Nova Kool 12 Volt DC Refrigerator

[Barry Cohen]

Has anyone noticed reduced performance (a.k.a. rise in temperature) in their refrigerator when the battery charge starts to deplete?

 

[sleepyboat]

Barry,
The short answer is yes. I left my refrigerator on thinking the solar panel would keep up with the use. I came back to the boat in three days and found the frige shut-down and batteries in the low elevens. With the batteries in the mid 12’s I found my beers in the freezer for the quick chill option were starting to freeze.
John

 

[Barry Cohen]

Thanks John. That was partly my experience this past weekend. As the batteries declined, the temp rose to about 54. I turned on the generator to charge the batteries and the temperature slowly dropped.

 

[swillmerchant]

Do you guys have any estimate of how long the refrigerator can run on a fully charged battery? I haven't tried it thinking it would draw too much juice between visits to the boat and leave the batteries too depleted upon my return.

 

[Barry Cohen]

Hey Doug:

I recall losing the house battery after 3 days when I forget to put my shore power switch on last year.

 

[sleepyboat]

Doug,
Mike Rizzo did some number crunching in 2011 for refrigerator draw on the house batteries. We both have a solar panel and no generator. The fridge is a power hog and I think I decided not to leave it on more than two days at a mid-dial setting without an engine run or fridge shut down. Clearly three days was the limit for me.
John

 

[Crewdog]

As a test, I connected our NorCold 30 to a fully charged 5 year old Optima Blue Top car battery in the basement, ambient temp about 70.

At 5 degrees F, the cooler functioned for about 22 hours before the voltage error light came on. Battery was reading about 11.3 volts using a dc voltmeter directly across the terminals with no load on.

At 35 degrees F, the cooler functioned for about 28 hours before voltage dropped enough that cooler wasn't operating.

There is a switch on the model we have that tells the cooler what voltage to cut off at, that was left at factory default of 11.3 vdc cutoff.

Both times the battery re-charged overnight using a Battery Tender Plus Jr.

 

[tlkenyon]

Do you know the amp-hour rating of the Optima battery?

 

[Crewdog]

Hi:
Optima Blue Top
Group D34
55 amp hrs
750 CCA

and it is 5 yrs old, used only occasionally

Bill

 

[knotflying]

Bill's numbers are pretty close. If my memory serves me correctly the Unit will draw about 2.2 amps at 75 degrees ambient. So just do the numbers based on your battery amp hours. The time should extend somewhat longer if you add back in the amp hours that you will get from your solar panel.