Dometix CFX 50W Normal or Problem?

[jg45]

Recap, I'm on an Optima red top AGM group 35 battery. My voltage meter and the voltages reported by the fridge are listed in my post above. I have had the battery tested at two different stores. Both showed resting voltage of 12.67v and load test showed over 900cca (battery rated for 720cca). So perhaps my Fluke meter is off. But then so is the fridge itself as it reads even lower. I may end up getting a different battery, or a separate battery for fridge with engine off. But I still suspect that the fridge voltage reading is lower than actual voltage and I will therefore be limited to only using the lowest setting on the battery protection system.

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[sonoronos]

I just read carefully through all your posts, and this is what I think you're saying:

1. You used a DMM to measure the battery voltage at the terminals.
2. You compared this voltage in the DMM to the mobile app that instruments what the refrigerator think is the battery voltage.
3. These two values do not agree, and now you're trying to figure out why.

I think it's safe to say that the DMM (no matter what DMM you have) across the battery terminals is going to be the most accurate measurement of the battery voltage.

I think it's safe to say that the fridge's measurement of voltage is done using an unknown method, and you can really only guess at what it's measuring. This seems more likely to me given my experience with consumer electronics.

You could measure the voltage at the fridge by tapping into your wires and using your DMM there.

 

[67cj5]

I'd bet most running fridges are on AGM

AGM are great for using in Rough terrain etc, but there is not much point in changing to lithium at present due to the cost and most folks don't need them and having them is more about bragging rights around the campfire than need, My last flooded wet lead acid deep cycle battery was just 2 months short from being 10 years old and the only reason it died was because I kept starting the truck twice a week for about 20 minutes to run one of my compressors, If I had the time to take it on a long run each time most likely it would still be going today,

Lithium are pointless for most peoples needs, and so what if they last for 10 years plus, A lead acid will do that if it is well maintained and at a 10th of the price. and even if they don't you can but 10 deep cycle batteries for the price of a lithium battery, So lithium are not cost effective. And AGM are the better for off road vehicles and the long term usage etc.

 

[67cj5]

Recap, I'm on an Optima red top AGM group 35 battery. My voltage meter and the voltages reported by the fridge are listed in my post above. I have had the battery tested at two different stores. Both showed resting voltage of 12.67v and load test showed over 900cca (battery rated for 720cca). So perhaps my Fluke meter is off. But then so is the fridge itself as it reads even lower. I may end up getting a different battery, or a separate battery for fridge with engine off. But I still suspect that the fridge voltage reading is lower than actual voltage and I will therefore be limited to only using the lowest setting on the battery protection system.

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Sounds like a good Idea Mate, At 12.67v sounds like the battery is where it should be under normal driving condition.

Good thing is at leased now you know where your battery is at, well done for sticking with it,

 

[dcg141]

I have a CFX65 and use a group 35 Northstar AGM with a 25 Amp Redarc DC to DC charger. I have a run of about 12 feet of 10 gauge cable. The threshold is set to low on the unit. Its a new setup in my GX 470 and I have only used it on one trip so far. I was at a campsite with AC but I did not use it all weekend. My fridge ran for 24 hours wo any recharge on the battery with no issues. I was kayaking so every day we ran the vehicle and the 25 amp charger would bring the battery back to full charge with about a 30 minute drive. Not really sure where the limit to shutdown is on my setup. Also since the drive everyday brought the battery back up I never hooked up the solar panel either. My Redarc is a dual input with a MPPT solar charger. Normally out of my panel I can get 4-5 amps total with good sun with about 50-60 watts. It seems the 10 gauge is plenty of wire. I'm sure I would gain some efficiency with 8 or 6 gauge but I don't think it would be enough to offset the cost and trouble of running cable that large.

 

[vtsoundman]

I doubt your fluke is off unless it was damaged in someway.

A group 35 is a 60ah battery - so figure on 30ah useable for Max life. Most Dometics pull 0.5-1ah on a nominal day with minimal open/close. The later the fridge, the greater the draw. I've modded mine a bit, so usually see 0.5ah on my CFX65 DZ

Since you'll be going in/out of your fridge and may be warmer thabln their guidelines (pushing 1.5 ah or more if you're really pushing it), I wouldn't try to push more than 24 hours out of your battery.

