Conserve Misconception

[HyperionMark]

https://www.electronicdesign.com/te...motors-efficiency-and-adjustable-speed-drives

Ok, can you please say what you are trying to get across with that article? I'm not seeing any information relevant to this discussion.

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[lefkonj]

I wish conserve cut power to the rear motor and didn't completely disengage it. I was told several times, don't go from Conserve to any other mode unless you are stopped. I just use all purpose 100% of the time.

 

[Budman]

I agree with the OP. Conserve is fine for tire wear. And, as also noted, conserve only real gets better efficiency at warmer temps based on my data collection from the same 165 mile route driven many times.

 

[HyperionMark]

I agree with the OP. Conserve is fine for tire wear. And, as also noted, conserve only real gets better efficiency at warmer temps based on my data collection from the same 165 mile route driven many times.

Great work! That shows some legit range addition! Good to know much below the 30s you don't get a huge help. Have to do anything with how it heats the motors up to help with other stuff in the vehicle? Or another reason?

 

[Budman]

Great work! That shows some legit range addition! Good to know much below the 30s you don't get a huge help. Have to do anything with how it heats the motors up to help with other stuff in the vehicle? Or another reason?

I think, and I’m only guessing, but it might be because at lower temperatures some energy from the motors goes into keeping the battery warm. If in conserve mode, the two motors have to work harder to provide that energy negating the benefit of shutting off the other two.

 

[greyboundary]

+1 to the original point about chaotic driving. The number of times I see other people towing at 85+ or just doing generally erratic driving is astounding. And my baseline isn’t even granny mode, I do a ton of track days in my ICE car. The bit about trip time not being reduced at a significant consumption/safety cost is definitely under appreciated.

The anecdata on towing in conserve mode is definitely interesting through. I’ve been thinking about how well that works while awaiting my upcoming r1t delivery (next week). I am sort of surprised they don’t lock it out if a trailer is connected. I’m sure the front motor is more than fine to maintain highway speed, but for inclines or acceleration with heavier loads…

 

[Cortles]

Great work! That shows some legit range addition! Good to know much below the 30s you don't get a huge help. Have to do anything with how it heats the motors up to help with other stuff in the vehicle? Or another reason?

I'm such a dork and I love this data too. In my experience, the range estimates on the Rivian have always been "conservative" and when I'm in Conserve mode, that is even "conservative" in how it estimates range - to see that spelled out in the data shared here warms my heart.

Others in this thread have tried to downplay the value of Conserve mode by suggesting that it isn't that great - but in practice, we charge up at home to 100% for a long road trip - we use Conserve on the highway which easily adds 50+ miles onto the 280 mile range. Add to that a more "conservative" drive style (driving 65 on the highway instead of 80)... On a long 6 hr roadtrip, it can be the difference between stopping once for 30 mins charge or having to stop 2+ times for 90+ mins of charging. It all adds up and its all about being smart about how you drive an EV. Net net, an extra hour onto your journey.

Incidentally, I'd really LOVE Rivian to build into the Energy interface some useful visuals/intelligence/calculations based on the above thinking so that we can all be a bit smarter with EVs and long road trips and the decisions we make on speed/mode/etc. Do what you want when driving around town... but for road trips, be more mathematical/scientific about charging/timing ramifications.

 

[RivAW]

My name is Mark and I've *towed* over 1,000 miles in Conserve. Thanks for having me to this meeting of Tires Anonymous.

I want to address a common misconception I see around here sometimes. It seems like people think that driving in Conserve automatically makes it so you have increased tire wear.

On the whole I do strongly believe that Conserve can definitely lend itself to more tire wear, but that is largely only true under two variables:
1. You are driving more aggressively than the average vehicle. This is an extremely heavy vehicle and physics dictate that will increase tire wear.
2. You aren't doing tire rotations enough. This one speaks for itself.

So how do I have pretty normal tire wear driving and towing almost exclusively in Conserve? Well, mainly I just drive conservatively. If I need to do a ton of starts and stops, especially at higher speeds or with the trailer I put it in All Purpose. But on flat long segments of highway I keep it in Conserve. I should get 25-30k miles on this set.

A couple other points:
1. Watch the motor graphics next time you are stopping in AP. You will notice the front motors do a lot of the heavy lifting, especially closer to stopping.
2. Is it possible we as a society drive rather insane sometimes? The normalized driving in most places is way too crazy and barely gets you there any sooner. If you like going fast, I get it, that can be fun sometimes. Just put it in AP and expect increased tire wear even then.

Well, that's the point....Conserve is meant for constant or mostly-constant highway speeds (whether towing or not towing)....

 

[Electrified Outdoors]

Thanks for sharing this.

