Real World Results from Dometic CFX-50w

[SBSYNCRO]

As I've posted in another thread, I'm running the Dometic fridge in my 4-door Jeep powered by a Suaoki G500 lithium power supply (500WH unit for $389 on Amazon). I have a 100w HQST panel mounted to a Rhino Vortex rack using some L-brackets that I fabricated.

Components of my setup: (not affiliate links)

Dometic CFX-50w Fridge
DFG Offroad slide
Suaoki G500
HQST 100w panel
Angle brackets for panel mounts
Thumb knobs for panel mounts

When I was researching my system, I found it very difficult to get a good assessment of a number of things that I am going to try to update here in this thread as I learn/discover them for myself. Such things as:

1. How much power will it really draw in a real world scenario?
2. Is a 500WH battery system "enough"?
3. What is the impact of adding a solar panel? What size panel should I get?
4. Is a 50L Fridge the right size?
5. Whats the best way to mount it in a lifted Jeep?
6. What is a good way to wire everything up?


Here are my initial findings, which I will update as I learn more and/or modify my system. I hope this thread becomes a resource for people considering the 50 liter Dometic fridge (or other similar fridges).

Power Draw

Indoor (ideal scenario) shows that the fridge cycles on for 3 minutes every 30 minutes when set to 39 degrees F and the ambient temp is about 70 degrees F. This is without the insulated cover (which I plan to add) and without opening the fridge. When the fridge cycles, the indicated power draw averages about 50 watts during those 3 minutes (off DC and about 58 watts off AC). If my math is right, then this is 2.5 watt hours. Assuming that the cycle rate is the same for 24 hours (it will usually be cooler at night and thus cycle less often) then this is about 120 watt hours every 24 hours, or a little over 20% of the capacity of the Suaoki G500 battery pack I'm using.

Empirically, I've seen similar results in the field, but the biggest difference being that the cycling can occur more frequently with warmer ambient temps and opening the fridge to prepare dinner and grab cold drinks. I've found that if the battery is fully charged on solar until the sun sets to the point where it is no longer charging the battery (around 4:30 pm), and then the fridge is used to make dinner and grab drinks, with an overnight temperature starting around 70 degrees and then dropping to the low 50's, I will see the battery indicator has dropped 2 bars (each representing 20% of the 500 watt hour capacity) but will very quickly recharge to 1 bar, telling me that its just barely past the 20% threshold. I can deduce from this that the fridge is consuming slightly more than 100 watt hours each night. During my weekend testing in the desert, I was able to start charging again at around 8 AM, making for about 15-1/2 hours of operating time without any charging.

Bottom line, after the morning clouds cleared, I was able to top up the battery 100% each morning by the time I was done putting away breakfast and getting ready to explore for the day if we were on a "gentlemen's schedule" (e.g. lazy start). Using the 100w panel in strong sun provides about 50 to 60 watts early in the morning (7 am to 10 am), gradually increasing to 75 watts by 10 am and 90+ watts by noon. On mornings when we want to head out exploring early in the day, I mounted the panel back on the roof of the Jeep and the battery was always 100% charged by the time we got back to camp in the evening while also powering the fridge all day on the trail.

I found that because of the high efficiency and greater throughput of the solar charge controller built into the Suaoki unit, I was MUCH better off using solar versus using the 12v receptacle that I installed in the back of the Jeep to recharge the battery pack. One day using the 12v receptacle, I arrived back at camp in the early afternoon to see that my state of charge had not changed at all, even after about 4 hours on the trail (meaning that the fridge had essentially consumed all the power provided yielding no net gain or loss to the battery). I quickly deployed my solar panel angled to the sun and after a few hours was able to fully charge the battery. Lesson Learned: don't bother with the 12v receptacle - just use the solar panel all the time.

More to come....

 

[67cj5]

As I've posted in another thread, I'm running the Dometic fridge in my 4-door Jeep powered by a Suaoki G500 lithium power supply (500WH unit for $389 on Amazon). I have a 100w HQST panel mounted to a Rhino Vortex rack using some L-brackets that I fabricated.

Components of my setup: (not affiliate links)

Dometic CFX-50w Fridge
DFG Offroad slide
Suaoki G500
HQST 100w panel
Angle brackets for panel mounts
Thumb knobs for panel mounts

When I was researching my system, I found it very difficult to get a good assessment of a number of things that I am going to try to update here in this thread as I learn/discover them for myself. Such things as:

1. How much power will it really draw in a real world scenario?
2. Is a 500WH battery system "enough"?
3. What is the impact of adding a solar panel? What size panel should I get?
4. Is a 50L Fridge the right size?
5. Whats the best way to mount it in a lifted Jeep?
6. What is a good way to wire everything up?


Here are my initial findings, which I will update as I learn more and/or modify my system. I hope this thread becomes a resource for people considering the 50 liter Dometic fridge (or other similar fridges).

