Level 2 Charging in Heated Garage, Battery Preconditioning Not Necessary

[MartinW]

Here is a chat I had with Rivian support. Others who charge in a heated garage with a Level II charger but venture out into cold temperatures, might find it interesting:

Chat started: 8:39 AM, January 25
Thank you for contacting Rivian Service Support and Roadside. This is Mohammad, how can I help you today?

Hello, I have a question regarding the Cold Weather Tips email I received yesterday
In it, it said 'Preconditioning the vehicle before drives, especially in the cold, can help improve performance, range and efficiency.'
I charge at home in a heated garage usually set to about 55 degrees. When I leave my garage it is frequently below 0.
Would I benefit from pre-conditioning given that my garage is heated yet I am headed into cold temperatures?

Hey Martin, fantastic question, and although you're in a better starting position than someone who parks the vehicle outside in these colder temperatures, I would have to assume it would only benefit the vehicles performance to precondition. We haven't really been provided with guidance regarding preconditioning in a heated garage though, so the benefits may not be as significant.​

Preheating via departure time would be another 'thing' I have to do, and would only want to do it if I knew there was a benefit. Is there anyway to get a definitive answer to my question rather than assuming?

I'm trying to gather a better understanding of this for you from some of my colleagues as well if you have a few minutes for me to try and find a definitive answer. I'm also looking through resources to see what I can find to provide you with a better answer than just an assumption.​

Okay, thanks. I'll be here...

Okay Martin, I've gathered some more information. So the reason the email asks to precondition the vehicle is so that the HVAC is not working as hard when you drive to warm up the interior if it's already at temp. When you leave the car without preconditioning, does the HVAC system take a while to heat up? Or is it already relatively warm?​

It is already comfortable. I have not experienced any issues with maintaining a very comfortable cabin temperature, usually 68 degrees, even when the outdoor temperature is -10 or lower.

In that case, preconditioning would not be required since the vehicle already maintains a warmer temperature due to being inside a heated garage. The process of the HVAC system working harder to get to a point where it's warm is what can have a significant impact on range/efficiency.​

So the definitive answer to your question is no, preconditioning in your current scenario is not required. ​

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[cmsjrs]

I would have to respectfully disagree for the following reasons:

The optimal *operating* temperature for Lithium batteries ranges from 68°F to 80°F. Personally, I aim for 75°F to 77°F.

If your garage does not maintain these temperatures, the batteries won't be at their efficiency peak.

Heating large battery packs is time-consuming due to their substantial mass.

Full disclosure: I haven't yet tested the battery temperatures on my wife's new R1S Tri Max, but I plan to soon. However, my recent OBD testing with our other two EVs (Tesla MSP and Hummer EV) shows that without preconditioning, the vehicles struggle to reach optimal battery temperatures while driving in the below-freezing conditions we've had in central Michigan, even starting from a garage at 60°F.

They can maintain these temperatures once achieved, but only if preconditioned in a heated garage while plugged into wall power before departure.

Conversations with some EV engineer friends have confirmed that the battery's target temperature is influenced by various factors, including whether the vehicle is on wall power or not. Preconditioning without wall power isn't as aggressive.

I assume they've balanced the energy used for heating the battery against the potential loss of range, especially if not heading to a DCFC, where a small drop in State of Charge (SOC) isn't as critical.

From my initial tests, preconditioning for 45-60 minutes while connected to wall power has shown a significant efficiency increase of +40% compared to a cold-soaked battery, even in slightly lower ambient temperatures. However, I need to do more testing to confirm these findings.

 

[cmsjrs]

Case in point, this post: https://www.rivianforums.com/forum/...ange-report-part-ii-with-pics-and-data.39222/

He started his day with his battery at 26F. 95 miles later, it had only climbed to 38F. Granted, he did say he made several stops. I'm sure that did not help.

My wife needs to take a decent length road trip tomorrow, 2+ hrs, 140 miles each way. I plan on starting the preconditioning on her truck an hour before she leaves. Hopefully she will be game for my EV nerd experiment, and send me battery temp pics

 

[Taz355]

Case in point, this post: https://www.rivianforums.com/forum/...ange-report-part-ii-with-pics-and-data.39222/

He started his day with his battery at 26F. 95 miles later, it had only climbed to 38F. Granted, he did say he made several stops. I'm sure that did not help.

My wife needs to take a decent length road trip tomorrow, 2+ hrs, 140 miles each way. I plan on starting the preconditioning on her truck an hour before she leaves. Hopefully she will be game for my EV nerd experiment, and send me battery temp pics

I agree with this if traveling further however in my case where I travel 15 min to work and then often 15 min home my battery temps are 60 degrees when leaving and 5 degrees when comming home
and my battery capacity is actually more then next morning than when I got home.
i only charge at work evey 3 to 5 days. Battery stays warmer at work obviously on the days I charge
so I guess you should also take that into consideration

 

[RivAW]

Case in point, this post: https://www.rivianforums.com/forum/...ange-report-part-ii-with-pics-and-data.39222/

He started his day with his battery at 26F. 95 miles later, it had only climbed to 38F. Granted, he did say he made several stops. I'm sure that did not help.

My wife needs to take a decent length road trip tomorrow, 2+ hrs, 140 miles each way. I plan on starting the preconditioning on her truck an hour before she leaves. Hopefully she will be game for my EV nerd experiment, and send me battery temp pics

Unnecessary and a waste of energy. You are not actually “preconditioning”….that is substantially heating the battery to prepare for fast charging and is currently done by setting gps to a dc fast charger location.

It is plenty sufficient to preheat the cabin (while connected to power) for 15-20 mins max. The cabin will be comfortable and the battery is will be warmed. I’ve had single digit temps when I leave in the morning and that 15-20 mins has the cabin at 71, with the steering wheel and seat warmed…and the battery up to mid 50s. Contrast that with parking overnight without charging and my battery temp is low 20s and even after 40 miles of driving at highway speed has only increased to upper 20s

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