Dometic CFX3 35 Cooler: Impact to R1T battery level after 24 HR of 120V connection

[EVTrukHog]

Don't know about that one specifically, but my Jackery 240 charges at 60w plugged into a standard house outlet. I would assume something similar for the PLB40. That means the Jackery charges 0-100% in 4 hours (240wh).

My operation will be to run the fridge on the truck's 12v in the cabin (I pass it through into the gear tunnel outlet) while driving (no extraordinary losses because the truck is already running/awake and I'm on 12v), then switch to the Jackery at camp/destination so that the truck can sleep.

I'd love to see an easy mod that installs a 12V outlet in the bed of the truck - which is where my cooler stays.

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[DJG]

I'd love to see an easy mod that installs a 12V outlet in the bed of the truck - which is where my cooler stays.

My guess is that there is no easy mod, as there is a reason not a single truck on the market has one from the factory, nor have I ever seen one modded to add one.

Way easier and likely cheaper to just keep a power station in the bed with the fridge. Or you could see if the gear tunnel door will close with a 12v cable run out of it into the bed....

 

[EVTrukHog]

This may not be interesting to anyone but me, but I did some additional testing tonight. My end game is to determine how long I can keep my CFX3 cooler electrified while off the grid.

The Dometic CFX3 35 takes about 50% of the PLB40 portable battery’s SOC per 24 hour of cooling period. The R1T 120v outlet will recharge the PLB40 from 0% to 100% in just under 6 hours and drain about 3% SOC from R1T.

Back to the original question: I can keep cooler running off fully charged PLB40 for 48 hours which would cover most weekend trips. For an extended 72 hour trip, I just need to plug the PLB40 into Rivian 120v outlet for about 3 hours and it will give me another 24 hours of cooler while just using about 1.5% Of R1T SOC. My portable solar panel will help offset some of the dependency on the R1T for extended trips. I can live with these results.

I’m sure many of you could have calculated these results with electrical formulas, but electrical engineering is not my native language. YMMV.

 

[VSG]

Since I normally lose 1%-2% of SOC in a 24 hour period, I'd attribute an approximate 6% SOC discharge due to the cooler. While this may not be a linear discharge, you could approximate about 1% SOC discharge every 4 hours of being connected to the 120V supply of the R1T. YMMV.

My end game is to determine how long I can keep my CFX3 cooler electrified while off the grid.

Then I think you're going about this wrong.

The cooler takes very little power - far less than what you are reporting. But that's probably because your constant draw doesn't allow the Rivian to go to sleep. All that extra power is from the Rivian being awake for 24 hours, not from the cooler.

I suggest putting your vehicle in Camp Mode so you can use the outlet *and* let your Rivian sleep. That will give you a more realistic number.

 

[EVTrukHog]

Then I think you're going about this wrong.

The cooler takes very little power - far less than what you are reporting. But that's probably because your constant draw doesn't allow the Rivian to go to sleep. All that extra power is from the Rivian being awake for 24 hours, not from the cooler.

I suggest putting your vehicle in Camp Mode so you can use the outlet *and* let your Rivian sleep. That will give you a more realistic number.

Truck was asleep, but 120V outlet left "on" for 24 hour period. As several posts identified, I suspect the SOC discharge was due to power inverter being on during that time. No known way to keep this from happening while using the 120V plug.

 

[VSG]

1% normal drain. 1% for 50W cooler running constantly for 24 hours. 5% loss due to inverter? That means the inverter is consuming 250W continuous in addition to the 50W power it provides? Does not compute. Inverters are >90% efficient, not <20%.

 

[VSG]

No known way to keep this from happening while using the 120V plug.

Again, did you try Camp Mode?

 

[DJG]

Again, did you try Camp Mode?

Camp Mode doesn't do what you think it does. There actually isn't a mode, it's a menu of several options. The options for power usage are Stay Off, Normal and Stay On.

To conserve power, you'd select Stay Off, but that is counterproductive in this case because it shuts off the outlets. Normal changes nothing and it behaves as it always does. Stay On just keeps things like the screen and HVAC on for when you are sleeping in the vehicle. Outlets are still toggled on/off separately and are subject to a 24 hour max on time (though you can cycle them off and back on to restart that clock at any time).

 

[DJG]

1% normal drain. 1% for 50W cooler running constantly for 24 hours. 5% loss due to inverter? That means the inverter is consuming 250W continuous in addition to the 50W power it provides? Does not compute. Inverters are >90% efficient, not <20%.

It's actually even more pronounced. The fridge doesn't use an average of 50w, that's the max/surge draw when actively cooling. Depending on the ambient temp, the average draw is closer to 10-12w on 12v power.

Yes, keeping the inverter on requires keeping a lot of other systems on, which all adds up to the additional draw.

 

[DJG]

I suggest putting your vehicle in Camp Mode so you can use the outlet *and* let your Rivian sleep. That will give you a more realistic number.

These things are not possible. You cannot power outlets and let the vehicle sleep. The former requires the vehicle not be asleep by nature. The power conserve Camp Mode option shuts down all outlets and you have to wake the vehicle and turn it off to use them.

