Nova Kool 12V Operation

[Protagonist]

Originally Posted by Cirrus Flyer

One other thing from our experience. If batteries get below 10v the NK will be disconnected to conserve power. Happened one time while on DC. We do get warnings by solar control unit flashing low when voltage critical and have been able to avoid the shutdown without problems.

But if batteries get below 10v, the inverter won't work either. 10v is below 0% charge on a 12v battery.

[Ron_CA]

Something isn't right as suggested above. If you keep your inverter turned on all the time, you will be hard pressed to keep your batteries charged when not hooked up to shore power. Check your fuses.

You may want to try a quick and easy test by unplugging your refrigerator as I posted above to see if it works on 12v, you can always plug it back in. Try it with the inverter turned off.

[Cirrus Flyer]

We have not seemed to have problems with charging from the alternator while underway with inverter on or if recharging when stationary and not on shore power if we do so every 8-12 hours.
I am underway ( wife driving) so don't know about unplugging when we get home. Really don't understand where the plug is or what the foam door is to remove.
Thanks

[Ron_CA]

Underneath the sink is a tilt out (I call it) sponge drawer. Tilt it out, loosen 2 screws that hold the plastic tray in place, remove the tray, reach in and unplug (normal plug into regular outlet) the refrigerator. Your refrigerator should still work on 12v only.

Wait until you get home and off the road.

[Cirrus Flyer]

Ours is opposite the sink. I have one candidate that maybe the one, but I thought was for TV located above. Project for later.

[Ron_CA]

When you posted above you said 2015IS. I thought you had an Interstate but you have a Grand Tour. Not sure where the plug is on that.

Just for clarification:

Do the 2015 Grand Tour's say Interstate Grand Tour? Or are they either an Interstate or a Grand Tour?

OK, just went on Airstream website and it is in fact:

2015 Interstate Grand Tour EXT

FYI...you may be better off posting in the future as a Grand Tour so you don't confuse dummies like me

[73shark]

Since it's a Grand Tour, doesn't it have a separate freezer section type refrigerator? If so, maybe it doesn't run on 12 volts at all. I doubt it but anything it's possible.

[UKDUDE]

Originally Posted by 73shark

Since it's a Grand Tour, doesn't it have a separate freezer section type refrigerator? If so, maybe it doesn't run on 12 volts at all. I doubt it but anything it's possible.

Interesting observation: I had thought the fridge in the Grand Tour was a 2-door fridge-freezer. But the 2015 Parts Book has different part numbers for the fridge and freezer, which sort of infers they are 2 individual units.

[tlundell]

Originally Posted by UKDUDE

Interesting observation: I had thought the fridge in the Grand Tour was a 2-door fridge-freezer. But the 2015 Parts Book has different part numbers for the fridge and freezer, which sort of infers they are 2 individual units.

Yes, they are separate units, each sitting on a separate shelf one above the other.

[TOdehnal]

Originally Posted by TOdehnal

So, it sounds like if we fire the gen in the evening, do a little microwave, or convection cooking, and watch a little TV, while the batteries are being topped off, that I should have no problem making it through the night, and recharging after 8:00 the next morning.
Thanks for the replies. It was a great help.......Tom

After posting the question about the frig run time on battery power, I also requested info from the supplier. The following was the reply, and I thought it worth posting here, as well.

______________________________________
How many Hours will my Nova Kool R3100 Refrigerator operate while on my batteries?

There are several variables that will influence this. From how many lights we run to how often we operate other 12 volt items. However, if we take these other items out of the equation and simply calculate refrigerator operations.

Here is what we have.

2 Discover Batteries 84 amp hours.

NovaKool using 1.25 amps per hour.

Amp hours are double to 168 this is divided by 1.25 amps to equal 134.4 this will be hours. So we divide this by 24 hours and come up with 5.6 days of operation.

So we will get approximately 5.6 days of use from the refrigerator

.

[73shark]

Is the 1.25 amps per hour the average or is that assuming the refrigerator is running continuously?

