2005 Hunter 36 Fridge and Freezer Power Consumption

[tfox2069]

We had to get a new novacool fridge after a defrosting with a screwdriver went badly.
Frustrating, but the new model is awesome. I can make ice while underway in the ice cube tray!

A pro tip for defrosting (besides not using metal instruments ) is to prop open the freezer compartment and put a fan to blow directly into the freezer compartment. I use a USB rechargeable clip-on fan that we use elsewhere on the boat. That really supercharges the defrosting process - especially in the summer. You can also do other things on your to-do list while that rapidly defrosts! Just put your towels down!

 

[Tally Ho]

I also add a tray of hot water in the fridge, under the freezer plate. I close the lid and let the hot water “steam up” through the icy plate.

No pointy objects allowed!

Greg

 

[quadrille38]

I also add a tray of hot water in the fridge, under the freezer plate. I close the lid and let the hot water “steam up” through the icy plate.

No pointy objects allowed!

Greg

I’ve turned defrosting into a less than 10 minute job. Turn the fridge off. Pull out the food, stuff a towel in the bottom, grab my wife’s blow dryer, 5 minutes later all the ice is removed and the fridge is back in service.
Been doing it this way since 2009.

 

[shemandr]

To go another direction we might do as well or better with a Yeti cooler. I guess it depends on how we use the boats. But if cruising with a stop every 2 days or so, or for overnights the Yeti will keep ice ( I know this from local fisherman who shell out $400+ without blinking because they think it's a value) and frozen close to frozen.
If you consider the extra batteries needed, the charging system to match and the modifications to that old "Ice Box," the expensive cooler doesn't look so bad. I'd have to compare with ripping out the whole mess and putting a quality cooler in with a build out around it. Easy to remove and clean.
I have no relationship with Yeti. And, I think my father would climb out of his grave to give me a dressing down, if he knew I paid $400 + for a cooler.
I've noticed that several racer/cruisers come with a cooler as standard equipment.

 

[PNWE36]

Hi Dan,
I am a little late in the chat but thought I would pass on some information anyways. I have the F1900 freezer in my 2011 H36.
This is an air cooled unit and ventilation is very important along with keeping the components around the compressor clean. Novakool can tell you how many square inches of ventilation is needed.
These units have an option to have a resistor in the thermostat wiring. Based on your current measured you likely have the resistor in place. Mine with the resistor draws 4.8 amps. Without the resistor it is 3 amps. The resistor is for hot climates. I took mine out and even with ambient temperatures at 75 to 80F the freezer worked fine. Disadvantage of removing the resistor is in really hot weather the freezer run continuously and will not be able to keep the temperature setting.
I did a test at 72 F ambient and a setting of 4, temperature in the freezer was 18 to 20 F. The freezer would run for 3.83 min on and 9.5 off. So on about 40% of the time. This test was without the resistor. My unit has the factory insulation on it.
My fridge is an R3800 under the same conditions set at 38 F it draws 2.5 amps and is on about 35% of the time.
As far as recharging these units. Novakool has probably told you if it can be done. If it can be done I think it is worth it to get an experienced refrigeration person to do it. As someone mentioned these units use a small amount of refrigerant. Finding the sweet spot takes skill and a proper gage set up. Also these units can get air in them and if this happens need to be evacuated for several hours before refrigerant can be added. An experienced technician will know if this is required.
Once installed properly with adequate ventilation these units work very well.
Cheers,
Dirk

 

[drm1]