 

[VSG]

It's actually even more pronounced. The fridge doesn't use an average of 50w, that's the max/surge draw when actively cooling. Depending on the ambient temp, the average draw is closer to 10-12w on 12v power.

Yes, keeping the inverter on requires keeping a lot of other systems on, which all adds up to the additional draw.

Yes, this is what I have been saying. My numbers were back-of-the-envelope worst case overestimates to demonstrate that the OPs claim that the cooler is responsible for 6% battery drain is just wrong. And attributing the usage to the inverter is also just wrong.

If I had used 10-12W in the calculation, then someone would argue "well that depends, if it's hot out it could use a lot more" etc. The point of using the max 50W in the calculation is that it is an upper limit, so my conclusion holds regardless of what the "actual" average draw is.

The cooler doesn't take a lot of power, the inverter doesn't take a lot of power. Together they can account for about a 1% extra drain, worst case. The bulk of the observed power loss is because the vehicle is awake the whole time and does not have a chance to go to sleep - it is doing many things other than running the cooler and the inverter, and it is those other things which are the cause of the power drain. In fact, it doesn't matter what you plug in - if you had a 4W night light running in the outlet you would still see a lot of drain. Again, this has nothing to do with the device you're using, and tells you nothing about the Dometic cooler

Rivian's software updates have been improving the "vampire" drain, in large part by reducing the amount of time the vehicle stays awake. One of the specific goals of Camp Mode was to reduce battery usage when camping. Whether it has met this goal I don't know, but that's what the intention was. There is really no need for the vehicle to be fully awake just for the inverter to function, so if the current implementation of Camp Mode doesn't allow the vehicle to go to sleep when the outlets are active then that's something that needs to be improved in Camp Mode. Perhaps that's the take-away here.

 

[DJG]

Yes, this is what I have been saying. My numbers were back-of-the-envelope worst case overestimates to demonstrate that the OPs claim that the cooler is responsible for 6% battery drain is just wrong. And attributing the usage to the inverter is also just wrong.

If I had used 10-12W in the calculation, then someone would argue "well that depends, if it's hot out it could use a lot more" etc. The point of using the max 50W in the calculation is that it is an upper limit, so my conclusion holds regardless of what the "actual" average draw is.

The cooler doesn't take a lot of power, the inverter doesn't take a lot of power. Together they can account for about a 1% extra drain, worst case. The bulk of the observed power loss is because the vehicle is awake the whole time and does not have a chance to go to sleep - it is doing many things other than running the cooler and the inverter, and it is those other things which are the cause of the power drain. In fact, it doesn't matter what you plug in - if you had a 4W night light running in the outlet you would still see a lot of drain. Again, this has nothing to do with the device you're using, and tells you nothing about the Dometic cooler

Rivian's software updates have been improving the "vampire" drain, in large part by reducing the amount of time the vehicle stays awake. One of the specific goals of Camp Mode was to reduce battery usage when camping. Whether it has met this goal I don't know, but that's what the intention was. There is really no need for the vehicle to be fully awake just for the inverter to function, so if the current implementation of Camp Mode doesn't allow the vehicle to go to sleep when the outlets are active then that's something that needs to be improved in Camp Mode. Perhaps that's the take-away here.

Gotcha. Camp Mode is not intended to address power usage while still utilizing the outlets. It's made for situations where you want to power down the entire vehicle and not have anything plugged in. The vehicle is not physically capable of running the invertor without having other systems on, that just is what it is and is what people will have to live with to run things continuously like fridges.

That's why the best solution if range is a consideration is to run a fridge on a portable battery while parked/at camp, particularly if you are not planning to be stationary for several days and can recharge the portable battery while driving, or if you utilize solar to recharge it during the day.

However, I am intrigued that the Optima crew included a new 12v system in their build for SEMA, so perhaps that is one thing they were attempting to solve for, with a way to access that power directly without going through the vehicle systems (but that may not ultimately be much different from what I just described above with a portable battery).

 

[VSG]

However, I am intrigued that the Optima crew included a new 12v system in their build for SEMA, so perhaps that is one thing they were attempting to solve for, with a way to access that power directly without going through the vehicle systems.

I think they were primarily thinking about their solar and battery storage, and being able to power other things on their trailer with that regardless of the tow vehicle - it would have taken a lot more effort to fully integrate that stuff into any EV, and the trailer is a product they can sell unlike a custom integration which is more of a service.

 

[DJG]

I think they were primarily thinking about their solar and battery storage, and being able to power other things on their trailer with that regardless of the tow vehicle - it would have taken a lot more effort to fully integrate that stuff into any EV, and the trailer is a product they can sell unlike a custom integration which is more of a service.

No, this is separate from the trailer entirely. They added their own batteries in the frunk (2x 19ah or about 450wh total lithium) for powering auxiliary devices. If the OEM are indeed lead acid, that may give the answer, as they are not deep cycle and not well suited for running devices like fridges for long periods of stationary use.

At 3:30

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