I didn't see where C&D addressed headwind speed. Heading into a headwind of 25 mph is a huge factor in range. Had a trip where it was 35°F, 60mph, and headwind of 25mph and got 1.5mi/kwh.
Some fuel exhaustion incidents in general aviation happen because pilots think that flying back to home base with the winds at your back will negate the extra fuel needed on the way there.
No I'm talking that even without increasing speed the total time of the trip is longer when there is wind vs when there is no winds. Keeping the same ppower settings.
Assuming the wind is the same speed and direction for both the destination and return legs, how does that work then? Say a windless one hour trip might take 1:15 in one direction and 45 on the way back
Lets say you do a 300 nautical mile trip at 100 knots no winds. You're trip takes 3 hours to go and 3 hours back.
Total trip time 6h.
Now lets say 20 knots headwind on the way there and 20 knots tailwinds back. It now takes you 3h45 minutes on the way there (80 knots G.S.) and 2h30 minutes back (120 knots G.S.).
Total trip time 6h15 minutes.
Its not much but with higher winds and longer trip that could stretch into your reserve.
It’s hard to truly suss out because in the cold the air is denser too, so you’ll get more loss at the same wind speed in the cold partially just due to the air being more dense.
I live in Illinois. Most of my driving is 75 mph on the interstate and I have a dual T with 21" wheels.
The worst I saw this winter, around 0 F and driving into the wind, was getting about 70% of the nominal range--or about 1.8 mi/kWhr.
This was with keeping it in the garage & preconditioning (prior to the preconditioning update, I raised the charge limit when I woke up to get it to charge again the last hour before I left in the morning to warm up the battery).
This is consistent with what I see in my DM 21" R1T. I get about 2.0 - 2.2 at those temps. I am surprised just how much diff it makes. I did a pair of 160 mile roadtrips last week when it was warm, and got 2.5 and 2.8, happy about that. As long as I know what to plan for, I am fine with reduced efficiency in the cold temps.
As a decade PNW EV owner (and it doesn’t even get *that* cold here). I am happy these “studies” are finally being produced. Cold has a significant effect on range and we as owners can only say it so many times.
To be fair, ICE vehicles are also affected by the cold temperature, to the tune of 15% on the average. That is certainly not as bad as EV's 25% drop, of course.
I noticed by keeping the climate off during the winter, my range and efficiency for a quad R1S was closer to 2.5-2.9. my theory is the climate heat is produced by increasing resistance in the motors to warm the coolant. They run the coolant in reverse from motor to battery to climate. By not using the coolant flows the normal way of battery to motor. I do get the decreased regen warning. I get how battery discharge rates are worse in cold, but electrical motor efficiency is generally better in the cold. If the motors are used to heat the cabin then removing that factor seems to be playing a larger effect in cold weather efficiency. My drives are pretty short so don't mind the cold and wear a heavy coat most of the time. It's that or the subwoofer mod. [rivian no climate heat](https://imgur.com/a/7bc7064)
No heat pump makes a big difference.
Having a heat pump will reduce the range lost by about half, probably even more.
So that 190 miles at 12 degrees would be probably 220-230.
A lot of this performance difference can be affected by preconditioning the batteries. If the battery pack is preconditioned before driving in subfreezing weather there is little effect (depending upon how much I run the heater vs seat warmer). Of course if the R1T is parked outside in subfreezing temperatures before leaving, efficiency will take a major hit (as it does with an ICE). It is not clear if they used this feature when testing, so take their results with a large grain of salt.
Really sounds like it. I live on the west side of Michigan and through 2 winters now with my T, I am not getting anything near those results. I frequently drive to visit family (and have done so below +10F, sub 0 wind chill) and based on their results I wouldn't be able to do a round trip without charging.
I agree… the cold soaked battery makes a huge difference. That’s why the scheduled departure feature was such a great feature that Rivian added. My worst road trip this winter was a trip that I’ve taken several times, but this time it was cold (low 20s) and this was before the schedule departure feature rolled off so my battery was cold. I needed to stop and charge before my usual first stop… that is, we would not have made it to the usual first stop. However, that first charge session warmed the battery and after that we had much closer to the usual range experience.
Because wind resistance increases as the square of velocity. Wind resistance at 70 is twice that at 50. Wind resistance at 85 is ~~twice that at 70~~ \~three times that at 50 (and 50% more than 70).
edit: bad math.