Power Draw

Indoor (ideal scenario) shows that the fridge cycles on for 3 minutes every 30 minutes when set to 39 degrees F and the ambient temp is about 70 degrees F. This is without the insulated cover (which I plan to add) and without opening the fridge. When the fridge cycles, the indicated power draw averages about 50 watts during those 3 minutes (off DC and about 58 watts off AC). If my math is right, then this is 2.5 watt hours. Assuming that the cycle rate is the same for 24 hours (it will usually be cooler at night and thus cycle less often) then this is about 120 watt hours every 24 hours, or a little over 20% of the capacity of the Suaoki G500 battery pack I'm using.

Empirically, I've seen similar results in the field, but the biggest difference being that the cycling can occur more frequently with warmer ambient temps and opening the fridge to prepare dinner and grab cold drinks. I've found that if the battery is fully charged on solar until the sun sets to the point where it is no longer charging the battery (around 4:30 pm), and then the fridge is used to make dinner and grab drinks, with an overnight temperature starting around 70 degrees and then dropping to the low 50's, I will see the battery indicator has dropped 2 bars (each representing 20% of the 500 watt hour capacity) but will very quickly recharge to 1 bar, telling me that its just barely past the 20% threshold. I can deduce from this that the fridge is consuming slightly more than 100 watt hours each night. During my weekend testing in the desert, I was able to start charging again at around 8 AM, making for about 15-1/2 hours of operating time without any charging.

Bottom line, after the morning clouds cleared, I was able to top up the battery 100% each morning by the time I was done putting away breakfast and getting ready to explore for the day if we were on a "gentlemen's schedule" (e.g. lazy start). Using the 100w panel in strong sun provides about 50 to 60 watts early in the morning (7 am to 10 am), gradually increasing to 75 watts by 10 am and 90+ watts by noon. On mornings when we want to head out exploring early in the day, I mounted the panel back on the roof of the Jeep and the battery was always 100% charged by the time we got back to camp in the evening while also powering the fridge all day on the trail.

I found that because of the high efficiency and greater throughput of the solar charge controller built into the Suaoki unit, I was MUCH better off using solar versus using the 12v receptacle that I installed in the back of the Jeep to recharge the battery pack. One day using the 12v receptacle, I arrived back at camp in the early afternoon to see that my state of charge had not changed at all, even after about 4 hours on the trail (meaning that the fridge had essentially consumed all the power provided yielding no net gain or loss to the battery). I quickly deployed my solar panel angled to the sun and after a few hours was able to fully charge the battery. Lesson Learned: don't bother with the 12v receptacle - just use the solar panel all the time.

More to come....

Mate I would check the voltage at the battery when the Vehicle is/has been running for about 20 minutes at round 1500rpm and then go and check it at the Socket you had it plugged in to, With out putting my 47L fridge in my vehicle and running the same test it's a bit hard to guess, I did run my little Dometic CDF 18 for 4 days and It never dropped below 100%, Baring in mind the CDF 18 uses less than half of what your CFX 50 uses something like 60w on DC and about 101w on AC, But regardless of the Fridge size my PLB charges faster than the fridge can use it.

Also is your Suaoki an AGM/Lead Acid or is it a Lithium Pack ??

 

[SBSYNCRO]

Mate I would check the voltage at the battery when the Vehicle is/has been running for about 20 minutes at round 1500rpm and then go and check it at the Socket you had it plugged in to, With out putting my 47L fridge in my vehicle and running the same test it's a bit hard to guess, I did run my little Dometic CDF 18 for 4 days and It never dropped below 100%, Baring in mind the CDF 18 uses less than half of what your CFX 50 uses something like 60w on DC and about 101w on AC, But regardless of the Fridge size my PLB charger faster than the fridge can use it.

Also is your Suaoki an AGM/Lead Acid or is it a Lithium Pack ??

The Suaoki is a Li-Ion battery pack. As to the voltage, i've tested it out and it reads the same in all three locations I've tested with the engine warmed up and running at 1500 or so RPM - at the battery, at the dash (where I have a voltmeter installed) and then at the end of the lead that comes from the back side of the dash-mounted voltmeter and runs to the rear receptacle. I have it fused and wired for a 10 amp circuit, but unfortunately the Suaoki appears to be limited to 3.5 amps on the 6.5mm DC input which equates to a max of roughly 45 watts. My guess is that it did actually provide some net charging benefit, but because the battery icon only measures in 20% increments, it wasn't enough to lift it up over to the next hurdle, and therefore wasn't apparent. To bump to the next bar on the power icon could potentially require as much as 100 watt hours of net power above the fridge usage, and after 3 hours on the trail, I doubt that at a charge rate max of 45 watts, its likely it didn't deliver enough.

