAGE.

SO, NO WIRING CHANGES TO THE FRIG, IT CONTINUES TO RECEIVE 12V DC POWER AS NORMAL.

THE DIFFERENCE IS I AM NOT THEN USING MY INVERTER OR MY BATTERIES TO RUN THE FRIG ON DC, RATHER, I AM USING THE SHORE POWER 110V AC CONVERTED TO 12V DC TO POWER THE FRIG. THAT AVOIDS USING MY BATTERIES TO KEEP THE FRIG COLD WHILE ON SHORE POWER.

MY QUESTION WAS IS THIS AN OK THING TO DO, HAVE OTHERS DONE THIS, OR AM I MISSING SOMETHING.

THANKS AGAIN. /JOE

 

[Rode Trip]

THANK YOU. I WOULD NOT ALTER THE INTERNAL VOLTAGE REQUIREMENTS OF THE FRIG, I WOULD SIMPLY CONNECT THE DC FRIG CIRCUIT TO AN AC-DC CONVERTER.

A CONVERTER IS NOT THE SAME AS AN INVERTER, IN FACT, THEY PERFORM OPPOSITE FUNCTIONS. THE AC-DC CONVERTER IS TYPICALLY A SMALL ELECTRICAL COMPONENT (IE, A TRANSFORMER) THAT PLUGS INTO A STANDARD WALL PLUG FOR 110V 15AMP POWER, THEN, THE THE VOLTAGE IS CONVERTED INTO 12V DC POWER OF SAME AMPERAGE.

SO, NO WIRING CHANGES TO THE FRIG, IT CONTINUES TO RECEIVE 12V DC POWER AS NORMAL.

THE DIFFERENCE IS I AM NOT THEN USING MY INVERTER OR MY BATTERIES TO RUN THE FRIG ON DC, RATHER, I AM USING THE SHORE POWER 110V AC CONVERTED TO 12V DC TO POWER THE FRIG. THAT AVOIDS USING MY BATTERIES TO KEEP THE FRIG COLD WHILE ON SHORE POWER.

MY QUESTION WAS IS THIS AN OK THING TO DO, HAVE OTHERS DONE THIS, OR AM I MISSING SOMETHING.

THANKS AGAIN. /JOE

Where's the benefit? The AC to DC converter is just a small battery charger. Why not use the battery charger you already have permanently installed? When hooked to shore power the battery charger is powering the fridge, not the batteries. Your inverter has nothing to do with the fridge. What happens if you lose shore power for a few hours? In your scenario the fridge shuts off, but if you use the system that was designed, built, and installed already the batteries could fill in. Also every time you use the boat you won't have to switch between your new converter and the existing 12 volt system. Why would you not want your battery charger keeping your batteries topped up and on a float charge while you're on shore power while at the same time running your fridge?
I just don't see a single positive advantage to what you're proposing.

 

[Jcat2010]

Slightly different issue re refrigerator issues. Same nova cool, but at least once per season we will find it "off". No lights, ice melted. Pull the fuse, put it back in, comes back on. Seems to be on hot days. I suspect the fuse holder might have some issue, but haven't had the time to remove and inspect.

 

[DocJoe]

Andy,

So it's OK to leave the frig 'on' while connected to shore power, because the frig is drawing DC current from the battery charger, and not the batteries? I thought the battery charger only supplied current to the batteries, and varies the current according the needs of the batteries, and can even shut off when batteries are topped off. Am I wrong about that?
I am still learning about my boat, and truly appreciate your insight and suggestions.
Thanks again, /Joe

 

[CaspersCruiser]

So it's OK to leave the frig 'on' while connected to shore power, because the frig is drawing DC current from the battery charger, and not the batteries?

The refrigerator is always powered by the house batteries. Period. When connected to shore power and the battery charger is ON, the battery charger will keep the batteries charged as they supply current to the refrigerator and whatever DC appliances are in use— interior and exterior lights, TV, stereo, and so on.

