Enduro Battery Heating

[R.I.P.]

Since getting the Gage Page, drivers have reported the understandable and normal behavior of of the vehicle running its motors in a lossy mode to create heat for the battery. Many have reported relatively high temps in the motors to accomplish this. This is a proven practice (taken from Tesla) that i am glad Rivian is using.

Interestingly, I am not seeing this behavior in the Enduro-equipped R1's. I am back in the PNW for the holidays, seeing below freezing temps but no elevated motor temps to help the battery.

Is this what other Enduro drivers are seeing as well (interested in the colder areas)? I am wondering if the Enduro machine is doing this differently.

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[godfodder0901]

Since getting the Gage Page, drivers have reported the understandable and normal behavior of of the vehicle running its motors in a lossy mode to create heat for the battery. Many have reported relatively high temps in the motors to accomplish this. This is a proven practice (taken from Tesla) that i am glad Rivian is using.

Interestingly, I am not seeing this behavior in the Enduro-equipped R1's. I am back in the PNW for the holidays, seeing below freezing temps but no elevated motor temps to help the battery.

Is this what other Enduro drivers are seeing as well (interested in the colder areas)? I am wondering if the Enduro machine is doing this differently.

How cold is the battery? I'm also in the PNW and have only seen as low as 51F for the battery, and have never seen the increased (Quad)motor temps. Based on others' reports, it seems that the threshold is below 50F?

 

[COdogman]

It seems like battery temp and whether it is kept plugged in have the most to do with this, at least in the Bosch motors.

 

[R.I.P.]

I have

How cold is the battery? I'm also in the PNW and have only seen as low as 51F for the battery, and have never seen the increased (Quad)motor temps. Based on others' reports, it seems that the threshold is below 50F?

I have seen the battery as cold as 39 degrees when starting out. 50 degrees is a an industry standard "floor" for battery temps, and I see the temps get back up over 50 pretty quickly, but w/o any noticeable motor temp spike.

 

[SoCal Rob]

Since getting the Gage Page, drivers have reported the understandable and normal behavior of of the vehicle running its motors in a lossy mode to create heat for the battery. Many have reported relatively high temps in the motors to accomplish this. This is a proven practice (taken from Tesla) that i am glad Rivian is using.

Interestingly, I am not seeing this behavior in the Enduro-equipped R1's. I am back in the PNW for the holidays, seeing below freezing temps but no elevated motor temps to help the battery.

Is this what other Enduro drivers are seeing as well (interested in the colder areas)? I am wondering if the Enduro machine is doing this differently.

Is it safe to assume that the battery temps indicate that heating is occurring even when the vehicle is truly cold and unplugged? If so, are you seeing any kind of efficiency hit? If the battery is being heated and you are seeing a reduction in efficiency then it could be that Rivian is masking the effect by reporting lower motor temperatures when using them to heat the batteries to prevent service calls from concerned owners. If that’s the case, it may be that only DM see this given the later release of the gauge view after Rivian saw an unintended consequence from QM owners. Let’s see if they will do something similar to QM gauges in a future release.

 

[R.I.P.]

Is it safe to assume that the battery temps indicate that heating is occurring even when the vehicle is truly cold and unplugged? If so, are you seeing any kind of efficiency hit? If the battery is being heated and you are seeing a reduction in efficiency then it could be that Rivian is masking the effect by reporting lower motor temperatures when using them to heat the batteries to prevent service calls from concerned owners. If that’s the case, it may be that only DM see this given the later release of the gauge view after Rivian saw an unintended consequence from QM owners. Let’s see if they will do something similar to QM gauges in a future release.

Lying gages is a long-standing practice with automakers, most famously Ford. I hope Rivian does not do this. With the Fords, you can tell because you can push the drivetrain, know intuitively that you are putting heat into it and watch the needle stay in the center; because Ford just wanted to use the visual effect of a gage while in reality is was wired like an idiot light. The gage would really only move if it got too hot.

Unhelpful.

I do not believe this is what Rivian is doing. I can watch the heat come into the motors and watch the efficiency level out when they get up to operating temperature. I see no tell-tails that the gages are lying.

Sure interested in what other enduro drivers are seeing... need more data points.

 

[SoCal Rob]

…Ford just wanted to use the visual effect of a gage while in reality is was wired like an idiot light. The gage would really only move if it got too hot.

Unhelpful.

I’ve owned a Ford, Mazda, and Land Rovers which all used gauges as mechanical idiot lights with 3 states: off, normal, and high. As far as I know they were mechanically damped to give the impression of a reasonable rate of change from one state to another. I’d much rather have an idiot light than that kind of nonsense because it is much easier to see a problem quickly. I seem to recall one of the Land Rovers high-temperature reading being referred to as “replace engine” because by the time the gauge would creep up it was usually too late to avoid a head gasket issue at a bare minimum. The very first new car I bought in 1991 had real gauges (as far as I know) but also had a red idiot light labeled “Check Gages” which illuminated if anything was out of spec. It would ding when that lit up, too.

Sorry, back to Rivian, while I wouldn’t be surprised if they did, I also hope they don’t report fictional values. I think they shouldn’t show orange/red warning colors when motors are intentionally heated to warm up the battery. They could even include a persistent overlay for the temperature gauges stating something like “Motors heating for battery health” or similar. My Ford Fusion Energi (PHEV) would pop up a message if the engine was forced on when you selected EV only and didn’t want or expect it.

 

[wski441]

With absolutely no knowledge of how the coolant is piped between DM and QM outside of the Munro videos. I would think the different coolant and implementation the DM units stay cooler even when running lossy..... so much for armchair engineering ?

