Dometic 4223 to NRX 60?

[Shawn S]

I am working on a big update to my camper. Moving from one 12 volt AGM, to a solar system with lithium batteries. The road block I am at is that I need to calculate my electrical needs. At some point I would like to update my other components, so my plan is to start my conversion to solar by updating my appliances, which in turn will decrease the load on my current battery, and once everything is done on that side I can accurately calculate my electrical needs for my lithium/solar swap.

I am trying to figure out the fridge right now. I am thinking about swapping out my Dometic 4223 to a Dometic NRX 60. Has anyone done a similar swap? The 60 seems to be smaller, 2.05 cu ft vs the 2.5 cu ft of the 4223. But the next size up, the NRX 80, is 4" taller than my 4223 so that won't work well. The NRX 60 seems considerably more efficient than the 4223.

Has anyone done a similar swap? Am I missing anything here, will the NRX 60 be a suitable replacement for a 4223?

 

[Vic Harder]

Shawn, I can't speak to the fridge question, but I wonder if you have a shunt based SOC monitor in place now already, so you can tell what your current usage is? Any of the newer 12v only or 12/120v Indel (compressor style) fridges will use way less power than the 3-way (propane) fridges. You also have not mentioned usage patterns for yourself, and what all you are trying to run off of your batteries.

I have observed that most folks who have fans, fridges, lights, computers, phones, cell boosters etc to run, use about 45-55AH a day. So to run 3 days without charging (a long weekend for example) you need 150-200AH of useable battery. 200AH of LiFePo4 will do that, as would 400AH of AGM. And to balance that, you want at least 400W of solar or alternator equivalent to recharge them (industry rule of thumb = 2x Solar Watts of the AH battery bank).

I hope that helps, and please do ask more questions as they occur to you.

 

[Shawn S]

Vic, I am flying blind. We don't have monitor. On a really cold night it hasn't been uncommon to wake up with the furnace not running because the Atwood fan sucked the battery dry. That was last year when we had an old AGM battery, I did put a new AGM in to get me through this winter while I work through this electrical conversion. So maybe we won't have that issue this year, but that's part of the problem I am trying to solve, we are running off of maybes and really don't know where we sit on power or even power consumption.
Is there a monitor that you recommend that could help me learn more about my current system, so I can gain a better understanding of what my needs will be?

 

[Vic Harder]

yup, get the Victron Smart Shunt. PKYS.com has them. No affiliation, but I have bought two campers worth of electronics from them with no problems.