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300 mile range based on 55mph

I am eagerly awaiting my Performance Model S, but last weekend got me thinking. I drove from Los Angeles to Solvange to play golf(244 miles round trip). I thought wow, I am going to make it on a single charge. I am not sure that is true. On the trip, I never once was below 75 MPH. What is the real range when driving under real conditions? To think you can drive 55 on CA highways is crazy and dangerous.

Assuming you aren't getting the Aero wheels, I'd say the 244 would be very close to the full battery range at 75.

Tesla should have more info in the coming weeks. There has been an app shown on sales floors with range @ mph estimates, but I haven't seen it on the teslamotors.com site yet.

The range estimator in the store only goes up to 60mph
Weird, huh?

Engles' great pictures from the Santana Row event show examples of the range estimator going up to 65 if that is helpful:

https://plus.google.com/photos/117433471618932049710/albums/572080445134...

Daxz posted this from the TMC forum:

Max Range (miles)
Speed 40kWh 60kWh 85kWh
55mph 160 230 300
60mph 150 213 283
65mph 136 197 260
70mph 128 182 245
75mph 116 169 225
80mph 109 156 213

Link: http://www.teslamotorsclub.com/showthread.php/8070-Suggested-Supercharge...

Aren't all these numbers based on the car being range charged (charged to 100% capacity)?

In most cases, we would have to subtract 20% from the range unless I am mistaken.

Just noticed that the TMC thread link also shows the 80% ranges.

Double you speed, quadruple your wind resistance. Drag racks up very fast.

A thought: the Aero wheels suggest about a 5% increase in range. I assume that's at 55 MPH, and only because of reduced drag. So that would be more like (approximate calculation based on 5.00%) 4.33% at 65 MPH, and 3.75% at 75MPH.

My conclusion: if I'm running to the end of my range, I'm going to have to slow down. Specifying the Aero wheels will do something, but not much for my decision points. I'll only get them if I like their looks.

Every version I have seen of the aero wheels look horrible to me. I have seen better hubcaps I am afraid... :(

I wonder how much loss is added on with the A/C or Heat on?

@BYT: Have there been any real photos yet of the aero wheels? As far as I understand, all of the photos shown so far including the Design Studio have been Photoshopped as placeholders until the final aero wheels are ready. Don't get me wrong, I still expect them to look worse than the fan wheels, but I don't think we've seen the final result yet.

Actually the ones at the Tesla Stores on display look exactly like those I'm afraid.

A thought: the Aero wheels suggest about a 5% increase in range. I assume that's at 55 MPH, and only because of reduced drag. So that would be more like (approximate calculation based on 5.00%) 4.33% at 65 MPH, and 3.75% at 75MPH. (EdG)

I am pretty sure you've got this one backwards. The aero wheels have no effect on weight or drivetrain or rolling resistance (idealized). They merely affect aerodynamic drag. Aerodynamic drag is the only range determining factor that changes with speed (again, idealized but very close to reality), and as we all know, two-fold speed means four-fold aero drag. Therefore, the effect of an improved Cd value (i.e., "aero wheels") should be greater at higher speeds. Of course, even with those magic wheels, range will decrease at higher speeds -- but the difference between range w/ aero wheels and range w/o aero wheels will grow with speed, not shrink.

Good point. Poor thinking on my part. Still, 5% or 7% is so close to the norm that it probably won't overtly affect most ride decisions. Only once in a rare while would it make any difference.

There are 6 J1772 chargers in Solvang, so charging wouldn't be too much of an issue, especially if you're playing the River Course. If you're playing the main course, you should convince the Alisal Ranch owners that good hoteliers should have EV charging for their guests!

Also, are you really sure that your average speed is 75mph? I'll accept that the highway miles are, but if you're taking CA-154 off at Goleta, aren't speeds along there slower? You could even pop over to CA-1 west of Ventura and enjoy a slightly more leisurely drive.

How is the range determined anyway? Has anyone at Tesla actually driven a fully charge 85kWh battery until it was at the critical recharge level and recorded the actual mileage or is this strictly an unproven estimated mileage based on a math calculation?

Also, is the increased range for the aerodynamic wheels and tires actual or only calculated?

@DallasTXModelS, I have seen and have photo's of Model S Vin #000001 and it has over 20k miles on it so I think we can safely say they are well aware of the real world battery limits. The car did NOT however have aerodynamic wheels on it.

Dallas;
Supposedly, the beta "real-world" users were finding the range estimates were conservative; they were doing up to 15% better.

Brian H;
That's great to hear, considering the unrealistic numbers usually found on ICE window sticker which are usually obtained by professional drivers that coast alot and don't jackrabbit start.

Also, there is the regenerative braking feature that gives back some battery charge during braking. I've always been able to get better than reported mpg due to my driving habits. I very rarely brake though which makes me wonder if I am going to benefit any from the regenerative braking.