 

[R.I.P.]

With absolutely no knowledge of how the coolant is piped between DM and QM outside of the Munro videos. I would think the different coolant and implementation the DM units stay cooler even when running lossy..... so much for armchair engineering ?

Actually... that is my leading theory as well.

As Sandy points out, the cooling design on the Bosch motors is pretty lousy. It is a jacketed cooler that does little to wick heat from the center of the motor, where most of the heat is created. Since the heat-wicking is so inefficient, it takes heating the motor up pretty hot to get much heat "out".

On the other hand, Rivian copied GM with the "hairpins" and Tesla with the oil-bath cooling in the Enduro (kudos Rivian). This is a highly efficient way to cool the motor, so maybe they are getting similar heat out and to the battery with much lower motor temps...?

It is my operating theory until we have more data points... so yeah, you are not the only one thinking that.

 

[KootenayEV]

I don't think it is a hard floor on battery temp where it starts to heat using the motors; I've seen my pack as low as 2C without it engaging the motors to preheat, but I've also seen it kick in preheat as high as 10C. I haven't figured out rhyme or reason for this yet.

 

[R.I.P.]

I don't think it is a hard floor on battery temp where it starts to heat using the motors; I've seen my pack as low as 2C without it engaging the motors to preheat, but I've also seen it kick in preheat as high as 10C. I haven't figured out rhyme or reason for this yet.

"Hard floor" as an industry standard is freezing (32F), with 40 being the lowest recommended temp for charge/discharge activity. 90 degrees-ish is the sweet spot for most chemistries for best performance.

The R1's BMS seems content with the battery 50F><120F-ish. When I start out with the batt temp lower than that, it seems to work to move it to over 50 degrees within a few miles. This is very safely within industry standards (which is what one would expect of course).

 

[KootenayEV]

"Hard floor" as an industry standard is freezing (32F), with 40 being the lowest recommended temp for charge/discharge activity. 90 degrees-ish is the sweet spot for most chemistries for best performance.

The R1's BMS seems content with the battery 50F><120F-ish. When I start out with the batt temp lower than that, it seems to work to move it to over 50 degrees within a few miles. This is very safely within industry standards (which is what one would expect of course).

I've seen my battery several times in the last few weeks below 50F (but above 35F) and the R1 hasn't conditioned the battery, but other times it has, so I'm saying that there seems to be other factors that Rivian programmed into the vehicle that determines when it will condition the battery.

I also am not aware of an industry standard - I'm guess it is somewhat chemistry dependent and also a choice by the manufacturer. Example:

• My 2014 Leaf had a battery heater, but it didn't turn on until -4F and turned off at 10F! I experienced less regen in freezing conditions, but it wasn't zero either.
• My 2018 Model 3 displays the snowflake symbol more often than my R1T in similar conditions over the last month (average ambient below 50F); it also limits regen more. But, when I plug into an L2 charger, it will start putting energy into the pack almost immediately, though concurrently it will run the motor at stall condition (similar to what Rivian does) to heat the pack up in freezing conditions. Repeated acceleration/deceleration (yo'yo ing 10-20mph) will cause the snowflake to disappear sooner (I've only done this a few times as I'm sure it looks foolish and on anything other than empty roads is hazardous!)
• My 2023 R1T seems inconsistent at the battery temps at which it will display the snowflake symbol. Showing the symbol is also not correlated to when the vehicle decides to use the motors to heat up the battery. I also generally have regen available for my first hill of the day leaving my house (-250 ft). My guess from observation is that having a lower SOC seems to influence when the conditioning turns on (as well as battery temp). However, when I plug into an L2 with the battery temp below 50F, as far as I have observed so far, it WILL reliably condition the battery (the noise in the motors is audible, and if I sit in the truck and watch the display, I see the motor temp ramp up). Unfortunately they have the battery temp indicator turn off (or rather to the lightning bolt) when charging, so you can't see what's going on exactly; one time I unplugged as soon as I saw the motor temps start to drop, and sure enough the battery was just over 50F.

I'm not concerned with how Rivian is choosing to manage the battery, but I do find the differences between manufacturers interesting. Cheers.

 

[av8or]

I notice the rise in motor temperature most when preconditioning for fast charging. Have you noticed it when heading to a fast charger?

 

[R1Tom]

Actually... that is my leading theory as well.

As Sandy points out, the cooling design on the Bosch motors is pretty lousy. It is a jacketed cooler that does little to wick heat from the center of the motor, where most of the heat is created. Since the heat-wicking is so inefficient, it takes heating the motor up pretty hot to get much heat "out".

On the other hand, Rivian copied GM with the "hairpins" and Tesla with the oil-bath cooling in the Enduro (kudos Rivian). This is a highly efficient way to cool the motor, so maybe they are getting similar heat out and to the battery with much lower motor temps...?

It is my operating theory until we have more data points... so yeah, you are not the only one thinking that.

But if the coolant temp isn't raised high enough on way to battery, the delta T at the battery is low, and then it takes alot longer to heat up that mass.

My guess is this all comes down to sensor placement. Duals being further thermodynamically from the windings and quads being closer to the windings.

 

[MountainBikeDude]

A quick way to test the motor temp theories would be to cold soak the vehicle overnight, then upon entering the vehicle, set the navigation to a DCFC around 8-10km away. You should notice the motor temps start to go from around 9 or 10c up to around 65-90c within a few minutes, then plugging in at the DCFC, if not fully up to temp, they'll run up beyond around 135c until the battery gets up to around 12c, then drop to around 30c

That's really the only way I can think of to push the system to mimic what's happening in the QM variants.

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