Is this efficiency drop normal?? (First road trip)

[Doctorjorts]

We did our first road trip this weekend with the R1S. (First BEV road trip of any kind!) Drove from Oklahoma City to Fort Worth on Friday night, and back this evening. That’s a 200mi trek which is 3hrs straight through, or 3.5-4 if you have young kids like us. The trip is almost completely level, according to my buddy with a tesla.

On 21s with the aero covers in conserve mode, I was disappointed in our range. On the way there it wasn’t terrible. I did about 2.2mi/kwh and the trip took us 70% of our large pack battery SOC. So on the way back we left with 90% SOC, and we had a direct headwind the whole time, and added 44kwh at a dcfc halfway because we weren’t going to make it home. According to weather.com the wind was 15mph, but at the charge-up the rain was coming down sideways and I bet it was closer to 25. Struggled to get more than 1.8mi/kWh and usually lower than 1.5 unless I was drafting behind a semi. It was a little chilly but never less than 40degF even towards the end tonight, and my tires were a little lower than the recommended 48 because of the cold, but still over 42psi.

So is this huge drop in range expected from a headwind alone?

Also, in the gauge view I could see the front motors nearing overheating in conserve mode, such that the bar turned orange and the diagram of the vehicle turned orange near the front motors, too. Is that expected as well? I never got any warnings on the dash but when we knew we had no range worries I switched over to all-purpose mode.

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[usulio]

How fast were you going?

 

[Doctorjorts]

I usually prefer to hover between 10 and 15 above the speed limit, but when I saw how fast we were burning through the battery I backed off to 70 max and tried to draft.

 

[elektrode]

I’ve recently been getting crappier efficiency. I’ve started to wonder if they changed the meters. It’s not that cold.

My Last 300 miles are at 1.75. My lifetime is 2.11.

 

[cbrcanuck]

We did our first road trip this weekend with the R1S. (First BEV road trip of any kind!) Drove from Oklahoma City to Fort Worth on Friday night, and back this evening. That’s a 200mi trek which is 3hrs straight through, or 3.5-4 if you have young kids like us. The trip is almost completely level, according to my buddy with a tesla.

On 21s with the aero covers in conserve mode, I was disappointed in our range. On the way there it wasn’t terrible. I did about 2.2mi/kwh and the trip took us 70% of our large pack battery SOC. So on the way back we left with 90% SOC, and we had a direct headwind the whole time, and added 44kwh at a dcfc halfway because we weren’t going to make it home. According to weather.com the wind was 15mph, but at the charge-up the rain was coming down sideways and I bet it was closer to 25. Struggled to get more than 1.8mi/kWh and usually lower than 1.5 unless I was drafting behind a semi. It was a little chilly but never less than 40degF even towards the end tonight, and my tires were a little lower than the recommended 48 because of the cold, but still over 42psi.

So is this huge drop in range expected from a headwind alone?

Also, in the gauge view I could see the front motors nearing overheating in conserve mode, such that the bar turned orange and the diagram of the vehicle turned orange near the front motors, too. Is that expected as well? I never got any warnings on the dash but when we knew we had no range worries I switched over to all-purpose mode.

I don't have any numbers, but I've definitely noticed a significant headwind at highway speeds has a noticeable effect on efficiency. Would be the same for ICE, just physics at play.

And I've been noticing a slow drop in the numbers as the temps have dropped. But not as much as I feared, so far... but it's early yet!

 

[SDH]

My very non-scientific opinion, based only on experience, is that the Rivian is more of a brick than you think (cd not great) so head wind is a factor here and over 70mph the efficiency drops off exponentially - not off a cliff but noticeable difference between 60/70/80 mph on range.

 

[goldburger]

I’ve recently been getting crappier efficiency. I’ve started to wonder if they changed the meters. It’s not that cold.

My Last 300 miles are at 1.75. My lifetime is 2.11.

My lifetime on 21's was 2.14. I've been on a loaner on 20's and after 600 miles (yes, the SC hasn't touched my truck yet, LOL) I am getting 2.3 LOLOLOLOLOL

 

[emoore]

So you were going 70-80 and a 15-25 mph headwind. 1.8 miles per kWh sounds like great efficiency.

 

[SANZC02]

I usually prefer to hover between 10 and 15 above the speed limit, but when I saw how fast we were burning through the battery I backed off to 70 max and tried to draft.

Driving 70 into a 25 mph headwind is like driving 95 so if you were doing 1.7-1.8 miles per kW that is actually not too bad.

 

[CrazyOne]

42 PSI is very low. You should be at 50 or 52 while at speed on the freeway. So you were easily 10 psi lower than the ideal tire pressure. Range at 60 or 65 should be much better. Also use recirculate mode in cold weather to limit heat loss.

If you are travelling at 70 mph with 25mph headwind, that is close to driving at 95 mph without headwind. Tire resistance does not increase significantly at higher speeds. As we go faster, the air resistance increases more than linearly.

Having said that, EVs have well known cold weather and highway range issues. Cold weather impact is worse on vehicles with small batteries.

 

[superfly_snook]

I usually prefer to hover between 10 and 15 above the speed limit, but when I saw how fast we were burning through the battery I backed off to 70 max and tried to draft.

so you were doing 80-85 and surprised at the efficiency numbers you got? I am not smart enough to calculate efficiency but I know too well any car gets crap mileage/range at 80mph.

 

[Electrified Outdoors]

The head wind didn't help of course but i think you had three other things going on as well.

Cooler temps reduce efficiency
Lower tire pressure reduces efficiency
Higher speeds reduce efficiency

If the cabin heat was running that will have major impact on efficiency as the R1 does not have a heat pump. Also the truck needs to warm the battery as well.

I have found from driving EVs over the years that the further you get below 50F the more of a range impact you see. It is especially apparent when you get down below 20 F.

Lastly if you get rain or frozen precip expect another hit. You can help things slightly by lowering the ride height into low on the highway.

 

[Olsonsolar]

So you were going 70-80 and a 15-25 mph headwind. 1.8 miles per kWh sounds like great efficiency.

Sounds more like 85-95mph if he likes to run 10-15 over Oklahoma interstates are 75-80

 

[Budman]

I will point you to this thread of mine. It is for my R1T road-trips. Same route taken many times At different temperature. My top speed is 72 on freeway and 60 on state highway. Higher speeds drop efficiency a lot.

https://www.rivianforums.com/forum/...r1t-road-trip-range-vs-temperature-data.8782/

 

[jlstan]

70 is the magic number on these things. I've taken to going back roads and playing with it more. Lots more fun, and get better efficiency anyway.

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