Poor efficiency on R1S?

[RexRemus]

So having just taken ownership a bit earlier this month, I'm a little worried about the efficiency I'm seeing vs the numbers other seem to throw out here pretty regularly. But specifically, this is "around town" driving that I'm more concerned about, I have the 22s so I know things will be slightly lower, but I figured that would be a bigger issue at highway speeds not 30-40mph stop and go (lots of regen opportunity).

So I'm seeing a lot of 1.7-1.8kWh/mi - or even lower at times. Rarely am I at 2.0 or more. In fact almost never aside from a few downhill stretches on a recent short road trip.

Part of me has a suspicion that some of this is just due to rides being pretty short and perhaps climate control sapping range (running hard at the start, and then being able to taper off once the cabin is at temp). So maybe I'm just always seeing the "worst" case because I'm not driving long enough for things to normalize.

But it's not that hot here now and I'm coming out of a garage with cabin temps of 78-82 at worst the last few days... so I feel like any workload put on HVAC is minimal (cabin temps set to 73-74, and cooling seats off).

I'm also not driving aggressively at all. No room for that on busy Chicago streets anyway, just driving normally, easy start/stop.is this normal? 1.6-1.7kWh/mi seems more off than I'd expect - again maybe not at highway speeds vs the 21s, but specifically at lower speeds with far more regen - which I assumed would be the sweet spot for an EV.

Thoughts? Thanks!

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[TXR1S]

I have an R1S on 22s and see very similar efficiency to yours. 1.7-1.8. Average trip is probably 20 minutes.

I have an R1T on 20s that averages 2.1-2.2. Average trip is 45 minutes.

I think the short trip effect is huge on efficiency.

 

[RexRemus]

I have an R1S on 22s and see very similar efficiency to yours. 1.7-1.8. Average trip is probably 20 minutes.

I have an R1T on 20s that averages 2.1-2.2. Average trip is 45 minutes.

I think the short trip effect is huge on efficiency.

Ok, yeah, I was thinking it might just be that but wanted to verify

 

[electrictaco]

When I had an IONIQ 5, I saw huge impacts on efficiency from short trips that included the startup of motors and the conditioning that goes into the battery upon startup. I bet the Rivian is similar. Most of my driving in my R1S is a longer ~50 mile commute to and from work. On the 21s I see efficiency of 2.1 - 2.4 mi/kWh depending on how fast I'm driving (85 mph - 70 mph respectively).

 

[Redmond Chad]

I agree with the others...based on my experience with other EVs and with my R1S (around 1.7 on short around-town trips, but I saw 2.5 on a freeway trip) that short trips really hurt efficiency because of the start-up costs.

Once you are going, as you've no doubt heard, speed matters a lot - faster speeds make for lower efficiency. When on a long trip and concerned about range, speed is often the top factor.

However, note that in a very heavy vehicle maintaining a steady speed matters a lot too. If you cruise along a lakeside boulevard at 30mph, you are going to do much better than if you drive through town and have to start and stop at dozens of stoplights - even if your average speed is also 30mph.

Around-town trips often have both problems - startup costs on a short trip, AND a lot of starting and stopping. Efficiency can be very poor around town even without high speeds.

 

[RexRemus]

I agree with the others...based on my experience with other EVs and with my R1S (around 1.7 on short around-town trips, but I saw 2.5 on a freeway trip) that short trips really hurt efficiency because of the start-up costs.

Once you are going, as you've no doubt heard, speed matters a lot - faster speeds make for lower efficiency. When on a long trip and concerned about range, speed is often the top factor.

However, note that in a very heavy vehicle maintaining a steady speed matters a lot too. If you cruise along a lakeside boulevard at 30mph, you are going to do much better than if you drive through town and have to start and stop at dozens of stoplights - even if your average speed is also 30mph.

Around-town trips often have both problems - startup costs on a short trip, AND a lot of starting and stopping. Efficiency can be very poor around town even without high speeds.

Honestly this feels a little counterintuitive to me in the sense that if you were doing stop and go (after the "warmup period") that it would actually be beneficial - due to the added regen vs just holding a set speed for the same amount of time. But I guess in practice it's not that simple...

I really did believe that short, stop and go, was the bread and butter for an EV - where it's absolutely worst case for ICE. I guess it's just "better" relatively, but it's also a challenge for EVs

 

[Redmond Chad]

Regen is indeed "better" in the sense that it's better to recover some energy rather than use it all to heat up your brake pads. If you have to slow down (the key phrase), regen is way better than braking. Around-town efficiency would be even worse if we didn't have regen.

But you're still always losing energy when you do it. It's better to maintain a steady speed if you can. Regen doesn't improve your energy use; it just reduces the amount of energy you lose when you slow down. You'll still have to put more energy in to speeding up again than you got from regen while slowing down.