18ft on the ARB kit - what guage? If #12, that wire is too small. Are you also using the Dometic wire too (I think it's #14) ? That wire is pretty small and should be kept short.

Normally, 18' of #10 should be fine for a fridge assuming you have one ATC and one Maxi fuse between you and the battery have solid crimped, and a decent disconnects/plugs. NO cig lighter style. Don't forget, that you need to double it - so you will have 36' of wire.

If your batteries are fresh/good, the issue is most likely a poor connection. Find a local ground to the fridge and cut/tie it there...this will reduce the overall loses.

12.46 on a freshly charged battery is likely due to another load. Having a key in the ignition, the emissions, radio, pcm, fuel injection systems, etc often will consume current for several minutes after the vehicle is off - all of these may continue to draw current.

A battery can take up to 24hrs to get to a resting voltage...or about 1 min with your headlights on. This will bleed off the surface charge from 13.x down to about 12.7 or 12.8V.

To trouble shoot voltage drop,measure the voltage from the pos battery terminal to the pos fridge terminal while it is running....that will tell you the total series voltage loss for half the circuit. The other half will be the ground return. If you meaure 0.65V on the pos, your total loss will be about 1.3V.

The other issue is your alternator. I think I read you have a AGM - you need 14.5 to 14.7 to properly charge that battery. (It can be as high as 15V or more when cold). If your alternator can produce 14.2V or so, you'll be fine as long as you put an aux charger on that battery from time to time.

 

[jg45]

I doubt your fluke is off unless it was damaged in someway.

A group 35 is a 60ah battery - so figure on 30ah useable for Max life. Most Dometics pull 0.5-1ah on a nominal day with minimal open/close. The later the fridge, the greater the draw. I've modded mine a bit, so usually see 0.5ah on my CFX65 DZ

Since you'll be going in/out of your fridge and may be warmer thabln their guidelines (pushing 1.5 ah or more if you're really pushing it), I wouldn't try to push more than 24 hours out of your battery.

18ft on the ARB kit - what guage? If #12, that wire is too small. Are you also using the Dometic wire too (I think it's #14) ? That wire is pretty small and should be kept short.

Normally, 18' of #10 should be fine for a fridge assuming you have one ATC and one Maxi fuse between you and the battery have solid crimped, and a decent disconnects/plugs. NO cig lighter style. Don't forget, that you need to double it - so you will have 36' of wire.

If your batteries are fresh/good, the issue is most likely a poor connection. Find a local ground to the fridge and cut/tie it there...this will reduce the overall loses.

12.46 on a freshly charged battery is likely due to another load. Having a key in the ignition, the emissions, radio, pcm, fuel injection systems, etc often will consume current for several minutes after the vehicle is off - all of these may continue to draw current.

A battery can take up to 24hrs to get to a resting voltage...or about 1 min with your headlights on. This will bleed off the surface charge from 13.x down to about 12.7 or 12.8V.

To trouble shoot voltage drop,measure the voltage from the pos battery terminal to the pos fridge terminal while it is running....that will tell you the total series voltage loss for half the circuit. The other half will be the ground return. If you meaure 0.65V on the pos, your total loss will be about 1.3V.

The other issue is your alternator. I think I read you have a AGM - you need 14.5 to 14.7 to properly charge that battery. (It can be as high as 15V or more when cold). If your alternator can produce 14.2V or so, you'll be fine as long as you put an aux charger on that battery from time to time.

The ARB wiring kit is 10 gauge wire. The Optima is a 44ah battery. The plug looks like a cig lighter, but is not. It has two prongs inside that insert into matching slots in the dometic cable (when you unscrew the cig adapter). It's a good solid locking connection. I have read from several sources to run the ground back to the battery directly and not to ground to the chassis. That's how the ARB kit is put together as well.
Just seems silly for Dometic to have three levels of battery protection, but only the lowest is useful due to the way the fridge reads voltage.

