Efficiency Vs. Temperature: Data Update, Conserve Only Helps in Warm Temps.

[Budman]

Thanks for sharing this. What are your climate controls set at? Also, on the route what is the change in elevation?

Hi 240vPlug;

The elevation at home is around 800 ft and at the cabin around 1400 ft. A 600 ft change with most of that coming in the last 30 miles. If I squint really hard at the data I can kinda see a difference in travel direction from the net elevation change but it is subtle.

I keep the cabin temp at 70 to 72 deg. I use the cabin heater freely along with heated seats and stearing wheel. I don't do anything special to try and increase range, just drive and be comfortable.

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[R1Tom]

Was thinking just the opposite. Since the Enduro has more efficient oil-bath cooling, and the heat transfer appears more efficient, it is likely to use less energy keeping the battery warm (less system loss).

Since the system isn't intentionally rejecting any heat, the loss of efficiency energy has to go somewhere, so for what you say to be true, that would mean the actual drive case would have to be hot and rejecting that loss of efficiency heat. I don't think that is the case. Most of the heat is being used to heat the batteries. The only time efficiency would come into play is if mechanical cooling is taking place (i.e. cooling g fan and fluid cooler) and since all heat is desired in the battery pack, that isn't case.

Think of it like an old incandescent light bulb in a room with electric resistive baseboards. Sure...the LED lights would be more efficient but....now the baseboards have to run more to offset.

In this case, the oil bath is more "efficient' at moving heat than air, so the internal temps in QM are likely higher, but that doesn't take more energy to make happen than the lower temps, moving same amount of desired energy into the coolant lines, at lower temps, in the QM. If you put "x" watts into air insulated windings, yes they will get hotter, then same "x" watts into the oil bathed windings. But same "x".

 

[R.I.P.]

Since the system isn't intentionally rejecting any heat, the loss of efficiency energy has to go somewhere, so for what you say to be true, that would mean the actual drive case would have to be hot and rejecting that loss of efficiency heat. I don't think that is the case. Most of the heat is being used to heat the batteries. The only time efficiency would come into play is if mechanical cooling is taking place (i.e. cooling g fan and fluid cooler) and since all heat is desired in the battery pack, that isn't case.

Think of it like an old incandescent light bulb in a room with electric resistive baseboards. Sure...the LED lights would be more efficient but....now the baseboards have to run more to offset.

In this case, the oil bath is more "efficient' at moving heat than air, so the internal temps in QM are likely higher, but that doesn't take more energy to make happen than the lower temps, moving same amount of desired energy into the coolant lines, at lower temps, in the QM. If you put "x" watts into air insulated windings, yes they will get hotter, then same "x" watts into the oil bathed windings. But same "x".

Think about it. A lot of heat being created at the armature (center), with the QM trying to scavenge it off the case; which of course is air-gapped. Meanwhile, the shafts and gearing are directly connected to the heated source; wicking all that heat directly out into the cold air.

The Enduro is collecting it at the source and moving it toward the battery.

It is pretty clear by just looking at the design, but further evidence can be found on your dash. An Enduro is getting enough heat to make the battery happy by heating one motor to 120F. Quads can be seen super-heating all 4 to get similar results.

Rivian learned a lot from the Bosch experiment, and is making the trucks better. Rejoice.
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[R1Tom]

Think about it. A lot of heat being created at the armature (center), with the QM trying to scavenge it off the case; which of course is air-gapped. Meanwhile, the shafts and gearing are directly connected to the heated source; wicking all that heat directly out into the cold air.

The Enduro is collecting it at the source and moving it toward the battery.

It is pretty clear by just looking at the design, but further evidence can be found on your dash. An Enduro is getting enough heat to make the battery happy by heating one motor to 120F. Quads can be seen super-heating all 4 to get similar results.

Rivian learned a lot from the Bosch experiment, and is making the trucks better. Rejoice.
?

I don't think Bosch was an experiment. It was a get to market quicker move which added cost, so with time, lower costs thru vertical integration drives the change.

