Awesome range when practicing energy management -- range is as advertised or better in my Cybertruck

[Trekboy]

This would be a good thread for Elon to chime into....

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[webspeedracer]

V2


Hear me now and believe me later...

Momentum is not energy and it is not in the equation.
The critical components are:
Potential energy: Height x mass x g
Kinetic energy: 1/2 mv(2)
Drag force : The difference in drag at 50 kph and 100 kph
is 500%

Probably some other factors like rolling friction but who cares....

Ok so you have the physics equations, now do the calculation for two scenarios:
1) round trip energy in the car with accel/regen behavior to maintain constant speed, with heat losses during accel and regeb
2) a fluctuating speed that is lower than constant when ascending, higher than constant speed when descending (coasting without regen). In this scenario, you have losses only due to positive throttle application, but you have zero losses due to zero regen. You can even modify this scenario to match the scenario#1 constant speed on the uphill just to eliminate variables. Even with this modification, Scenario#2 will still be more efficient because no energy lost during regen, conservation of momentum carries the vehicle farther forward than Scenario #1, “for free” (to quote another poster on this thread)

Of course caveats still apply with Scenario#2: comfort with excess speed, care not to annoy/impede drivers around you, etc.

 

[webspeedracer]

Don't worry, I heard GM is working on. Their research program to harvest the hydrogen in the air and use braking energy to convert it to gasoline is running in parallel with their hydrogen vehicle development program. A win in either of these difficult potential fuel sources would vault them ahead of Tesla.

They are calling their program to synthesize gasoline from braking energy ultium braking (tm) and they claim, once developed, it could be applied to their entire lineup and even solar powered EVs will be equipped with gas collection tanks, so they can help fill-up the tanks of ICE vehicles, all powered by clean solar energy!

Mary is still leading the way!

Well played, sir…well played

 

[Cyber1qhorsey]

I've seen in a 'hater' YT video the driver complain about excessive regen braking, on flat city streets, when foot is lifted from the pedal?. I assume that's easily adjustable...in user settings? I do need to download the Owners Manual soon!! In fact, in said sucky video the driver refused to look at the center console once! As if he would never use it!

 

[Aces-Truck]

With Hybrid Prius', Hypermiling has been proven to be amazingly efficient. And that's done exactly as the OP suggests. The only unknown here is if Tesla's Regen is more efficient then Toyotas.

When I first got my Prius, I would use this technique to see how efficient I could be. But after several years of this, I found I just drove it. More enjoyable rides.

 

[SixZo]

Has consensus been found on whether it is more optimal to keep small bit of regen going during downhills vs neutralize it?

My approach has always been to just have the slightest amount of regen going such that I can maintain my desired speed throughout the slope. Maintaining speed seems most efficient to me (albeit this is purely gut feeling/intuition).

 

[HaulingAss]

Has consensus been found on whether it is more optimal to keep small bit of regen going during downhills vs neutralize it?

My approach has always been to just have the slightest amount of regen going such that I can maintain my desired speed throughout the slope. Maintaining speed seems most efficient to me (albeit this is purely gut feeling/intuition).

I already provided the correct answer but I will elaborate:

It depends upon the speed because aero drag increases with the square of your speed. And the exact speed at which the strategy becomes a wash as the speed increases will be different for different cars, different grades (both in length and steepness) different amounts of cargo and passengers and different temperatures and air densities. As the speed rises there is a crossover point on any given grade and vehicle at which it would be better to regen than to continue accelerating. The longer the grade, the slower you should go (to a point, I suspect regen is more efficient at 30 mph than at 7 mph).

If the crossover point on a given grade happens around 50-55 mph in my Model 3, I would expect the Cybertruck to be maybe 5-10 mph slower since it's less aerodynamic. But a short steep downgrade followed by an upgrade would increase the optimum speed one should allow the vehicle to coast up to using gravity. As you near the bottom of a grade, ease off the regen and build a little more speed (momentum) than you had as you descended the long grade. That's particularly important if immediately entering an upgrade (because the upgrade will scrub off speed before the cumulative aero drag adds up to much).

