Tesla

I think you'll find most SUV purchases aren't for "ski trips". SWMBO just purhased one -- neither of us ski.

Just like most pickups are purchased by folks who rarely *haul* anything in them!

As to tesla SUV... neighbor owns a RAV4 all electric vehicle (discontinued, limited production). He *traded* his "plug in" Prius for it -- which begged the question, "Why?" (all electric has fixed, limited range).

[It's my understanding that Tesla had a hand in its design/manufacture. Note that an all electric RAV4 is scheduled for release RSN -- must be all those folks here in the southern desert who enjoy SKIING!!]

"I drive less than 40 miles a day, EVERY day. So, I can *always* get where I'm going -- and back -- without the gasoline powered engine (in the Prius) ever needing to run. Why should I be lugging and maintaining that if I'm never using it?"

"But, what if you want to drive to Phoenix, one day?"

"I can borrow one of the other cars in the family -- *or* rent a car for a day. How often would *you* want to drive to Phoenix? Often enough to justify purchasing a car *just* because it had that capability??"

I do ski. And we have a family cabin in the mountains, 190 miles horizontal and 6400 feet vertical from here; I doubt that many electrics could make it up there on one charge, especially at 75 MPH; we can do it in three hours on less than one tank of gas. I'd need a lot of rentals to deal with that. And few electrics are 4WD, which I find strange. The Tesla doesn't have serious regen braking, also strange; I think it uses an induction motor. The batteries die when they get cold, another problem.

Gas powered cars work great. If you are content to never drive far from home, and charge regularly, and live in a temperate climate, electric may work for you.

--

John Larkin         Highland Technology, Inc 
lunatic fringe electronics 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

what do you mean by "no serious regen braking"?

yes it uses an induction motor

different cars are optimum for different things, that goes for gas or electric

-Lasse

The Trump candidacy started out as a joke, but now it seems that it has moved forward to the point where it is actually possible that he could be the Republican nominee. I think he is no worse that all the other crazies running on the Republican side. Sure his lies are a bit more obvious than the other candidate's lies but maybe that's a good thing.

The brakes are conventional. And the regen decl is modest, claimed by design but likely really limited by the technology. Induction motors are mediocre generators.

The Tesla must run its induction motors at huge slip ratios to get that monster acceleration. Efficiency must be really, really low when going 0-60 in four seconds or whatever.

The tradeoff is distorted by government subsidies and the - so far - willingness of the car makers to absorb giant losses.

Note that, even with subsidies, most former electrics are out of production. Batteries just don't have the energy density and lifetime to make sense in most situations.

--

John Larkin         Highland Technology, Inc 
lunatic fringe electronics 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

That's comparable to us "going up the mountain", here: we're at ~2500 and it's 9200. But, we don't go to ski; rather, to paint landscapes (well, *I* don't go at all!)

I coerced SWMBO to opt for a V6 in her SUV -- just to make the "climbs" more reliable. OTOH, it's only a 90 minute drive from here (40 miles) -- so hardly 75MPH! :>

I think the batteries "fail to perform" when they get cold; they

*die* when they get HOT! With ambient temperatures at 100F for at least 65 days a year, thats a fair bit of heat to worry about. (The number of *cold* days is probably 5 -- and those are NIGHTS, not DAYS!)

Some people drive motorcycles because they don't need to worry about passengers. Some people drive minivans to cart around their rug rats, pets and "sports equipment". etc. I.e., there is a reason we have many different "vehicular offerings" available to choose from. I suspect UPS would have a hard time delivering (ALL) packages with motorcycles!

Den torsdag den 13. august 2015 kl. 18.50.39 UTC+2 skrev John Larkin:

electric always have conventional brakes in addition to regen it's a both a safety issue and a power issue, you don't want to use electric power to do braking which you would have to at very low speeds

afaiu the regen is highly adjustable

to accelerate you need power, make power you need torque, torque is proportional to slip so obviously

try looking at the instant milage on your Audi going 0-60 at full tilt

-Lasse

Once we get past the Clipper Gap Speed Trap, there's nowhere for cops to pull people over, so things pick up nicely. I've seen the entire pack moving at 85 or even 90 MPH.