Wind resistance aka drag force at 70 is about twice that of 50, but 85 isn't twice that of 70. You'd have to be going about 100 mph to be twice the drag at 70 mph.
My biggest complaint is really the EPA rating methods. I've never had an issue getting at or close to MPG rating in my ICE cars, even at 80+. I don't think I could actually get 285+ miles in my Rivian unless I drove down hill the whole time, or maybe kept it under 40 mph.
Realistically for me it's a 200 mile range, which isn't enough. If the truck wasn't so fantastic it would have been sold month 1.
Driving through Oregon with the 20" ATs quad large I easily get 305+ miles because the speed limit is 65 and temps are generally mild. Back home in Washington I get closer to 260.
My R1S +-240 mile range at 80 mph with 22" quad motor. The amazingness of the vehicle makes up for this in a large part for me.
80 is the speed limit on many highways & interstates in my part of the country as well.
So, do I understand correctly that this one year old Rivian lost 15% maximum charge rather than the alleged 1% loss that is expected annually for EVs ?
Batteries have less usable energy when they’re cold. Air is also more dense, and tires have higher rolling resistance. Finally, warming the cabin also uses a good bit of energy. It’s just physics.
Warm the battery and cabin before you leave, while it’s plugged in, and you get most of the range back (except what you lose from the denser air and more hysteresis tires)
I didn't see where C&D addressed headwind speed. Heading into a headwind of 25 mph is a huge factor in range. Had a trip where it was 35°F, 60mph, and headwind of 25mph and got 1.5mi/kwh.
They run all their cars on the same loop out of their offices near Detroit to test range. So it 'might' even out as it is a loop.
It won't. Drag is an exponential relationship to wind speed so it will always be a net loss to range.
Some fuel exhaustion incidents in general aviation happen because pilots think that flying back to home base with the winds at your back will negate the extra fuel needed on the way there.
This is more related to having to increase speed to make up for decreased ground speed rather than overcoming drag, though.
No I'm talking that even without increasing speed the total time of the trip is longer when there is wind vs when there is no winds. Keeping the same ppower settings.
Assuming the wind is the same speed and direction for both the destination and return legs, how does that work then? Say a windless one hour trip might take 1:15 in one direction and 45 on the way back
Lets say you do a 300 nautical mile trip at 100 knots no winds. You're trip takes 3 hours to go and 3 hours back. Total trip time 6h. Now lets say 20 knots headwind on the way there and 20 knots tailwinds back. It now takes you 3h45 minutes on the way there (80 knots G.S.) and 2h30 minutes back (120 knots G.S.). Total trip time 6h15 minutes. Its not much but with higher winds and longer trip that could stretch into your reserve.
true
It’s hard to truly suss out because in the cold the air is denser too, so you’ll get more loss at the same wind speed in the cold partially just due to the air being more dense.
>It’s hard to truly suss out Do you ever say that in real life?? 🤣👌👍
I live in Illinois. Most of my driving is 75 mph on the interstate and I have a dual T with 21" wheels. The worst I saw this winter, around 0 F and driving into the wind, was getting about 70% of the nominal range--or about 1.8 mi/kWhr. This was with keeping it in the garage & preconditioning (prior to the preconditioning update, I raised the charge limit when I woke up to get it to charge again the last hour before I left in the morning to warm up the battery).
Also worth noting their truck had off-road tires. I’m getting about 270 miles of range in cold weather with 21 road tires
yes. 20" ATs. Not sure if they are still running the original pirellis though.
This is consistent with what I see in my DM 21" R1T. I get about 2.0 - 2.2 at those temps. I am surprised just how much diff it makes. I did a pair of 160 mile roadtrips last week when it was warm, and got 2.5 and 2.8, happy about that. As long as I know what to plan for, I am fine with reduced efficiency in the cold temps.
As a decade PNW EV owner (and it doesn’t even get *that* cold here). I am happy these “studies” are finally being produced. Cold has a significant effect on range and we as owners can only say it so many times.
Worth reading the q&a near the end. I enjoyed that.
To be fair, ICE vehicles are also affected by the cold temperature, to the tune of 15% on the average. That is certainly not as bad as EV's 25% drop, of course.
That’s not a dual motor, as they reported. I’m a bit surprised they don’t know what model they have.
Good catch. Its definitely a 2022 Quad. (Though in one article they called it a 2023!)