 

[67cj5]

The Suaoki is a Li-Ion battery pack. As to the voltage, i've tested it out and it reads the same in all three locations I've tested with the engine warmed up and running at 1500 or so RPM - at the battery, at the dash (where I have a voltmeter installed) and then at the end of the lead that comes from the back side of the dash-mounted voltmeter and runs to the rear receptacle. I have it fused and wired for a 10 amp circuit, but unfortunately the Suaoki appears to be limited to 3.5 amps on the 6.5mm DC input which equates to a max of roughly 45 watts. My guess is that it did actually provide some net charging benefit, but because the battery icon only measures in 20% increments, it wasn't enough to lift it up over to the next hurdle, and therefore wasn't apparent. To bump to the next bar on the power icon could potentially require as much as 100 watt hours of net power above the fridge usage, and after 3 hours on the trail, I doubt that at a charge rate max of 45 watts, its likely it didn't deliver enough.

Ok well some thing is not right, Any ways I am going to run a test running my ARB 47L from a 12v Deep Cycle Lead Acid Battery But with the little NOCO 3.5 Ah Charger hooked up to the Battery and see if that is enough to run the fridge and balance out the battery at the same time So Check back with me in a few hours and we'll see if it matches yours or works better or if it doesn't work at all,

In theory It should work because the Fridge is not going to chew 3.5Ah per hour even if it is running @ 5Ah,

 

[SBSYNCRO]

Is the Noco a dc to dc charger or will you be testing it off an ac inverter? (Is that 3.5 amps at 12v DC?)

 

[67cj5]

Is the Noco a dc to dc charger or will you be testing it off an ac inverter? (Is that 3.5 amps at 12v DC?)

No it's not but that does not matter because it's about seeing if 3.5Ah is enough to keep the battery topped up while it is running the fridge.

 

[67cj5]

Well the little 3.5Ah NOCO held it's own but the down side is that smart chargers don't put the full amount of power back in like a normal chargers does,

After 5 hours I swapped the NOCO for a very old 4Ah Charger and it was putting in between 2 to 2 and a half amps and the battery was full after about 30 minutes So basing it on that the NOCO did do the job because the 4Ah Charger had to be turned off after 30 mins,

So for this I think there are 2 issues you have going on with your gear baring in mind I was using a Lead Acid battery which charges a lot slower than your lithium pack or should do by rights, Note I also had my ARB set 4* Colder than what you had your CFX set to.

Issue One I would say your fridge is cycling wrong where it is coming ON too Often, IE Mine runs for about 13m 45s and then it shuts off for 2 hours 1 minute to 2 hours 5 minutes and then it repeats it's run cycle again, Now you might be thinking that mine is running 4 times longer Or Twice as long as yours is per hour but the fact is yours runs for 3 minutes and shuts off for 30 and the ON again for 3 minutes and off for 30 minutes again and It is the way it cycles which is why it is not charging because when most fridges cycle they run for between 9 and 20 minutes and then they shut off and the battery recovers about 0.20 to 0.30v Also when it is hooked up to a charger those Long OFF times allow the Charger to put back the charge in to the battery "But " while yours is cycling on and off every 30 minutes it is not staying off long enough to put back the charge in to the battery So it never quite gets completely topped up where as mine is coming on for 13m 45s/ 14 minutes it is staying off for over 2 hours and even with a little 4Ah clamped on to a 115 Lead Acid Battery it is still maxing out putting back the power the fridge has used.

At first I thought your run times were caused by how you are packing the fridge, But there again My little Dometic CDF 18 does exactly the same as your CFX 50 does But both of my ARB's will run for 10 / 15 / 20 minutes and then shut off for something like 50 minutes to a couple of hours depending on how it's packed, The way it is packed at the moment it is running for 13 to 14 minutes and it is shutting for over 2 hours, In one way the Dometic Run Cycles allow for a more even Temperatures between it's On and OFF cycles, Where as The ARB's will run a bit longer and then shut off for a very long time,

With the way the Dometics cycle you need a powerful / fast charging system IE something like the PLB 40, where as with my ARB's can adapt to a wide range of battery systems like a Lead Acid battery with a 4 Ah Charger or the PLB 40 and a Cigar Socket either way No matter what set up I use the Off times allow me to put back a lot of power and I am sure that I could even get away with using a 2Ah Charger with the lead acid battery and it would still run the fridge and charge the battery during the On and Off Cycles,

Issue Number 2 ) I think that the weakest link in your setup is that battery pack you are using Where it would work with my ARB because of how it Cycles with your CFX 50 due to it's short Cycle rates is not a good match with your battery pack,

Thing is Dometic made your fridge and they also made the PLB 40 and they made the PLB 40 to match their CFX range of Fridges and it just so happens that the PLB works with my ARB No matter if I am Charging the PLB with the Supplied AC adapter or Via a 12v Cigar Socket,

When we spoke in another thread about these Lithium Battery packs I did mention my reasons for my Choice of battery packs but you had your heart set on the Suaoki, Thing is you have a good fridge and being a Dometic I would of chosen the PLB,

Anyways all is not lost, maybe you can get a PLB and then you will have the Suaoki as a backup or use it for running lights and phones and other gadgets etc,

Hope that helps.