I saw in a beta test drive video the driver saying that he doesn't brake very much either because the electric motor slows down the vehicle when letting up on the accelerator pedal. I'm wondering if regenerative braking also happens when the car is slowing without the brake pedal being depressed or does the brake pedal actually have to be depressed to cause the regeneration.

In both the roadster and the Model S, the brake pedal is for brakes, and the regeneration happens when you back off the accelerator. It feels like strong engine braking on a manual transmission ICE, except it goes all the way down to nearly stopped. It's wonderful: one foot driving much of the time.

Regenerative braking is only better than wasting heat the way friction brakes do. It recovers, at best, 50% of the kinetic energy of the vehicle but in most instances it's probably more like 33%. The exact amount depends on the maximum amount regeneration is allowed to give the batteries and the state of charge of the batteries. Not using regeneration and letting the car glide down without regeneration is usually the most efficient because all the kinetic energy--other than tire rolling resistance, wind resistance and bearing losses--is used for forward motion. There is also probably some speed above which it's a wash or negative but for normal urban and suburban driving gliding is much better than regeneration whenever there is a choice.

I can understand why Tesla did put the regeneration on the gas pedal rather than on the brakes: It's far less complex than a system that has regenerative brakes (like the Toyota system). However, in my opinion, the most efficient way is to have no regeneration on the accelerator and all the regeneration on the brakes. That way gliding is automatic rather than requiring foot education to always press at the sweet spot.

@Jerry3:
I can't stand the way that automatics coast - its awful to drive an automatic for that reason. Having driven the roadster around 600km the regen on the throttle is fantastic. You can control the car as well as with a manual transmission, making spirited driving on winding roads a real pleasure.

The Toyota regen on the brake has generated quite a lot of negative response from drivers because you end up with a strange braking response.

With regen on the throttle you can still coast to a stop - you have even greater control than lifting off and applying the brake - it takes about 5 minutes to get used to it.

If the Tesla coasted like an automatic it would totally wreck the driving experience and I would never have been as keen on going EV.

Agree. This is why I always drive the Leaf in eco-mode, more regen on the accelerator pedal. Having it on the brake pedal just makes it difficult to get max regen braking with no mechanical braking.

Also the CC in the Leaf won't use more regen than what you get with no pedal pressure at all. Thus, in steep downhills, the CC is not able to hold the speed and I have to feather the brake. The additional regen on the brake pedal is usually enough, but it's very hard to find the point of max regen/no mechanical braking. It is MUCH easier to find the "coast" point on the accelerator.

So in conclusion, I wish the Leaf had all it's regen on the accelerator pedal and none on the brake pedal like Tesla.

@jkirkebo:

That's a major design problem with the leaf CC - if you touch the brake you should cancel the cruise, so you'd have to reset it again at the bottom of the hill. How annoying!

@jerry3 It recovers, at best, 50% of the kinetic energy of the vehicle but in most instances it's probably more like 33%.

That's not entirely true. Regen is really efficient, you get more like 70% real recovery for strong regen, maybe even more, as long as rate of deceleration doesn't go too high and speed itself doesn't make huge impact on deceleration rate (aero drag and rolling resistances). There are very few losses on the way from wheels to back in battery, engine=90%, PEM=95%, Battery itself=95%. 0.90*0.95*0.95 = 0.81225 ~= 80%.

Of course if you slow down slower than you would with coasting you are actually using energy to produce slight acceleration so that all is just relative. Regen losses themselves are quite small, you get that approx 80% back no matter which rate you are decelerating, but only from the portion of the kinetic energy that would be otherwise lost on braking. You wont get anything back if you match the coasting speed, and losses are always there.

(same 80% from getting into speed and again 80% from regen makes 0.80*0.80 = 0.64: which means you wont ever get more than approx 60% of the energy you used back into pack even if there were no other losses than just drivetrain losses)

I prefer to look at the regen in the accelerator pedal as a safety feature. If I ever loose my brakes, I can still use the regen to slow down. Safety first children :P

+1 for regen on the accelerator pedal.

So what is the best way to slow down to a halt when the light just turned amber? And is it always better to take roads with more traffic lights vs. ones with less with regenerative braking?

By far the best efficiency is to set the cruise control, and neither accelerate nor slow.

And to do it by saying in your own voice, "Set CC to 55 Tessy"

Mark E,

- I can't stand the way that automatics coast - its awful to drive an automatic for that reason. Having driven the roadster around 600km the regen on the throttle is fantastic. You can control the car as well as with a manual transmission, making spirited driving on winding roads a real pleasure.

Yes, I don't like the way an automatic coasts either. Toyota's attempt to simulate one means you have to have an educated foot to get around it. After a lot of practice I can do it pretty consistently, but it would be so much easier if I didn't have to.

As far as the "strange braking behaviour" goes, it's like any other car. You have to get used to each car's idiosyncrasies (Though it was kind of hard to get used to the VW TDI's habit of shorting out the battery every year and requiring a tow). Other than that you can feel the transition from mostly regen to mostly friction braking if you really try hard, there's no other effect.


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