 

[scross]

Andy,

So it's OK to leave the frig 'on' while connected to shore power, because the frig is drawing DC current from the battery charger, and not the batteries? I thought the battery charger only supplied current to the batteries, and varies the current according the needs of the batteries, and can even shut off when batteries are topped off. Am I wrong about that?
I am still learning about my boat, and truly appreciate your insight and suggestions.
Thanks again, /Joe

CaspersCruisers is correct (as usual) that nothing is “powered” by the battery charger itself except for putting a charge into the house battery bank. (Not counting the ACRs which kick in when the house bank is fully charged then “move” the battery charging function to the other battery banks.)
The house batteries, not the charger, supply 12 volt DC power to all the DC systems in the boat - other than the engine start and thruster functions which have dedicated battery banks. All lights, TV, stereo, helm instruments, pumps, etc, etc. operate on 12 volts DC.
On our 2017 NW Edition C-28 the only appliances in the boat that are 110 volt AC powered are the microwave, Keurig coffee maker and the 110 AC outlets.
We upgraded to 335 watts solar, leave the house bank rotary switch on with only the refrigerator and “always on” (e.g. CO detector, bilge pumps and stereo memory) systems running for weeks at a time in rainy & cloudy WA on the trailer and not connected to shore power. The house bank has never been under 70% SOC while the boat is on the trailer. Solar charging alone keeps everything in the fridge cold without any problems by keeping the house battery bank charged up!

 

[scross]

Post sent tonight from Goat Island Anchorage on Crease Island, the Broughtons. Can’t believe I’m getting cell coverage up here!

 

[Rode Trip]

Andy,

So it's OK to leave the frig 'on' while connected to shore power, because the frig is drawing DC current from the battery charger, and not the batteries? I thought the battery charger only supplied current to the batteries, and varies the current according the needs of the batteries, and can even shut off when batteries are topped off. Am I wrong about that?
I am still learning about my boat, and truly appreciate your insight and suggestions.
Thanks again, /Joe

Hi Joe, as the others stated in a different way, you can think of the batteries as a giant bucket that has taps on it for water to flow out to other loads. (but electricity is flowing, not water in reality) Whenever something needs electricity, like the fridge, the water flows out of the bucket (battery) to the load. The battery charger is a big spigot that dumps water into the bucket, always trying to keep the bucket full. If you start draining more out of the bucket, the spigot will dump more in to make up for the loss from the bucket. As long as the charger is running it will keep the bucket full (to a point, it's only a 20 amp charger or similar). If you turn the spigot (battery charger) off then the bucket can be depleted. So as long as you keep the charger/spigot on you can safely run lights, fridge, electronics, etc and the batteries/bucket will not deplete.

 

[CaspersCruiser]

My post, Al’s post, and Andy’s excellent bucket/spigot analogy all describe how the DC power system works when on shore power and the battery charger is in operation. When away from shore power, there are three ways to keep the battery bucket full— the engine alternator and, if so equipped, the solar panel and generator.

When the engine is running, alternator output is regulated to provide a constant 14.2 volts DC to the batteries to keep them charged as they power the DC appliances on the boat.

When the engine is not running and the boat is equipped with a solar panel, the solar panel will charge the batteries through solar panel controller. The solar panel controller on my boat is set to send 90% of the solar panel output to the house batteries and 10% to the engine battery. Depending on how many watts of solar are available and what DC appliances on the boat are in operation, the amount of DC current flowing into the house batteries from the solar panel can be exceeded by the DC appliance load and start draining the house batteries.

If your boat is equipped with a generator, it provides AC power and will run the AC appliances on your boat exactly the same as shore power subject to the limits of the generator’s output. The Mase 2.7 generator on my 2012 R27 only produces 2200 watts which is a little more than 18 amps so I have to be careful not to exceed that. Shore power on the 8’6” beam boats is 30 amps.

 

[DocJoe]

Thank you for all the useful and helpful comments. I feel informed now! 🙂.
I'll scrap my idea of installing a converter.
While on shore power turn frig 'on' and make sure battery charger is 'on' too.
Got it! Thanks again for this valuable info for me, the novice. /Joe

 

[scross]

Thank you for all the useful and helpful comments. I feel informed now! 🙂.
I'll scrap my idea of installing a converter.
While on shore power turn frig 'on' and make sure battery charger is 'on' too.
Got it! Thanks again for this valuable info for me, the novice. /Joe

Joe, something you might consider that’s pretty easy to do is upgrade your solar panel and solar controller so the batteries will stay safely charged even if shore power goes out for whatever reason. There are a lot of threads on this site on how to do it. Prices for panels and controllers have really dropped in the past 2-3 years. You can get all the parts needed for 400 watt system for under $500 these days (VE 100/30 Smart Solar controller for $130 and 400 watt panel for under $300) if you’re a savvy shopper. I installed mine in about 5 hours total.