The difference in conserve I found to be about 5% under ideal conditions. The tires on these vehicles wear very fast, rotating the tires evens out but does not reduce the tire wear.

The concern with conserve mode tire wear comes in stop/go traffic as that can cause abnormal tire wear (cupping/feathering) and traction issues. Not applicable in high speed highway driving.

The front tires will already wear faster due to the trucks being front biased.

One has to determine if the trade-off is worth the slight efficiency gain.

1) Less power available on demand
2) More strain on the front motors and components such as the half shafts (in both torque and regen modes).
3) Less regenerative braking power available
4) Potential for failure of the decouplers (there have been several posts about folks who had them fail and they weren't towing)
5) Of course you don't get the torque vectoring when the rear motors are decoupled but this is mostly for performance driving/handling so not really a thing when towing.

Especially when towing I would be most concerned about #2 and #3.

I get between 1 and 1.2 mi per kwh towing my travel trailer. So best case I have about a 157mi range 100 to 0 when towing. If I could get a 5% boost that gives me an extra 8 miles of range.

With all that said Rivian does have a long warranty on the quad motors and they don't specifically state not to tow in conserve mode. I have had multiple service techs tell me to avoid conserve mode unless its an emergency though they didn't really elaborate on the logic behind the recommendation.

 

[georgethegoat]

It'd be cool if under certain conditions there was a popup on screen suggesting conserve mode.

 

[HyperionMark]

The difference in conserve I found to be about 5% under ideal conditions.

Many, many real world example say this number isn't close to accurate.

 

[Electrified Outdoors]

Many, many real world example say this number isn't close to accurate.

I may give it a try ?

 

[ksurfier]

I may give it a try ?

Just confirmed via real world test:

Concern Mode = gimmick
Course: ~3 miles out, 3 miles back.
45 mph, ~70 F

1st Test - AP
2.51 miles / kWh

2nd Test - CM
2.62 miles / kWh

For this comparison (45 mph), CM is -~4% more efficient than AP, however, motor temps on front were >200 F using CM. In AP fronts were 140 F and rears were 130 F.

Based on a 100% SOC, this could increase range by ~10 miles only.

In order to get a 40 mile increase using CM, there would need to be a 14% difference between AP and CM. For example, 2.55 in CM vs 2.22 in AP.

Likely the last time I’ll be using concern mode
?

 

[Treebeard]

My name is Mark and I've *towed* over 1,000 miles in Conserve. Thanks for having me to this meeting of Tires Anonymous.

I want to address a common misconception I see around here sometimes. It seems like people think that driving in Conserve automatically makes it so you have increased tire wear.

On the whole I do strongly believe that Conserve can definitely lend itself to more tire wear, but that is largely only true under two variables:
1. You are driving more aggressively than the average vehicle. This is an extremely heavy vehicle and physics dictate that will increase tire wear.
2. You aren't doing tire rotations enough. This one speaks for itself.

So how do I have pretty normal tire wear driving and towing almost exclusively in Conserve? Well, mainly I just drive conservatively. If I need to do a ton of starts and stops, especially at higher speeds or with the trailer I put it in All Purpose. But on flat long segments of highway I keep it in Conserve. I should get 25-30k miles on this set.

A couple other points:
1. Watch the motor graphics next time you are stopping in AP. You will notice the front motors do a lot of the heavy lifting, especially closer to stopping.
2. Is it possible we as a society drive rather insane sometimes? The normalized driving in most places is way too crazy and barely gets you there any sooner. If you like going fast, I get it, that can be fun sometimes. Just put it in AP and expect increased tire wear even then.

Drive in conserve mode almost all the time. When I toaster at 5000 miles and check tread depth of the 21” OEM tires I might have 1/64” difference between the front and back. 25,000 miles on the tires and now replacing them. I don’t think this is bad for a high performance tire with no warranty.

 

[HyperionMark]

Just confirmed via real world test:

Concern Mode = gimmick
Course: ~3 miles out, 3 miles back.
45 mph, ~70 F

1st Test - AP
2.51 miles / kWh

2nd Test - CM
2.62 miles / kWh

For this comparison (45 mph), CM is -~4% more efficient than AP, however, motor temps on front were >200 F using CM. In AP fronts were 140 F and rears were 130 F.

Based on a 100% SOC, this could increase range by ~10 miles only.

In order to get a 40 mile increase using CM, there would need to be a 14% difference between AP and CM. For example, 2.55 in CM vs 2.22 in AP.

Likely the last time I’ll be using concern mode
?

Good for you man. You have a vehicle that defies physics. Go back to being the self proclaimed czar of all things tires, even though your advice is always sus.

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