[TOdehnal]

My guess is that it is an average............Tom

[lewster]

Originally Posted by TOdehnal

After posting the question about the frig run time on battery power, I also requested info from the supplier. The following was the reply, and I thought it worth posting here, as well.

______________________________________
How many Hours will my Nova Kool R3100 Refrigerator operate while on my batteries?

There are several variables that will influence this. From how many lights we run to how often we operate other 12 volt items. However, if we take these other items out of the equation and simply calculate refrigerator operations.

Here is what we have.

2 Discover Batteries 84 amp hours.

NovaKool using 1.25 amps per hour.

Amp hours are double to 168 this is divided by 1.25 amps to equal 134.4 this will be hours. So we divide this by 24 hours and come up with 5.6 days of operation.

So we will get approximately 5.6 days of use from the refrigerator

.

The only problem with their calculations are the battery capacity. They are effectively draining them to zero, which in the real world is an impossibility. The other factor that they did not consider was the internally programmed cut-off voltage for most electronic control boards....that being somewhere between 10.5 and 11.0VDC.

In reality, given the battery size in the example, you don't double the capacity as you use a 50% depth of discharge as an effective 'floor' for your batteries' health. This provides you with 84 'usable' amp/hours of capacity and will give you, at the stated 1.25 amps per hour draw rate (which is a bit low for a Danfoss compressor fridge) will give you 62.2 hours of run time to your 50% battery level, or 2.6 days with no additional DC loads on the batteries and no additional charging input from things like solar.

I generally use the stated amp draw listed in the manufacturer's specification sheet and divide by 2, which then assumes a 50% duty cycle for the fridge compressor, as they really don't run continuously. This is the factor that I divide into the battery bank capacity to estimate true run time.

[TOdehnal]

Thanks Lewster. I'm still good with that. As long as I can rely on a solid 15 hrs of service without a charge, that will work for us, and it looks like we could have a solid 2 days, which is fantastic. By the way, I am sure that calculation is for a "per unit", and the AI has 2; one frig, and one freezer. With that, I still think that with both units running, I should be able to rely on a full 24 hours, without an issue. This has been interesting!

Tom

[73shark]

In with your 100 watt solar panel, 24 hours shouldn't be a problem, even on cloudy days.

[tlundell]

Update: I started this thread with the unresolved problem of the Nova Kool freezer in my 2015 Grand Tour not operating on 12v. Diagnosis and repair: my local RV repair shop pulled the freezer and found that the 12v power wire was not connected. Small repair bill, but I am hoping that my dealer (who did not perform the repair...too far away) can get reimbursement from Airstream

[lewster]

Originally Posted by tlundell

Update: I started this thread with the unresolved problem of the Nova Kool freezer in my 2015 Grand Tour not operating on 12v. Diagnosis and repair: my local RV repair shop pulled the freezer and found that the 12v power wire was not connected. Small repair bill, but I am hoping that my dealer (who did not perform the repair...too far away) can get reimbursement from Airstream

Don't see why not....their assembly error..........DUH!

[gghayes]

Ok, here is my story's. We purchased our interstate grand tour in Jan 2015. The refrigerator worked fine until the weather got hot and then it did not cool below 48 to 52 degrees. The dealer did the "fix" which was to make larger vents and to install a fan. This did not work, so finally in Oct. we got a new refrigerator. We went on an extended 6 week trip in May and the refrigerator still would not cool properly. I resorted to putting frozen bottles of water and a chunk of ice in the refrigerator. This kept it between 42 and 48. We ended up in Texas where the weather was 90 and my refrigerator went up top 60 degrees. After talking to nova Kool and airstream, it was decided that the airstream reps would look at the unit at the international rally. At that point, they put in a new resistor. This did not change anything, so now I am waiting for Nova Kool as they said they value their relationship with airstream and are going to build me a new refrigerator to fit the interstate. Will know in 2 weeks..
Gloria

[Lily&Me]

Yikes, Gloria!

You guys have had a slew of issues with that rig.


Maggie

[gghayes]

Don't you know it Maggie., and I haven't even told anyone my tire stories in regard to to TPM
Gloria