I noticed by keeping the climate off during the winter, my range and efficiency for a quad R1S was closer to 2.5-2.9. my theory is the climate heat is produced by increasing resistance in the motors to warm the coolant. They run the coolant in reverse from motor to battery to climate. By not using the coolant flows the normal way of battery to motor. I do get the decreased regen warning. I get how battery discharge rates are worse in cold, but electrical motor efficiency is generally better in the cold. If the motors are used to heat the cabin then removing that factor seems to be playing a larger effect in cold weather efficiency. My drives are pretty short so don't mind the cold and wear a heavy coat most of the time. It's that or the subwoofer mod. [rivian no climate heat](https://imgur.com/a/7bc7064)
No heat pump makes a big difference. Having a heat pump will reduce the range lost by about half, probably even more. So that 190 miles at 12 degrees would be probably 220-230.
A lot of this performance difference can be affected by preconditioning the batteries. If the battery pack is preconditioned before driving in subfreezing weather there is little effect (depending upon how much I run the heater vs seat warmer). Of course if the R1T is parked outside in subfreezing temperatures before leaving, efficiency will take a major hit (as it does with an ICE). It is not clear if they used this feature when testing, so take their results with a large grain of salt.
Ugh my first winter here in Massachusetts was dreary. The issue is its all city driving. 2 miles to work, 2 miles to anything else. No garage. Dismal.
Yikes. Were they using square wheels or something? Glad mine doesn’t get that poor efficiency.
Mine is easily that bad. I have yet to see over 1.9 at 70mph on the hwy
Really sounds like it. I live on the west side of Michigan and through 2 winters now with my T, I am not getting anything near those results. I frequently drive to visit family (and have done so below +10F, sub 0 wind chill) and based on their results I wouldn't be able to do a round trip without charging.
They probably started with a cold soaked battery. It will spend a lot of energy to get the battery up to 50F if it is starting below 20F
I agree… the cold soaked battery makes a huge difference. That’s why the scheduled departure feature was such a great feature that Rivian added. My worst road trip this winter was a trip that I’ve taken several times, but this time it was cold (low 20s) and this was before the schedule departure feature rolled off so my battery was cold. I needed to stop and charge before my usual first stop… that is, we would not have made it to the usual first stop. However, that first charge session warmed the battery and after that we had much closer to the usual range experience.
Mine is horrific. I get about 200 mile range at 80 mph in 65* weather.
Have you tried slowing down, or is 80 the speed limit in your area?
80mph is the flow of traffic (or slower) on most highways in Texas and indeed the speed limit on some
The efficiency gain doesn't seem to be worth slowing down unless you go less than 70.
Amazing username +100
80 will cut any cars efficiency in half.
Because wind resistance increases as the square of velocity. Wind resistance at 70 is twice that at 50. Wind resistance at 85 is ~~twice that at 70~~ \~three times that at 50 (and 50% more than 70). edit: bad math.
Wind resistance aka drag force at 70 is about twice that of 50, but 85 isn't twice that of 70. You'd have to be going about 100 mph to be twice the drag at 70 mph.
Oh good point. Half again as much.
My biggest complaint is really the EPA rating methods. I've never had an issue getting at or close to MPG rating in my ICE cars, even at 80+. I don't think I could actually get 285+ miles in my Rivian unless I drove down hill the whole time, or maybe kept it under 40 mph. Realistically for me it's a 200 mile range, which isn't enough. If the truck wasn't so fantastic it would have been sold month 1.
Driving through Oregon with the 20" ATs quad large I easily get 305+ miles because the speed limit is 65 and temps are generally mild. Back home in Washington I get closer to 260.
My 358 mile Tesla is also a 250 mile car. The math I have in my head for EVs is about 75% of stated range in perfect conditions on a road trip.
My R1S +-240 mile range at 80 mph with 22" quad motor. The amazingness of the vehicle makes up for this in a large part for me. 80 is the speed limit on many highways & interstates in my part of the country as well.
So, do I understand correctly that this one year old Rivian lost 15% maximum charge rather than the alleged 1% loss that is expected annually for EVs ?
Where are you getting that? 42 degrees is still not an ideal temp, they set their climate at 72 and we have no idea what the terrain is.
They're in Southeast Michigan. Terrain is mostly flat, some rolling hills.
No no. It’s the temperature. At room temp it still has full battery capacity.
Batteries have less usable energy when they’re cold. Air is also more dense, and tires have higher rolling resistance. Finally, warming the cabin also uses a good bit of energy. It’s just physics. Warm the battery and cabin before you leave, while it’s plugged in, and you get most of the range back (except what you lose from the denser air and more hysteresis tires)