General interest - when fast charging (RAN), motor temps increase.

[SeaGeo]

Celsius, not freedom units. And yeah I know from Kyle they push into the low 50C range.

Also, further to my earlier post about motors used to heat the batteries. Was just driving downtown Vancouver. Thermals obviously low and regen/motor output limited warning came up due to cold pack 10C. Once it got past 12C, motor thermals dropped. In any case you get a real sense for how much time is required to bring up, and down pack temps because of the batteries size.

Also noticed a 5% thermal disparity between the left front motor and the front right. Could just be the coolant loop, but interesting since the rear motors are dead even.

One user mentioned this may be the reason for a slight pull to one side when driving, but this hasn't been the case for me. Drives straight and true without intervention from me to correct, obviously road crown dependent.

Yeah I meant to type in C, and my Freedom unit muscle memory overcame things.

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[HaveBlue]

I'm guessing the coolant loop connects the motors, battery and charger components. So one might see heat soak from the battery increasing the motor temps as well; under certain conditions. The temp sensors might not actually be the "motors." They might be the speed controllers that regulate the power to the motors. Those will get super hot if current is shorted through them. I can't imagine that Rivian generates heat by dead locking the stators and running current through them. I wonder if cabin heat is generated using the same system, whatever it is.

I'm going upon my years of flying collective pitch electric helicopters. The speed controllers would get hotter than the batteries and brushless motors.

 

[av8or]

I pulled a trailer all day today and the motor temps stayed below 160 except for once while it was preconditioning it went up to over 200 for about 5 minutes and then started to cool as I pulled into the charger. It must be using motor inefficiency to generate heat. It was in the 30s F.

 

[Chrisy]

How battery and motor and other parts connected with coolant lines I would recommend this Munro live video from youtube:

"Ya Basic (But Efficient)! Rivian R1T Thermal System"

 

[electruck]

I've posted this several times over the years since it was originally published but the coolant loops section is still relevant:

Coolant loops

There is a single overall vehicle water-based liquid coolant system with at least two sub-loops and a grill-mounted radiator and fan, according to Richard Farquhar of Rivian.

A first sub-loop runs through and cools components like the motors and motor inverters. A second sub-loop runs through the battery pack.

Computer-controlled valves and replicated water pumps allow these loops to either operate separately or be joined together in order to exchange heat between the components and possibly the radiator.

For instance, although the battery pack has its own dedicated electric heater it can sometimes be effective and more efficient to share heat from the motors and motor inverters with the battery pack in cooler weather.

The battery pack loop also has a “chiller” connection to the air conditioning system to help cool the pack when it gets too hot. There is also apparently a heat exchange path that allows battery pack heat to help warm the vehicle cabin in addition to or instead of electric resistive heating.

 

[R.I.P.]

I pulled a trailer all day today and the motor temps stayed below 160 except for once while it was preconditioning it went up to over 200 for about 5 minutes and then started to cool as I pulled into the charger. It must be using motor inefficiency to generate heat. It was in the 30s F.

Nice... Smart. Tesla has done this since 2020, it is effective.

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