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Prius and Li -ion batteries having been mentioned I might add that : Readied for release in the fall of 2008 the power battery for the 2009 Prius was intended to be of the more advanced Li-ion. However a year earlier there had been a series of fires associated with Sony laptops widely advertised as having Li-ion cells. Since the Prius had no serious competitors at the time ( and IMO still doesn't ) their marketing dept decided why take the risk with these new cells if their adoption was likely to impact sales of their hybrid marque, consequently the MY 2008 car was allowed to carry through September 2008 and become the MY2009. Meanwhile the intended car was partially reverse engineered to enable its use to continue with the existing NiMh battery. Because of the delay the new design car for 2009 MY was eventually released as a 2010 MY in March /April 2009 instead. That car was manufactured continuously from December 2008 all the way through to July 2010. And then for MY 2011 for those ordering leather seats, tan colored seating became an available option. AFAIK that was the only change noted in the MY 2011 brochure as Toyota sought to recover its losses regarding the battery anomaly. Or at least that is my speculation. Going back to the MY 2004 this was the first model year to use the 201Vdc battery with the newly introduced upconverter which allowed the MG1 and MG2 servomotors to run from 500Vdc and gave the Prius an acceptable driving characteristic. Both the earlier versions of previous years using the 273Vdc battery were known to be somewhat anaemic. Incidently both the 273Vdc and 201Vdc batteries were rated at 1.3 Kwh of storage. The conventional lead-acid installed within an ICE vehicle is around 0.9Kwh. The 21Kw upconverter supplied effectively 28Hp from the 201Vdc battery which along with 76Hp from the 1.5L 1NZ-FXE engine supplied a total of 104Hp from 51mph to 99 mph (electronically speed limited). During (regenerative) braking the power fed back into the battery was limited to just 10Kw for battery longevity reasons no doubt. Recently I remarked to a Toyota mechanic that I had seen photographs of Prius brake rotors which seemed lightly used even after 50K miles. He responded that from his end brake corrosion was an issue since there was not enough subsequent friction braking to dry out the rotors from driving in wet weather. For buyers wanting more than the 4 minutes of all-electric driving at speeds below 42mph, the Plug in Prius has been available but there have not been a large number of takers because of price sensitivity to this upgrade. For the same reason GM's Volt sales have not been all they could. Hopefully buyers will move away from this transitional technology and eventually go the full EV route now that public charging infrastructure is more prevalent. First however, manufacturers have to wise up and provide their snow belt customers with well insulated battery enclosures with good thermal management since costwise the battery is the car. My opinion on the future for the Toyota Prius is for the company to realize that the emissions crown is moving over to EVs. Prius is no longer exempt to congestion charges nor allowed HOV privileges in increasing locales. Toyota has to realise that fuel consumption is becoming more the name of the game for hybrids as cash strapped governments move to establish new gas taxes. Smaller engine displacements along with compensatory higher engine speeds will be needed in future for the Prius to attract buyers and this will appear as a more economical route than simply beefing up existing electrical systems. As regards battery chemistry the existing NiMh battery systems are proving good longevity and are unlikely to be swapped out any time soon. Neither do I see an AWD Prius be any more likely to attract buyers than AWD did for the Corolla back in the early nineties. This Hitachi battery may improve the Malibu hybrid but didn't they already take this model off the market once before ?
First just a coupla' nit picks. The phasing graph axis should end with 1440 deg not 1400. And surely the igniter firing order could just as easily be 123..123 etc as be 132..132 ? If you look carefully you can see the sequence 321..321.. which is just a 123 engine being made to run backwards ! Until this article I had never considered the possibility of rolling deactivation before. It seems like a good idea, and before a reader tells me how obvious this is, I might say that pretty much most good ideas are obvious, once someone has taken the time to point them out. So if you are cruising along with rolling de-activation engaged and suddenly need to accelerate then the firing circuits will return to the normal 3-cylinder sequence. In other words, the 480 deg firings revert back to a normal 240 deg sequence. But what is the main advantage here ? Does it allow the crankshaft to run slower in cruise with just three firings per four rotations thus allowing the cylinder loadings to be raised for max effcy ? I would like Ford to take this to a parallel twin model with a total cylinder area equal to that of the three cylinder they are now playing with. That would ensure the same power and by using the exact same stroke would subsequently ensure the same torque. Advantages would be that valve train friction losses would drop by 50%. And then there's the cost factor of the engine being proportional to the number of machined parts. I think it is fair to say that component size is not a cost driver as we are talking of parts made from iron and aluminum here.
