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Question on cold weather performance

Kickaha

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Hey there - have a question that I cant find info on and hoping someone has heard something.

I currently own a 2016 Model X (one of the few 60kwh unicorns out here!) and living in the PNW between the hills and the cold weather, battery performance is weak (and that is being kind). In the summer, battery efficiency moves up to just bad.

I know Rivian will have the aluminum cooling plates for the batteries to maintain optimum temp and prevent overheating but does anyone know about Rivian's ability to heat the battery in cold weather to keep it efficient? I know the R1T is being designed for more harsh climates as an adventure vehicle and I have read several articles that talk about battery temp as it related to efficiency but its usually in regard to cooling. I have not read anything that explicitly talks about keeping the battery warm.

I remember an early Tesla article taking about battery preconditioning but I can find no evidence of it in my daily driving.

Just curious if anyone has heard anything?
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EyeOnRivian

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Rivian doesn't do much reporting on their testing let alone the specifics and results from their testing, at least I haven't seen any or others writing about it. However, I have read a few articles where the Rivian EAVs have been driven (tested?) in cold weather climates. For example, back in lat August Rivian took a couple of R1Ts to Tierra del Fuego in Argentina as support vehicles to the Long Way Up documentary. Apparently that's a popular place to test vehicles due to the terrain and cold weather conditions at that time of year. Again, no specific testing results have been made public.

Short of some miraculous test results I doubt we will hear anything from Rivian unless it gets leaked, so I'm personally I'm not holding my breath. I wouldn't be surprised if we have to wait until after Rivian goes production with their EAVs and either individuals or independent organizations do their own testing and make their results public.
 

skyote

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Yeah, no detailed cold weather testing data, but they've definitely done real world testing.

In addition to Argentina winter, they were in Colorado late Jan.

 

ajdelange

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Rivian has done extensive work on battery temperature control. They are smart enough to understand that it is the key to battery longevity which is extremely important. They would not be able to sell the vehicles if they could not warranty the battery for 5 years or more.

Battery temperature is not that critical to performance. The Tesla driver notices two things in cold weather:
1)Regenerative braking is reduced or gone for the firtst 20 minutes or so of a trip.
2)Wh/mi go up.

These are not totally independent of one another but there are other things that are contributors to increased power consumption in cold weather such as use of cabin heat, defrost, seat heater, and steering wheel heater. These seem to be the major consumers. By not generally using any of them except the seat heaters I find my winter consumption is not much greater than summer at 302 Wh/mi vs perhaps 295. But there are other factors too. A really big consumer of energy is anything other than a dry road bed and weather tends to be lousier in the winter than the summer. The air that must be pushed out of the way to let the car through is denser in cold weather than warm. Lubricants are, at least initially, stiffer. I'm not sure about the tires themselves.

On average X drivers seem to operate at about 86% efficiency in summer and at about 94% in summer. If your performance is, as you suggest, much different from that then look to things other than the battery to explain it.

AFAIK the only way to warm the battery in the Tesla is to drive it or charge it. Current flowing into or out of the battery warms it. If you make demands in either department beyond where the BMS thinks temperature needs adjusting the car will heat (via a separate heater in the X and S or with inverter heat in the 3). It seems it would be simple enough to have a feature that keeps the battery in the prescribed range at all times or at programmed times as long as it is connected to shore power. I think the X has something to keep it cool at all times as I occasionally hear the compressor running when the car is in the garage.

Well that's Tesla. Who knows what Rivian will do in this regard.
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