Optimal Battery Temperature for best performance?

[Golfer04]

12 miles to work this morning. Started at 77, ended at 77.

Nope. Was navigating to breakfast. Truck had been in the garage though. Not out in the cold.

Sponsored

 

[Riviot]

My battery never deviated from 69°F today. I think we know the ideal temp now...

 

[Forager]

I’m assuming ideal temp for all gages is at TDC, if it’s not I would like to have a word with Wassym. ?

 

[R.I.P.]

These were my thoughts as well. Was surprised how much of a bias there was for front in AP. Fun having the stats now.

Maybe. Remember that the quad has larger motors in the back, while the enduro has lower gearing in the back... both designs giving a harder "shove" from the back given similar juice (at lower speeds). This means that if the telemetry is showing current (reasonable assumption), then it may use more _current_ going to the front to give similar torque front to rear.

Of course the reasons for front biased regen is obvious (weight transfer under braking).

 

[Donald Stanfield]

Don't get me wrong, I love the new dashboard, but I bet some Rivian PM is watching this thread muttering "I told you so" ? It's just the right amount of information to get us all speculating and second guessing and correlating instead of just trusting the truck.

Everyone was doing that already. You can't throw a stone in this forum without hitting at least three engineers. Being curious and data focused are two traits that make engineers hugely successful. So its not surprising to me what goes on in here.

OTOH I am a people focused person. All this stuff is neat to me but I have no problem outsourcing the figuring stuff out to Rivian.

 

[godfodder0901]

Maybe. Remember that the quad has larger motors in the back, while the enduro has lower gearing in the back... both designs giving a harder "shove" from the back given similar juice (at lower speeds). This means that if the telemetry is showing current (reasonable assumption), then it may use more _current_ going to the front to give similar torque front to rear.

Of course the reasons for front biased regen is obvious (weight transfer under braking).

The motors are identical in the Quad as well. The power difference comes from gearing too.

 

[R.I.P.]

The motors are identical in the Quad as well. The power difference comes from gearing too.

That is how I understood it as well, but there have been some recent reports that the motors are actually larger:

" Quad-motor vehicles fit larger, more powerful motors at the rear with equivalent gearing front and rear. Dual Motor models flip that script with equivalent motors and lopsided gearing: 11.04:1 front, 13.70:1 rear. " (Motortrend, Aug 2023)

I am inclined to agree with you, the motors are the same, the gearing is different... MT may be in error.

 

[godfodder0901]

That is how I understood it as well, but there have been some recent reports that the motors are actually larger:

" Quad-motor vehicles fit larger, more powerful motors at the rear with equivalent gearing front and rear. Dual Motor models flip that script with equivalent motors and lopsided gearing: 11.04:1 front, 13.70:1 rear. " (Motortrend, Aug 2023)

I am inclined to agree with you, the motors are the same, the gearing is different... MT may be in error.

This wouldn't be the first time. The Sandy Munro video with RJ covers this specific question, though.

 

[Dark-Fx]

That is how I understood it as well, but there have been some recent reports that the motors are actually larger:

" Quad-motor vehicles fit larger, more powerful motors at the rear with equivalent gearing front and rear. Dual Motor models flip that script with equivalent motors and lopsided gearing: 11.04:1 front, 13.70:1 rear. " (Motortrend, Aug 2023)

I am inclined to agree with you, the motors are the same, the gearing is different... MT may be in error.

Stator/rotor in the quad is actually larger in the back but they are geared identically. The rear motors are technically capable of higher power but, in practice, they still max out at the same amount. It could be they can tolerate higher current for longer due to the increased size, but we haven't had hard data on how Rivian is doing the control or temperatures until the gauge screen came in to play.

 

[godfodder0901]

Stator/rotor in the quad is actually larger in the back but they are geared identically. The rear motors are technically capable of higher power but, in practice, they still max out at the same amount. It could be they can tolerate higher current for longer due to the increased size, but we haven't had hard data on how Rivian is doing the control or temperatures until the gauge screen came in to play.

This directly contradicts what RJ said when he was asked about the differences in power and torque front to back: "slightly different gearing in the back":

Sandy and Rivian CEO RJ Scaringe talk about the R1T. - YouTube @ 12:34

 

[Dark-Fx]

This directly contradicts what RJ said when he was asked about the differences in power and torque front to back: "slightly different gearing in the back":

Sandy and Rivian CEO RJ Scaringe talk about the R1T. - YouTube @ 12:34

I remember watching this and thinking the same thing, but their EPA certification documentation says they are the same ratio. I've chalked it up to RJ's mind likely being on their future enduro product which was probably still in early engineering validation at the time of this filming.

 

[Rivifan]

Similarly, was surprised at how front-biased the motors are on acceleration and how little regen they attempt to pull from the rear motors.

Flatlander here, FWIW- Ive noticed all four motors mostly equal on acceleration, but will now pay more attention just in case. And I too noticed the front heavy regen, but I chalked that up to physics, figured its just like how front brakes do ~80% of the braking generally.

 

[BrentInCO]

The Rivian fast charger stopped charging my car a little before 80% because the battery temperature was too hot at 130 degrees.

I had driven 4 & 1/2 hours non stop (other than construction delays) in Conserve mode 265 miles, arrived at the charger with 30 miles of range left (10%). This was on October 21, shortly after the software upgrade came available, so I have no basis for comparison on monitoring battery temp, but I’ve done this same drive over 20x without this issue, in much colder and much warmer ambient temperatures. There’s at least 30 minutes of downhill cruising before arriving at this RAN charger. Vehicle had probably been charging for 40 minutes to an hour at this point. I drove away and it’s temperature dropped quickly.

 

[Dark-Fx]

The Rivian fast charger stopped charging my car a little before 80% because the battery temperature was too hot at 130 degrees.

I had driven 4 & 1/2 hours non stop (other than construction delays) in Conserve mode 265 miles, arrived at the charger with 30 miles of range left (10%). This was on October 21, shortly after the software upgrade came available, so I have no basis for comparison on monitoring battery temp, but I’ve done this same drive over 20x without this issue, in much colder and much warmer ambient temperatures.

I take it you didn't get your Rivian home before Midnight and it turned into a pumpkin?

 

[Rivifan]

Flatlander here, FWIW- Ive noticed all four motors mostly equal on acceleration, but will now pay more attention just in case. And I too noticed the front heavy regen, but I chalked that up to physics, figured its just like how front brakes do ~80% of the braking generally.

@zefram47 Sure enough, looked again, and yep my fronts are more engaged on initial acceleration, then they level out. I must not have looked down soon enough, it only takes a couple seconds to get up to the speed limit from a stop

Sponsored