Just because the sensor in the QM is located in a thermal location that shows higher temps, does not mean that the DM is more efficient. As long as that heat is making it to coolant, and not atmosphere, it has zero effect on efficiency. Sure...a very minor amount might be in a slightly elevated case temp in the QM, but it also maybe more elevated in the DM, since all that oil is carrying the heat to the case more effectively and transferring it the case. Effective...not efficient. The air being an insulator may actually be transferring more of the heat into the coolant and the oil maybe transferring it to the case.

One could argue that oil bath is consuming some energy to move too. Air offers much less internal resistance.

I think you are mistaking the elevated temps in the displays on the QM to mean energy and in this case it is energy we are concerned about and not temps.

 

[R.I.P.]

I don't think Bosch was an experiment. It was a get to market quicker move which added cost, so with time, lower costs thru vertical integration drives the change.

Just because the sensor in the QM is located in a thermal location that shows higher temps, does not mean that the DM is more efficient. As long as that heat is making it to coolant, and not atmosphere, it has zero effect on efficiency. Sure...a very minor amount might be in a slightly elevated case temp in the QM, but it also maybe more elevated in the DM, since all that oil is carrying the heat to the case more effectively and transferring it the case. Effective...not efficient. The air being an insulator may actually be transferring more of the heat into the coolant and the oil maybe transferring it to the case.

One could argue that oil bath is consuming some energy to move too. Air offers much less internal resistance.

I think you are mistaking the elevated temps in the displays on the QM to mean energy and in this case it is energy we are concerned about and not temps.

So... Please... No offence meant... But this statement suggests you may not have a good understanding of how this works... i.e. "conductor vs insulator"...

"The air being an insulator may actually be transferring more of the heat into the coolant"

All good tho. I am not trying to convince you if anything, just making observations.
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[R1Tom]

So... Please... No offence meant... But this statement suggests you may not have a good understanding of how this works... i.e. "conductor vs insulator"...

"The air being an insulator may actually be transferring more of the heat into the coolant"

All good tho. I am not trying to convince you if anything, just making observations.
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No offense taken. I am a mechanical engineer with over 30 years in the heat transfer field, so I am just trying to explain, and probably poorly.

What I was saying in that statement, is that if the coolant surfaces are somewhere thermally in the case, it is possible in the QM, that the heat is actually being transfered to the coolant to a greater degree and not actually to the outside surfaces of the case, potentially more effectively than in the oil bath DM case, as the oil is a more effective conductor and thus bathing all the interior surfaces with that temperature. I am not saying that is the situation, but it is possible.

I guess ultimately I am just saying that elevated temps at the sensors in QM doesn't mean any added energy is being lost from the system necessarily. Alot more has to be known to make that jump.

My personal thought is that the added overall efficiency of the DM has to do alot more with the rear being defaulted to effectively the QM conserve more, than anything else.

 

[RivRyan]

>one month of ownership and we like the XC40 so far. Does not qualify for tax credit so it is not the best value out there but it is a very nice, solid, comfortable car that fits my petite wife better than the R1T. We cross shopped the Model Y but quickly rejected it after a short test drive. A good value but oh so bland.

Thanks. We're looking at a VW ID-4 for my wife for similar reasons. Tesla was on our list till recently. My wife is Jewish and Musk's recent ugly comments scratched his company from consideration. Dude is beyond the pale.

I'd like to get a Rivian, but the only reason to rush would be the tax incentive we'll no longer qualify for as of Jan. 1. Her vehicle needs replacement worse, and we're going to need to ease into EV ownership. We have a 1-car garage so we can't just charge two vehicles nightly. The electrician comes Thursday. Understanding winter charge-economy will be important to making this work.

 

[PsyTrance]

First post here.
I have to say: what a dumpster fire of egos not knowing anything about thermodynamics, electrical engineering and physics yet confidently posting all kinds of explanations while ridiculing others.

It’s just silly. Alas, I’m a bit disappointed.

 

[mkhuffman]

First post here.
I have to say: what a dumpster fire of egos not knowing anything about thermodynamics, electrical engineering and physics yet confidently posting all kinds of explanations while ridiculing others.

It’s just silly. Alas, I’m a bit disappointed.

Your first post is an insult? Way to start off, dude. Maybe instead of insulting others you could take the time to post something of value.

 

[elektrode]

I think you are mistaking the elevated temps in the displays on the QM to mean energy and in this case it is energy we are concerned about and not temps.