Apparently air con units need over 3kw to run, and over 12kw to start them up. Then I would respectfully say that if your air con pulls a 12Kw surge at start up, then it's time to replace it with more modern equipment which doesn't rely on motor control technology from the 1950's.
Davemart, that is what I say too. My story concerns my older fridge that the local utility wanted me to replace. In their promotions, flyers with the bill and a feature in the local newspaper etc, I happened to notice that the model depicted was the exact same model that I had. Installed in May '96 and working perfectly ever since I should add. I was therefore motivated to phone the utility and see what their figures were for an 18cu-ft fridge consuming 683Kwh/yr - which I admit is not stellar performance in this class. Well, this otherwise know-it-all authority could not supply any financial proof of savings or ROI and said I should check with the metal recycler who's 1-800 number was in the promo as it is they who actually run the program. Spokesperson for the recycler said his responsibility was merely to get my address and pick up the fridge - which, incidently, must be in good working order??? Huh, the nerve. As for Mr Kettle back there. I use a 800W microwave to heat water for instant coffee, and a gas range for an actual kettle when I make tea. But that's just my english heritage. Regarding HVAC, I'm retired so it's safe to leave some windows open with bug screens in place most days. I will allow that there are days when humidity dictates employing the HVAC to dehumidify the house before things become unbearable. In California I think this may not be an option. A suggestion that Lead Acid batteries working out at $100/Kwh would be a cheaper solution met with disfavor by a friend who had served as a volunteer fireman. Apparently this type of backup solution has been known to have caused call-outs after someone was puttering about in the basement, while smoking and in the vicinity of cells which happened to be gassing at the time. TESLA's competence in thermal management of lithium ion energy storage enables safe in-home installations that will hopefully promote changes in the HVAC industry. Why not DC current compressor feeds ? Then there's the problem of 110vac LEDs, why not change to 24Vdc lighting circuits at the breaker/fuse box? Going forwards for the power receptacles, what really needs to be operating on 110Vac that now requires upwards of 50 receptacles in the average house ?
HG, spot price silver $16/oz spot price copper $2.76/lb says it all, assuming 40oz in an axial rotor. Even so it was interesting to find out silver has a conductivity / specific density product ratio which is not as favourable as copper due to the overwhelming greater density of silver. Regarding motor type, Musk has been adamant in favour of asynchronous working from the start. Both types require digital tach feedback for field oriented design but the synchronous motor requires stator sensors which must be accurately phased to the absolute rotor position. While it is true that asynchronous motor software is a little more difficult and there is the additional requirement for realtime modelling of the rotor temperature since a 100 deg C rise in temperature will increase the rotor resistance by about 30%, the robust nature of the 4-pole induction machine makes it a good choice for automotive powertrains.
Well if it can survive more than five years and hostile under the hood conditions without a thermal management system.... I was thinking that cold cranking of today's engines assisted by computer controlled ignition and fuel injection have already made winter starts significantly less problematic. That vulnerable first early morning start could be avoided, IMO, if all vehicles for use within the snow belt were equipped with block heaters. Even so subsequent starts with a warm engine and lower friction are less demanding on the battery anyway. Someone must tell me what I am missing since Li-ion is going to be priced well above $250 per Kwh. All the cars I have owned in the last 40 years have had the block heater supplied as a dealer fitted option. Here in SW Ontario we have come away with a record 48 days this winter where the temperature never rose above freezing.
The installation of 500 chargers through a government program seems to confirm what Mariana Mazzucota was saying on TVO's Agenda last week and in her book "The Entrepreneurial State" regarding the Private Sector Myth. I expect that once the government funded infrastructure is in place there will be some capitalist ready to grab the keys and drive away in order to privatise the profits having ensured that practically all the initial costs have been borne by the social sector. Mark my words. On a lighter note I see that California lawmakers have already set up laws to have landlords provide a proportion of outside electrical outlets so that apartment dwellers who have little political power don't get "left out in the cold" so to speak.