So I agree that regen is "better" relatively.

 

[RexRemus]

Regen is indeed "better" in the sense that it's better to recover some energy rather than use it all to heat up your brake pads. If you have to slow down (the key phrase), regen is way better than braking. Around-town efficiency would be even worse if we didn't have regen.

But you're still always losing energy when you do it. It's better to maintain a steady speed if you can. Regen doesn't improve your energy use; it just reduces the amount of energy you lose when you slow down. You'll still have to put more energy in to speeding up again than you got from regen while slowing down.

So I agree that regen is "better" relatively.

Makes sense I suppose from the sense of a metric based around "distance" - regen-ing to a stop, means 0 distance traveled for however much time you're stopped, but you're still running the core systems... a vehicle holding at 30mph while using "more" energy, is actually covering ground for all that time - you're getting more distance per electron. The regen gains don't outweigh being in motion at that point. I think I just expected it to be much better than it is in reality - first EV, so learning as I go

 

[SANZC02]

Makes sense I suppose from the sense of a metric based around "distance" - regen-ing to a stop, means 0 distance traveled for however much time you're stopped, but you're still running the core systems... a vehicle holding at 30mph while using "more" energy, is actually covering ground for all that time - you're getting more distance per electron. The regen gains don't outweigh being in motion at that point. I think I just expected it to be much better than it is in reality - first EV, so learning as I go

It is also the load to get the vehicle moving. Thank of pulling a wagon or pushing a car in a parking lot. Takes way more energy to get it moving than to keep it moving.

 

[Atlrivian]

I'll add my perspective of someone who has a R1T on 20s and R1S on 22s as well:

For the past year my T gets 2.1-2.3 when I drive my kids to and from school. S is ALWAYS worse. More like 1.8-2 for the roundtrip.

Both cars parked outside. Same stop and go shortish trip. Same average load. I drive the same way (I think). Same drive settings and vehicle height. Makes no sense to me.

 

[TXR1S]

What are the “startup costs” that hurt on short trips? Warming up the battery? Cooling down the battery?

 

[andisimose]

fwiw if I don’t shut off the hvac, wait 30 seconds, turn it back on At the beginning of every trip no matter the outside temp I’m in the 1.6-1.7 range. If I do the power cycle I quickly come back Above 2. That’s on 22s in NC over the last few months

 

[Zoidz]

Honestly this feels a little counterintuitive to me in the sense that if you were doing stop and go (after the "warmup period") that it would actually be beneficial - due to the added regen vs just holding a set speed for the same amount of time. But I guess in practice it's not that simple...

I really did believe that short, stop and go, was the bread and butter for an EV - where it's absolutely worst case for ICE. I guess it's just "better" relatively, but it's also a challenge for EVs

Newton's 1st Law explains it - "An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force."

Even with regen, it takes more energy (unbalance force) to stop and go (say 0-35) than to stay at constant speed of 35.

 

[rpmtexas]

So having just taken ownership a bit earlier this month, I'm a little worried about the efficiency I'm seeing vs the numbers other seem to throw out here pretty regularly. But specifically, this is "around town" driving that I'm more concerned about, I have the 22s so I know things will be slightly lower, but I figured that would be a bigger issue at highway speeds not 30-40mph stop and go (lots of regen opportunity).

So I'm seeing a lot of 1.7-1.8kWh/mi - or even lower at times. Rarely am I at 2.0 or more. In fact almost never aside from a few downhill stretches on a recent short road trip.

Part of me has a suspicion that some of this is just due to rides being pretty short and perhaps climate control sapping range (running hard at the start, and then being able to taper off once the cabin is at temp). So maybe I'm just always seeing the "worst" case because I'm not driving long enough for things to normalize.

But it's not that hot here now and I'm coming out of a garage with cabin temps of 78-82 at worst the last few days... so I feel like any workload put on HVAC is minimal (cabin temps set to 73-74, and cooling seats off).

I'm also not driving aggressively at all. No room for that on busy Chicago streets anyway, just driving normally, easy start/stop.is this normal? 1.6-1.7kWh/mi seems more off than I'd expect - again maybe not at highway speeds vs the 21s, but specifically at lower speeds with far more regen - which I assumed would be the sweet spot for an EV.

Thoughts? Thanks!

I’m having the exact same experience on efficiency. I included it in my service ticket with the 8 other problems I have experienced in the first two weeks of ownership.

 

[rpmtexas]

fwiw if I don’t shut off the hvac, wait 30 seconds, turn it back on At the beginning of every trip no matter the outside temp I’m in the 1.6-1.7 range. If I do the power cycle I quickly come back Above 2. That’s on 22s in NC over the last few months

What exactly is this procedure supposed to accomplish?

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