To further complicate matters, the optimum Wh/mile will be achieved at different speeds depending upon whether the cabin heat is working hard or not. If the heater is on, you want to have less minutes of heater use so it's worth it to take a small aero hit and drive slightly faster.

As you can see, there is no simple answer, it depends upon the specifics in every situation. It's an art, which is what might make it fun for some people. In general, maintain your momentum over shorter distances (for example if the road is a series of short steep whoops), but use regen to control your speed over longer downgrades (to minimize the time spent at high speeds where aero drag is high).

A better way to say that is to shoot for maximum efficiency, avoid short bursts of uneccessary regen, just coast through the small stuff, picking up speed but regen down the really long grades to control your speed and minimize long periods of high aero drag.

 

[csphili]

Although I drove 65-70 on freeway and speed limit on streets, energy management is key. For example, on a long down hill I coast by not regenerating nor using any power. If you see the green bar, you are regenerating. Press the power pedal slightly to remove regen. If you see the gray power bar go up, you pressed too far and are now using power. Sometimes going faster downhill will increase range because you stop regen and coast as long as you stay within the speed limit. Of course if speed picks up too much you must lift and start regen. Understanding the energy management is key for long range. I call this the Scott Dixon approach, if you follow Indy Car racing you will understand.

Just like me learning to drive my Prius back in the day. Range is a function of your right foot. Watch the bars on the screen!

 

[HaulingAss]

Just like me learning to drive my Prius back in the day. Range is a function of your right foot. Watch the bars on the screen!

I forgot there were people still worried about range, I thought this was an exercise in maximizing efficiency. Yes, for any given battery, efficiency affects range, but I haven't worried about not having enough range since I started driving a Tesla 6 years ago. Once I figured out how quickly a 15-minute driving break at a Supercharger made range a non-issue. Now I just hypermile for fun, when I feel like it.

Of course, I'm not planning on towing a bathroom, kitchen, bedroom and living room on wheels across a thousand miles of Interstate, like 99% of anti-EV'ers do on a regular basis!

 

[Cirrus SR22]

Please explain why coasting downhill is better that regererating.

Because Coasting is 100% efficient and regen is not. If you coast down a 10 mile downhill grade vs regen Your wh/m average will be less by coasting. You need regen to control speed but if you are going. 55mph with regen and can safety go 65mph by lightly pressing the Accelerator (until the green bar goes away but before the power is engaged) you will get better range by going faster. .

 

[SentinelOne]

Just like me learning to drive my Prius back in the day. Range is a function of your right foot. Watch the bars on the screen!

Can Tesla do a sw update to fix my right foot? Seems to be defective vs. range!

 

[Cirrus SR22]

Can Tesla do a sw update to fix my right foot? Seems to be defective vs. range!

Tesla needs a SW update to include a “Coasting” feature.

 

[agordon117]

Tesla needs a SW update to include a “Coasting” feature.

They will never do that. They used to have no regen and then low regen as options, and they removed them from newer vehicles. They have even removed "roll" from newer 3/Y vehicles. They will not add them back in now. Especially with the new EPA rules for measuring range. Only the worst mode will be used to do their calculation, and not having regen definitely hurts with the way the epa measures range.

 

[Woodrick]

So NOT using "regen" increases efficiency?
Interesting, completely counterintuitive to what my impression was.
Maybe there is a issue with the CT regen that is causing the bad 450+ wh/mile numbers we are seeing with so many other vehicles?

Correct, but don't get enamored in the concept, because braking kill it.
Hypermilers will add just enough acceleration so that they can arrive at the next stop with no braking. But that means that they end up going slow and being obnoxious.

In normal operation, regen accounts for about 30% of the energy that you use. If you are a hypermiler, then coast. If you are most people, use regen.

But the number #1 kill of range is speed.

But honestly, it doesn't matter. Rarely do you use all the range up.

 

[Woodrick]

Afaik I know it won't go into park if you are moving unless you hold park for a few seconds, which would engage parking brake in a emergency if you lose your brakes

It you stop moving, the car will go into "hold" not park.

If you get out of the car it goes into park or if you are sitting for something like 10 minutes, it will go into park.

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