Replacing Norcold Fridge: get 2 way or 3 way?
I am replacing my 1998 Norcold N9162 with a Norcold N641 or N641.3. (6.3 cubic feet) Do you guys recommend I get the 3 way or will the 2 way be fine? I have 2 6 volt deep cell batteries in series ...
Forum Discussion
“ Does anyone know the difference between the N641 or the N641.3? ”
The “ .3 “ means 3-way.
Running the fridge in DC mode will require a means of continuously supplying your RV with >12 volts DC at a minimum of 20 amps to avoid drawing your house batteries down to unacceptable levels while driving. The typical RV +/- 12 volt DC circuit, especially on trailers, is completely incapable of doing that. You’re lucky if they can even do 10 amps on a continuous basis. The circuit length is too long, the wire size is too small, the standard 7-pin RV plug is a poor design that introduces voltage and current drop, and nowadays the tow vehicle’s alternator is under the complete control of the ECM that’s doing everything it can to reduce its load on the engine.
It can be done, but it requires $$$ and some work on your part. If you’re not willing to invest in a 25-30 amp DC-DC battery charger, and the higher gauge wires it will require, and replacing the 7-way flat blade RV plug with one that can actually support the higher amperage needed, you’re better off sticking with LP mode on the fridge while you’re driving.
Also keep in mind that even a 2-way reefer can be run in AC mode from a small inexpensive MSW inverter while driving. But, because the AC heater in most RV fridges is a higher BTU than the DC heater, even more DC amperage will be needed to keep up with the load on the RV battery.
I actually am running my reefer in DC mode while driving, and it works very well. But, I have a 25 amp DC-DC charger in the camper, an upgraded DC circuit running to the camper that’s all 2 AWG wires, a better plug than the standard RV 7-pin, and the total circuit length is much shorter than any towable RV would be.
You’d be surprised just how long the circuit length to the TC actually is though, when you start adding up all the wire lengths between the truck and the camper. You’d also be surprised how well the fridge DC mode works when the voltage to the fridge is being maintained at >13-14 volts, thanks to the DC-DC charger.
:):)
The “ .3 “ means 3-way.
Running the fridge in DC mode will require a means of continuously supplying your RV with >12 volts DC at a minimum of 20 amps to avoid drawing your house batteries down to unacceptable levels while driving. The typical RV +/- 12 volt DC circuit, especially on trailers, is completely incapable of doing that. You’re lucky if they can even do 10 amps on a continuous basis. The circuit length is too long, the wire size is too small, the standard 7-pin RV plug is a poor design that introduces voltage and current drop, and nowadays the tow vehicle’s alternator is under the complete control of the ECM that’s doing everything it can to reduce its load on the engine.
It can be done, but it requires $$$ and some work on your part. If you’re not willing to invest in a 25-30 amp DC-DC battery charger, and the higher gauge wires it will require, and replacing the 7-way flat blade RV plug with one that can actually support the higher amperage needed, you’re better off sticking with LP mode on the fridge while you’re driving.
Also keep in mind that even a 2-way reefer can be run in AC mode from a small inexpensive MSW inverter while driving. But, because the AC heater in most RV fridges is a higher BTU than the DC heater, even more DC amperage will be needed to keep up with the load on the RV battery.
I actually am running my reefer in DC mode while driving, and it works very well. But, I have a 25 amp DC-DC charger in the camper, an upgraded DC circuit running to the camper that’s all 2 AWG wires, a better plug than the standard RV 7-pin, and the total circuit length is much shorter than any towable RV would be.
You’d be surprised just how long the circuit length to the TC actually is though, when you start adding up all the wire lengths between the truck and the camper. You’d also be surprised how well the fridge DC mode works when the voltage to the fridge is being maintained at >13-14 volts, thanks to the DC-DC charger.
:):)