Hmmm… on a recent trip, during battery preconditioning, my QM motor temps were correlated to pretty bad efficiency. As soon as the temps raised, the efficiency fell.

Something inefficient was happening. All purpose mode, most likely lowered (auto height)

It could be that I started climbing at the same moment in time, or that the wind picked up, but the orange light “on” => efficiency “not green” was hard to ignore.

Heat is the desired side effect of whatever is going on and loss of efficiency is a non-desirable side effect trade off.

 

[PsyTrance]

Your first post is an insult? Way to start off, dude. Maybe instead of insulting others you could take the time to post something of value.

Clearly not a culture fit for me. It’s the explicit failed attempts of one-upping each other while bragging about it that led me to write this. ‘nuff said: I’m not adding any value here.

thanks to the OP for going through this data collection exercise. Love the confidence intervals! (Gaussian Processes? I bet we could emulate all kinds of things if we pooled our data)

cheers.

 

[PsyTrance]

Also: OP looks like there is a discontinuity there. One maybe could add a discontinuity kernel to learn at which temperatures Rivian built in strategy changes.

My guess is that it could be an integer value on the Celsius scale.

 

[R1Tom]

Hmmm… on a recent trip, during battery preconditioning, my QM motor temps were correlated to pretty bad efficiency. As soon as the temps raised, the efficiency fell.

Something inefficient was happening. All purpose mode, most likely lowered (auto height)

It could be that I started climbing at the same moment in time, or that the wind picked up, but the orange light “on” => efficiency “not green” was hard to ignore.

Heat is the desired side effect of whatever is going on and loss of efficiency is a non-desirable side effect trade off.

Yes...you were consuming energy to heat your battery pack. The same or similar amount of energy the DM would need to consume to do the same amount of heating (work) of the battery pack. Other than some fairly small, potential(and I say potential since we don't know enough of the equation)loss to environment thru the physical case of the QM more than DM as some have speculated, it will be pretty similar. The cases would have to get physically pretty hot to make any substantial difference and I don't think they do.

 

[Martyr]

Posting the latest findings from this large data set I'm acquiring.

Travel conditions: 165 mile trip on a mix of 70 mph interstate and 55 mph rural highways with several traffic lights and small town slowdowns. I travel this route repeatedly from my home near Minneapolis, MN to my cabin near Hayward, WI. I only record the data when temperature gradients during the trip is <8 deg and winds < 15 mph.

Vehicle: 2022 R1T Quad Motor, VIN 8xxx. 21" road tires.

Drive Mode: Some trips in Conserve mode at "Low" ride height and some trips in All Purpose at "Standard" ride height.

Results: Efficiency is a very predicable function of temperature when traveling in conserve mode. In All purpose Mode the behavior is a bit odd but gives the same efficiency as conserve mode in temperatures below 40 Deg F. Conserve mode results in better efficiency only temperatures warmer than ~50 deg F.
(NOTE: I am not claiming you will see similar efficiency data in conditions other than my use case of mixed freeway and rural driving).


Why is this behavior occurring? One guess is that based on the new gauge display, the battery seems to be kept around 50 to 55 deg F. In colder temperatures the motors are working to keep the pack warm so any efficiency benefit that comes from shutting down 2 motors is lost by the extra energy needed to keep the pack at 50-ish deg.

Side Note: I am still running the origin factory tires with 32,000 miles on them now. Will get new ones installed next week at Discount Tire, just in time for winter.

Can you tell us if you are running your heater and what cabin temperature you set? I assume much of the loss of efficiency at lower air temp is due to cabin heat?

 

[Budman]

Can you tell us if you are running your heater and what cabin temperature you set? I assume much of the loss of efficiency at lower air temp is due to cabin heat?

Hi Martyr

Has been asked previously in this thread, pasting the reply here again. Cheers.



The elevation at home is around 800 ft and at the cabin around 1400 ft. A 600 ft change with most of that coming in the last 30 miles. If I squint really hard at the data I can kinda see a difference in travel direction from the net elevation change but it is subtle.

I keep the cabin temp at 70 to 72 deg. I use the cabin heater freely along with heated seats and stearing wheel. I don't do anything special to try and increase range, just drive and be comfortable.

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