 

[e60ral]

AGM are great for using in Rough terrain etc, but there is not much point in changing to lithium at present due to the cost and most folks don't need them and having them is more about bragging rights around the campfire than need, My last flooded wet lead acid deep cycle battery was just 2 months short from being 10 years old and the only reason it died was because I kept starting the truck twice a week for about 20 minutes to run one of my compressors, If I had the time to take it on a long run each time most likely it would still be going today,

Lithium are pointless for most peoples needs, and so what if they last for 10 years plus, A lead acid will do that if it is well maintained and at a 10th of the price. and even if they don't you can but 10 deep cycle batteries for the price of a lithium battery, So lithium are not cost effective. And AGM are the better for off road vehicles and the long term usage etc.

who said anything about lithium? that looks like a flooded lead acid chart, not an AGM chart, and I bet most fridges are on AGM batteries.

for example that chart has 100%- 12.7 V, 75%- 12.4 V, 50%- 12.2 v, 25%- 12.00 V, 0%- 11.9V
AGM battery is 100%- 12.8 or higher V, 75%- 12.6 V, 50%- 12.3 V, 25%- 12.00 V, 0%- 11.8V
and Gel would be slightly higher 100%- 12.85 or higher V, 75%- 12.65 V, 50%- 12.35 V, 25%- 12.00V, 0%- 11.8V

 

[67cj5]

who said anything about lithium? that looks like a flooded lead acid chart, not an AGM chart, and I bet most fridges are on AGM batteries.

for example that chart has 100%- 12.7 V, 75%- 12.4 V, 50%- 12.2 v, 25%- 12.00 V, 0%- 11.9V
AGM battery is 100%- 12.8 or higher V, 75%- 12.6 V, 50%- 12.3 V, 25%- 12.00 V, 0%- 11.8V
and Gel would be slightly higher 100%- 12.85 or higher V, 75%- 12.65 V, 50%- 12.35 V, 25%- 12.00V, 0%- 11.8V

I said about Lithium Batteries, fact is they are a money pit and not worth the cost, and most people who buy them it is more of a matter of bragging rites than Need.

Last month I ran my ARB 50Qt fridge for 6 Days 8 hours from the same battery and the Voltage was still well above 12 Volts before I turned it off and I only stopped it then just to make sure that I stayed well above the deep cycle range of the Battery and it would of kept going for 8 or 9 days until the Battery protection would have kicked in if I had not stopped it.

Well my Lead Acid batteries read between 13.32v after a few hours off the charger and about 6 days later they read about 12.93v+ which kind of shoots all of those figures in the foot, Today I have been running a small TV from a Lead Acid Deep Cycle battery for the last 6 hours and the Battery is still reading 12.97 / 12.98 Volts.

 

[JK47]

I have a Dometic CFX-40W in my 2018 Jeep JL and also use the the same ARB wiring kit (roughly18' from battery to wiring as well). I did buy the Dometic insulation cover and I have the fridge set on medium voltage auto off, and can get 3 full days of cooling set at 36F/37F without turning my Jeep on or using Solar power, with outside tempeprature in the upper 70' low 80's. I do leave the windows open a crack to prevent the interior of the Jeep from becoming too much of an oven.




40 bottles of Bud stuffed, hooked up to AC.

 

[jg45]

I have a Dometic CFX-40W in my 2018 Jeep JL and also use the the same ARB wiring kit (roughly18' from battery to wiring as well). I did buy the Dometic insulation cover and I have the fridge set on medium voltage auto off, and can get 3 full days of cooling set at 36F/37F without turning my Jeep on or using Solar power, with outside tempeprature in the upper 70' low 80's. I do leave the windows open a crack to prevent the interior of the Jeep from becoming too much of an oven.
View attachment 524630
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40 bottles of Bud stuffed, hooked up to AC.
View attachment 524633

What kind of battery set up are you running and what does your fridge show for voltage in the app?

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[mk4]

You probably have a faulty fridge. There's probably failing component that is causing excessive voltage drop. You should see about 0.5 V drop with the compressor running. I would contact Dometic and get it replaced.

Are you getting a single blinking error led?

Try starting the fridge with the car running.

 

[JK47]

What kind of battery set up are you running and what does your fridge show for voltage in the app?

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The ARB kit is wired to my stock battery, and I have never checked voltage with the wifi app.