OK, the car is only temporarily bricked. Plug in the battery warmer for a few hours (does the Tesla come with a really long extension cord?) or wait until spring, or call a tow truck; then it will be fine.

I doubt there is any point along *our* climb where you could get a vehicle *up* to 90 MPH and stay on the road!

There's a difference between "can't be used" (regardless of time period) and "must be replaced" (for $3-5k). I can easily find an alternative way to get around if my primary means of transportation isn't up to the task (starting a big V8 in -20F Chicago winters you'd understand what "can't be used" means!). If, in *addition*, I have to make a substantial investment to get it to EVER run again, that's a different story!

[The electric vehicle manufacturers unwillingness to give us any sorts of assurances on this point is what led us away from any sort of hybrid. An 8 year/120K warranty doesn't feel particularly reassuring when you only expect to do 4 years worth of driving in that period!)

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Induction motors are not mediocre generators. You simply invert the inverte r control vector - it has the same efficiency as when used as a motor

The torque is produced by the slip. It is correct that the efficiency is ba d at maximum slip, but it will not be operated at that point, since then yo u would be braking a lot harder than the maximum acceleration. It has a acc eleration 0-100km/h in something like 3 seconds, and how often do you break that hard?

Cheers

Klaus

When plowing into the ass-end of the guy STOPPED ahead of you?? :>

that's what the mechanical brakes are for, they will easily exceed the power of the engine in any car

plus the motor is on the rear wheels, they don't do much work when you really throw the anchor

-Lasse

Not at low speed.

Den torsdag den 13. august 2015 kl. 23.32.58 UTC+2 skrev John Larkin:

not much energy to recover at low speeds anyway

-Lasse

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It seems unlikely that Tesla uses induction motors. Serious electric drives use synchronous motors, then control the hell out of the drive waveforms - we used to call it "micro-stepping" before we had position sensors to let us close the loop.

They won't be the induction motors out of your 1901 test-book.

Evidence?

Or, looking at it another way, the willingness of society to drive technolo gy in a direction which is compatible with minimising green-house gas emiss ions. Not that John Larkin understands what a "green-house gas" is, in any sense other than a political slogan,

But they do make sense for short range commuting, which isn't "most situati ons" but rather the application for which most cars are used, most of the t ime.

John Larkin's self-image is of driving off to the ski-slopes all the time . .. He represses the boring bits which actually represent most of the mileag e he does.

--
Bill Sloman, Sydney

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ter control vector - it has the same efficiency as when used as a motor

bad at maximum slip, but it will not be operated at that point, since then you would be braking a lot harder than the maximum acceleration. It has a a cceleration 0-100km/h in something like 3 seconds, and how often do you bre ak that hard?

The torque is produced by current. 1900AD style induction motors got that c urrent by operating at a large slip. Modern synchronous motors have other o ptions. I does help if you can control the frequency of the AC you are gene rating, which is easier now than it was in 1900.

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Bill Sloman, Sydney

I believe on this vehicle there are motors on both axles. At least someone here said that was how they got the high acceleration. They wanted AWD and got the 3 sec 0-100 kph for free.

My only concern with that would be the touch on the gas pedal. I have driven cars with large engines and the accelerator can be touchy. It doesn't take much to get the rear wheels spinning. I would hope the Tesla cars are designed to keep those horses under control if you sneeze.

--

Rick

On Thu, 13 Aug 2015 23:11:34 -0400, rickman Gave us:

Axles? You are joking. It is four wheel independent.

Motor on each wheel.

The 'D' models have all wheel drive but only two motors:

"With two motors, one in the front and one in the rear, Model S digitally and independently controls torque to the front and rear wheels. The result is unparalleled traction control in all conditions."

(the non-D models only have the rear motor)