InTheShadows
Active Member
I am by no means an engineer, however to conserve energy I would opt for an electronic clutch that would disengage the wheels from the axle so you do not need to use energy to spin things that are not necessary.
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AWD Test Mule
- Thread starter scaesare
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- Driving Dynamics Model S
I am by no means an engineer, however to conserve energy I would opt for an electronic clutch that would disengage the wheels from the axle so you do not need to use energy to spin things that are not necessary.
JRP3
Hyperactive Member
No. As TEG said the motor is always connected to the wheels, so if wheel speed increases enough it could spin the motor faster than it's max RPM, regardless of the motor being "on" or "off".
Again, no. Different cell chemistry means different C rates, which means power output. Hybrids use cells optimized for higher output rates.
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Not worth the cost, complexity, and added weight. An unpowered electric motor that's just freewheeling would have minimal drag.
JRP3
Hyperactive Member
Note that the ActiveE, using a different kind of electric motor, as this to say about shifting into Neutral:
The funky translation from German uses "electrical machine" instead of "electric motor".
I take this to mean that in the ActiveE, when in Neutral, the controller isn't "off", instead it matches the back EMF from the motor.
Olle
Active Member
What does it matter if motor spins a little faster than max rpm if it is off and just free wheeling? Is there anything in the rotor that gets hurt I thought it was a "dead" piece of metal
JRP3
Hyperactive Member
If they use a permanent magnet motor then the rotor will generate current when spinning, while the AC induction motor that Tesla uses will not unless the controller is powering it.
There are still bearings that have a speed limit, and the rotor itself could overspeed and come apart. I'm not sure which is the limiting factor in the Tesla motor, but there is indeed a limit.
stopcrazypp
Well-Known Member
Most max rpm numbers for motors specify a point where, if exceeded, would result in the motor breaking itself apart (bearing and rotor stability limits).
If there's a permanent magnet (like the ActiveE motor that woof mentioned), it's going to generate a current and might overheat the motor.
Olle
Active Member
A TM investor presentation states that the MS motor is capable of 18000 rpm. At 130 mph I think it spins at about 15500 rpm. But the 18000 probably refers to an electrical limit above which the motor is inefficient. The mechanical limit might be higher.
Newscutter
Member
Yesterday in London, Elon said the MX would be offered ONLY in AWD form. My take on that is if they can't engineer the MX to launch with both RWD/AWD (as on the website) then cost is likely the reason. Therefore, it seems to me the prospect of an AWD MS has become significantly less likely in the near or mid term. If you want/need AWD you'll simply be pointed to the MX. If you don't, then the MS will be your flavor.
I can think of several reasons why:
- They'd have to do a large fraction of the crash testing in both configurations
- Their market research shows that most sales will be the AWD version (pretty much all Northerners will get AWD, and many others will opt for it anyway)
- Fewer configurations makes for easier manufacturing
- Better margins
Nickjhowe
Member
In London Elon also said at 130 mph the battery is doing about 16,000 rpm. He said they could take the car to higher Autobahn speeds but they haven't done the necessary testing to be confident of the motor at 17,000+ rpm.
As to the original post, per @AmpedRealtor it does seem possible that this is Leilani's "special" car.
As to the original post, per @AmpedRealtor it does seem possible that this is Leilani's "special" car.
JRP3
Hyperactive Member
Lets hope Tesla corrects the horrible design flaw and stops batteries from spinning 
Probably Tesla simply wants to keep customers from flip floping as they usually do before chosing among all the S versions and have some simplicity to speed up sales. So buy an S or RWD or X for AWD. They likely will offer both drive versions in both models down the line but don't want buyers to postpone purchases waiting for it. Ups, did I say that out loud?
Probably Tesla simply wants to keep customers from flip floping as they usually do before chosing among all the S versions and have some simplicity to speed up sales. So buy an S or RWD or X for AWD. They likely will offer both drive versions in both models down the line but don't want buyers to postpone purchases waiting for it. Ups, did I say that out loud? 
Johan
Ex got M3 in the divorce, waiting for EU Model Y!
We just got hit with some snow up in PA and I got to REALLY test my 19" Rials with Blizzaks. Night and day compared to last year. I don't know if there was a software change as well, but having the snow tires on made a HUGE difference. The car felt more in control than it did last year.
Close enough to AWD for me.
Close enough to AWD for me.
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