China has to recognize that they have a population problem as we equally are having in the West. Our aging population is being tasked with shouldering the cost of new public transportation infrastructure to be ready for future generations and avoid the gridlock we have today. Planners for the LRT project here have already predicted a 50% population increase in our area by 2032 which will no doubt necessitate further expenditure to be extracted from the existing population at that time for the 2055 predictions.... in a never ending circle. Perhaps it is time we revisited a different solution to this unbridled population problem. One rational approach could be to incentivise young couples to remain child free perhaps removing education levys on the property tax rolls for those without children comes to mind. There is likely to be a shortage of well paid jobs in the future and we are already seeing this in employment figures which show the number of new jobs being created is increasingly for low paid employees. The concentration of Telecommunication Companies is now being challenged by our government which yesterday made an order that in Canada, Cable companies must limit their charges for basic services to $25/month. That's what will become increasingly necessary if you support the idea of TV as being the opiate for the masses in lieu of inadequate disposable income.
It is the HEV version NOT the PHEV version that has the 10kw battery. Said system comes with a weight penalty of 20Kg. as DavidJ just pointed out and we would need to know what the kwh is to make any judgement here. The HEV battery, unlike that in the PHEV, will likely have electrodes formulated for POWER rather than ENERGY. It compares favorably in comparison with the Prius battery which is using twenty year old NiMH technology, weighing in at 100Kg though still able to supply 21Kw albeit with a capacity of merely 1.3Kwh. This salute to the oil industry may never make it to market with the diesel engine being discouraged for personal transport in Europe. In fact the growth of public charging infrastructure may make this bridge technology obsolete. Come to think of it have there been any successful mild hybrids out there ? At this late stage they seem to be more like compliance vehicles.
Alex , I ask that perhaps you could take some of these OT ideas to other places where they may find a more enthusiastic setting. Have you tried Endless Sphere ? Also DIY Electric. These will be my final comments here. I have tried to register in the discussion board. There is no register button in my browser so no go there. 5-Phase although of theoretical interest does require some inverter to motor topology changes since there are obvious ramifications to having legs separated by 72 deg. Also I have no idea what ZF's planetary twin ratio device is about. Assuming an automotive drive is under consideration, then unlike an ICE there never should be the need to have to spin down an IM in order to enter a coarser gear ratio when you want to go faster and thus avoid an RPM range that may exceed the motor's mechanical limits. Such a condition can only mean that the motor specified was seriously undertorque for the application. The max rpm of any machine should be just below the point at which the machine's rotor is likely to grenade. The reason is that motor power is proportional to rpm and since aerodynamic losses do not diminish with increasing vehicle speed it is preferable to gear the motor for its max rpm to coincide with the top road speed. That said, some electrical designs experience torque roll off at high speed. This is because the stator winding pattern has been deliberately arranged to present a high V/F (Volts per Herz) ratio to the inverter. Motor torque is proportional to the product of motor current and V/F ratio. Clearly a larger V/F means an equivalent torque can be still be produced but with a smaller current. It is a popular trick that is used to enable the current rating of the inverter transistors to be reduced. The drawback is that a large V/F ratio will have the motor present a high back EMF at relative low rpm such that a period of constant power is entered followed by another area where the torque begins to drop inversely as the square of the speed. To maintain some semblance of performance the ability to select a gear ratio that will slow the motor rpms relative to road speed will bring the motor out of voltage saturation and generally the restored motor torque will temporarily compensate for the coarser ratio of gear now employed. There is an elegant solution so that all this trouble can be avoided in the first place if the motor is wound for a low V/F and used along with an inverter with oversized transistors which is standard practice at Tesla. As a point of fact whereas a general purpose 480V 60Hz motor will have a V/F of 8.0, the corresponding frame size Tesla motor is estimated to have a V/F of 0.25, meaning that for equivalent torque the Tesla motor will have to draw as much as 32 times more current than the previous motor. A situation which is not problematic since the Tesla inverter is well equipped with no less than 850 amp transistor ratings.
