Cold weather range and battery temperature

[jimk]

Hi all,

This is my first winter with my R1T and I've been a bit surprised by the extent to which range has been suffering (and by how slowly the battery seems to warm up) in in recent weeks. I'm in Vermont.

Decided to collect a bit of data on a route I often drive this morning and would be interested to hear if folks think this is all normal, or if this is an issue that requires service.

Departed at 8AM today headed from my home to Stratton Ski Resort, which is 33.5 miles away (all on 2-lane state highways), with a net elevation gain of approx 1400 feet. Car was charged to 95% but not plugged in when I departed and the outside temp was 16F. At departure, my battery temp was 27F and motors were all 32F.

At 8:15, fifteen minutes into my drive, outside temp was still 16F, battery temp was 32F and motor temps ranged from 224-253F.

At 8:30, thirty minutes into my drive, outside temp had climbed to 18F, battery was up to 49F and motor temps were 267-280F.

At 8:48, on arrival at Stratton, outside temp was 21F, battery was 59F and motor temps had dropped to 129-140F. The car reported 72% range remaining, so I used approximately a quarter of my car's range to drive 33 miles.

Does this sound within reasonable expecations to you folks? My other car is an I Pace which, while having a baseline range of quite a bit less than the R1T, doesn't seem to lose quite so much range in cold weather.

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[NY_Rob]

Sounds about right... it takes a lot of energy to bring that huge 135kWh battery pack up to nominal temps.

Look at those motor temps.. 280F trying to heat up the battery.. that takes ridiculous amounts of energy!

EDIT: sorry if I presumed you knew Rivian uses it's motors to run in a inefficient manner to create heat which is used to warm the main battery pack in low temp situations. Tesla started that trend and Rivian copied it.

 

[Mfurman]

Could be the elevation gain plus the cold plus travel speed. What was it on the way back? To go 33 miles on 23% of battery sounds pretty bad. That would equate to about 145 miles on a full charge, which is really bad 145/315 - 46%.

Point of reference 1. In the winter (temps below 32) I do a trip of 200 miles round trip. In the cold weather my Tesla Model Y would start at 315 miles and I'd get home with 30 miles left on the display so lets if we adjust it the math would be 200/275=72.7%. My R1T would do the same commute starting with 315 and I'd get back with 70 miles left 200/240 = 81.6%. Now this is a flat commute and either way it is round trip. In the summer - I'd get back with over 100 miles left 200/215-93%-95%

Point of reference 2 - Winter Commute from LI to Sullivan county - trip is 105 miles, with lots of elevation gain and also high speed driving. I leave with 85% charge approx 265 miles and I get there it is at 35% 90-110 miles left - 105/155 = 68%

 

[Mfurman]

I think I read that the next update is going to allow for preconditioning of the battery and temps while plugged in for planned trips (Tesla already does this). That should help you out quite a bit.

 

[COdogman]

Sounds pretty normal to me... Cold temps, uphill route. If you have a charger that you could leave it plugged into overnight I would do that.

 

[HimuraMOdo]

Randomly picked a town roughly matching your detail here from ABRP shows driving ~33mile with an elevation gain of ~1400ft uses about 16% of the battery. That means your case shows heating up the cabin and the battery used about 7%.
Using 16lbs per kwh for battery and thermal capacity of 950 J/kg*K for a temperature rise of about 32F (20C) ideally would use about 4% of the battery capacity. I'd say your usage was about right.
As for this performance is different than your I-Pace, I'd say it's a different design choice. Rivian can definitely reduce the battery preconditioning but probably at a trade off for battery degradation.

 

[jimk]

Randomly picked a town roughly matching your detail here from ABRP shows driving ~33mile with an elevation gain of ~1400ft uses about 16% of the battery. That means your case shows heating up the cabin and the battery used about 7%.

Your ABRP calculation wouldn't take into account the cold weather, right?

 

[jimk]

Sounds pretty normal to me... Cold temps, uphill route. If you have a charger that you could leave it plugged into overnight I would do that.

Yes, I started cold this morning really for diagnostic purposes. I'm going to put it on the charger overnight and see how it does on the same trip tomorrow (although the weather won't be quite as cold). I can post a comparison here if people are interested.

 

[jimk]

Could be the elevation gain plus the cold plus travel speed. What was it on the way back? To go 33 miles on 23% of battery sounds pretty bad. That would equate to about 145 miles on a full charge, which is really bad 145/315 - 46%.

I arrived back home with 64% charge, so the same 33 miles with a net-downhill and slightly warmer temps used 9% of the battery.

 

[HimuraMOdo]

Your ABRP calculation wouldn't take into account the cold weather, right?

No, I don't think so. Maybe someone can correct me if I'm wrong.

 

[Mfurman]

So quick math is 30% of battery to go 66 miles which is 66/95=69.5% which isn't as horrible.

 

[HimuraMOdo]

I arrived back home with 64% charge, so the same 33 miles with a net-downhill and slightly warmer temps used 9% of the battery.

Do you remember the battery temp right before the downhill drive?

 

[jimk]

Do you remember the battery temp right before the downhill drive?

I want to say it was 53F or something close to that.

 

[jimk]

Does anybody know what the optimal battery temp range is? I had been told at one point by a Rivian Tech that it was 70-90F, but it seemed like this morning like my motor temps dropped back from the high 200s to the low 100s once once the battery hit the 50F range.

 

[NMflyfish]

Related question - will plugging into 120V outlet help with battery temperature? Heading to northern NM next week with lows forecasted in the single digits and no access to a garage. Thanks in advance

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