Hi Dan,
I am a little late in the chat but thought I would pass on some information anyways. I have the F1900 freezer in my 2011 H36.
This is an air cooled unit and ventilation is very important along with keeping the components around the compressor clean. Novakool can tell you how many square inches of ventilation is needed.
These units have an option to have a resistor in the thermostat wiring. Based on your current measured you likely have the resistor in place. Mine with the resistor draws 4.8 amps. Without the resistor it is 3 amps. The resistor is for hot climates. I took mine out and even with ambient temperatures at 75 to 80F the freezer worked fine. Disadvantage of removing the resistor is in really hot weather the freezer run continuously and will not be able to keep the temperature setting.
I did a test at 72 F ambient and a setting of 4, temperature in the freezer was 18 to 20 F. The freezer would run for 3.83 min on and 9.5 off. So on about 40% of the time. This test was without the resistor. My unit has the factory insulation on it.
My fridge is an R3800 under the same conditions set at 38 F it draws 2.5 amps and is on about 35% of the time.
As far as recharging these units. Novakool has probably told you if it can be done. If it can be done I think it is worth it to get an experienced refrigeration person to do it. As someone mentioned these units use a small amount of refrigerant. Finding the sweet spot takes skill and a proper gage set up. Also these units can get air in them and if this happens need to be evacuated for several hours before refrigerant can be added. An experienced technician will know if this is required.
Once installed properly with adequate ventilation these units work very well.
Cheers,
Dirk

Thanks Dirk (and everyone else who has helped with answers).

Spring is here so went up to. the boat to start to prep for launch later this month. Took pictures of the model #'s and I was wrong about the model # of my fridge. It is actually the same one you have ... an R3800.

I called the folks at Novakool. Mark was pretty helpful and confirmed what you said in your message. Pull the resistor andthe current draw will go down to 2.4A. Drawback is the recovery time after opening the door will be longer, so potentially compressor may be on longer for a bit but overall mAh should be significantly reduced over a 24 hour period.

The only thing that I'm a bit worried about iswhen it's really hot as you mentioned. this is mostly an issue when we're at the dock and leave the boat for the week. Since we'd be on shore power I'm not worried about the battery consumption, but am worried that everything in the freezer may thaw.

 

[PNWE36]

One thing I thought of doing is install the resistor with a jumper wire around it with a switch in the middle. That way in hot weather, flip the switch and have the fridge run at higher current.

 

[Hayden Watson]

One thing I thought of doing is install the resistor with a jumper wire around it with a switch in the middle. That way in hot weather, flip the switch and have the fridge run at higher current.

I proposed doing this several years ago when I installed my Inkbird thermostat and actually have the 1.5kΩ resistors on my desk. In my case, I found that I never need it to run faster than 2000-rpms given that my PWN water is cold, the air temperature is cool, and my fridge is small. If I understand your proposed circuit, I think your switch is in the wrong place. You need to have two paths for the T-stat wire. One goes through a 1.5kΩ resistor and the other goes through the switch. If the switch is open, all current flows through the resistor and you have a total resistance of 1.5kΩ. With the switch closed, the current is divided between the 1.5kΩ and 0Ω path which results in a total resistance of vert bear 0Ω.

 

[AndyL]

Our 2004 Hunter 36 had a Nova Cool R3800 which died a couple of years ago. We replaced it with an identical unit. It sure does use a lot of power. I've seen claims that it draws 2.2 amps but our battery monitor was showing double that. And when it's 90 degrees, it is cycled on a lot of the time. This season I want to do some more checking of power use at different temps. Also we might try turning the thermostat to a slightly warmer setting.

 

[Hayden Watson]

Our 2004 Hunter 36 had a Nova Cool R3800 which died a couple of years ago. We replaced it with an identical unit. It sure does use a lot of power. I've seen claims that it draws 2.2 amps but our battery monitor was showing double that. And when it's 90 degrees, it is cycled on a lot of the time. This season I want to do some more checking of power use at different temps. Also we might try turning the thermostat to a slightly warmer setting.

The short cycling of the mechanical thermostat was what drove me to installing the digital thermostat. With mechanical, you are just checking the temperature of the aluminum evaporator plate. On mine, it would be on 5 minutes and off 10-minutes whenever the fridge was turned on. It kept me awake at night listening to it go on and off. With the digital thermostat, you are checking the air temperature of a location out inside the box. On mine, I mounted the sensor to the bottom of a shelf rack which gives a good average. Now, it will run for about 20-30 minutes and then will stay off for a couple of hours. I set the thermostat so that it turns on when the air temperature hits 40º and off when it drops to 33º.
The conversion was totally simple, and I left the mechanical T-stat as a backup. You run a wire from the T and C terminals to the relay and supply + & -. On my Adler Barbour system I was able to do it all with a phone plug.