@Alex _C interesting links BTW. On the electrical side I can answer some of your questions directly. Going forward maybe the GCC discussion pages should be used since topics that fall off the Home page have less accessability to the general user base as time goes by unless you have happened to have saved the exact URL of course. A discussion on AEVA (motor & controllers) entitled 14,000 rpm machines considers PM versus Induction. It was brought up in the first post with the expectation that PM would be summarily dismissed. As it turns out there was considerable interest perhaps as long as the Toyota Prius and Nissan Leaf continue to use them I suspect. For tow trucks and forklifts which are mostly used as mobile positioning systems they will always be a good choice. My experience is that 5-phase PM machines manufactured by VEXTA are mainly confined to applications known to be sensitive to normal torque ripple. The robust nature in both temperature and overcurrent points to the 4-pole per phase induction motor as optimal for automotive usage. The 6-pole per phase may produce better torque/mass ratio but needs research. Greater than 6-pole may be OK for the industrial market but has slotting issues which obviates its use with with smaller automotive frame sizes. For 4-pole motors, excitation frequency = RPM/30 Hz Copper loss is not a consideration in the stator. Electrical loss in the rotor -since that's where all the electrical power ends up after it crosses the annular gap- is key so copper rotors are mandatory but most industrial motors (premium effcy) are now using them today, see the Eurotherm catalog. Magnetic losses generated by hysterisis and eddy currents become less a consideration when manufacture includes the use of thinner laminations and the finest electrical steel that Accelor-Mittal can make. Simply put, the Tesla Model S with its latest $140k flagship P85D 5 seat sedan with insane 3.1 secs to 60mph exemplifies the induction motor as the go to solution for BEVs. Whether Tesla has found the optimal mechanical transmission layout where durability at high power will not be an issue remains to be seen. Tesla has seen problems because it is the only company pushing out sufficient quantities that even one in a hundred can no longer be considered as an inconsequential occurrence.
I have direct experience of comparing transverse electric motor mounts versus those using longitudinal coupling. Dyno results showed conclusively that turning power through 90 deg from a longitudinal motor, as is shown here, was proven to be the inferior choice. That aside, the architecture of using two motors, despite the incremental cost factor of the dual drive, looks to be an excellent idea. The ability to dispense with the differential components as done here, may avoid a problem that Tesla seems to be having with their two stage reduction box. Incidentally any visit to the Tesla website soon reveal it to be inhabited by moderators who are extremely sensitive to any fault details being released with regard to their gearbox, naturally speculation is inclined to be rampant. My take on the problem is that moving from motoring to regen braking is so fierce that the differential spider gears are being given a hard time. Fast changes in slew rate aren't problematic until you pass through the dead band and hear the clunk signature as pressure is suddenly exerted at the reverse face on the gear teeth that are already engaged. In fairness it should be pointed out that very few vehicles have exhibited this symptom straight out of the gate. So it could be exacerbated by driver style as much as anything. Many of the owners are A-types who don't appreciate they are confronting bleeding edge technology and while $140k of their money is on the line they resent even the slightest suggestion that perhaps they should not do pretty much as they damn well please. Avoidance of the gear lash within the differential requires consideration of the differential system being replaced by a dual drive system. It will become apparent that the amount of gear hobbing remains the same. The left/right wheel axles are terminated in gears which are standard helicals rather than bevels. If it is assumed that a two stage reducer layout is to be maintained then the final differential gear containing two, perhaps three spider gears is eliminated entirely with the placement of three new gears, one of which would be the motor pinion for the additional motor. The High RPM motor presents another interesting design avenue. Higher rpms effectively increase machine power density and permits the use of lighter motor frame sizes. Notice the stipulation on lighter rather than smaller frame sizes since it facilitates the options of either higher power or increased affordability. BTW Tesla has tested one of their induction motors for 24 hrs @ 24000 rpm. What is not known is the frame size and whether it was performing under load. Finally the "shared housing" may not be the best approach. Again Tesla uses this highly integrated approach and in my opinion it has been a disaster as far as maintenance costs go. Of course solid failures justify dropping out the transaxle but some complete transaxles were exchanged when just a shim needed replacement. Automotive training usually governs that area of how things are supposed to work, the experience to identify problems in these early years will take time to acquire by a dispersed group of people. In the meantime the ability to disassemble major components in situ is going to be a consideration if the cost of electric vehicle maintenance is not going to go through the roof.
Thanks for the responses. You are obviously more adept mechanically than I. Perhaps I ought to have stopped by my local transmission shop for their take before I posted. My life experience through aquaintances, who have kept older vehicles on the road, is that despite having immaculate interiors, no dings nor any signs of exterior rust at 150k kms will never be enough to prevent these vehicles from going to the crusher when their transmissions begin to fail. They just shrug and start searching for the next and newer CPO. CE88 , you countered mechanical reliabilty by introducing the question of EV battery longevity. I have to agree that this is a sensitive matter over on the Tesla Motors forum. There are a number of members on that website who are also owners of the Model S . Several of the latter group seem to be unaware that they are still in the early adopter phase for vehicles of that type, specifically the 300+Hp electric sedan. Regardless of that they persist in clocking up much more mileage than the average 1000 miles/month usually demanded from a typical gas car. One particular character increased his odometer reading by 17K miles in just four months ! Now we know that for the S85 (denotes the 85Kwh battery version) the complete powertrain warranty is eight years with unlimited mileage. The problem is trying to get a fix on exactly what this warranty supports in terms of battery failure. Leaving aside the obvious pack total failure, how the battery pack warranty intends to deal with a pack whose charge retention is beginning to deteriorate needs to be answered. On this Tesla is somewhat vague. There are of course a whole bunch who are quick to dive in and attest to their packs proficiency after 40K miles etc etc. Then there have been extreme cases that allow Tesla to extend some goodwill and do a full replacement. But there are now increasingly more cases where the company factors in the usage delivered and replaces the pack with one of similar wear. In some of these cases customers have turned around and demanded a pack which is capable of the original mileage at delivery on the grounds that so_and_so has reported that his battery is only a couple of miles down after a full year of use. That of course is the problem. Perhaps so_and_so has a commute where he doesn't exceed 45mph whereas the other profligate owner likes to bury the needle so to speak. Of course the console display is merely a computer prediction based on best practice modelling and headwinds and low ambient temperatures will also eat into the rated miles as displayed on that console. For the future maybe they should consider the pack's Kwh storage - let the supercharger decide - at ownership change and leave the car and the rest of the powertrain out of the equation. Finally mechanical transmisions are based on a mature technology with lots of history whereas battery packs are only on their second iteration. Time will tell.
CheeseEater, you reminded me that most, if not all transmissions (since 2000 at least) just get rebuilt at a remanufacturer, it cheaper to just swap for a rebuilt. I agree that back in the day, repair of three-speeds used by those 350 cubic inch engines was indeed practicable. However, following the advent of five speed or more sophisticated transmissions with their electronic interface to the ECU it is no longer so. At least not unless significant proprietry technical resources are made available. I would have to rebut that the more pricier rebuild may be the option for late model vehicles, but often or not, particularly outside of the warranty, it is increasingly becoming a deal breaker with older vehicles. ZF provides complex mechanical solutions in a world that is intent on moving the complexity part into the electronics where the reliability improvement is a thousand fold. In this world only the simplest mechanics will exist. On this note I predict that even Tesla will eventually eschew the differential final gear that is possibly giving them the occasional gear lash problem (from what I read) in favour of a slightly more robust twin motor drive. In manufacturing you strive for repeatability and reproduceability. That these goals are more easily reached with electronic systems is probably an understatement.
ZF has to keep current with its clients and those clients continue to specify and purchase something they understand. Another recent example of this is to see how successful auto dealerships have been at handling the sales of electric cars. Not. Of course it is one thing to have machines designed by those with Doctorates but out in the market the transmission repair shops don't have that luxury. For that reason it has been stated that the increasing sophistication of these devices has resulted in more than 50% of them being uneconomic to repair.
It is not a foregone conclusion that a self-driving vehicle would ever perform more safely than an experienced, middle-aged driver. Do I detect some ass covering here ? But OK, if that particular demographic is to represent the benchmark human driver then I, for one, would be quite satisfied if the autonomous vehicle could perform even as safely as an experienced, middle-aged driver. And by the same token it would follow that its ability should likely surpass the skill of all lesser drivers as well. You know, those drivers responsible for the road deaths of 34,600 people last year in NA. Would you agree ? As we like to say here - Good enough is not the enemy of perfect.
A rarely discussed problem concerns the fact that most of the superior chemistries are said to have unacceptable self-discharge rates when used in a 12 volt standalone application. There is also the cost factor of Li-ion batteries ~$240/Kwh whereas the average 0.9Kwh Pb-Acid goes for around $100.
KERS favours vehicles whose drive cycle demands frequent stops. IMO for cars, the adoptiion of a driving style that includes coasting when the opportunity arises would probably yield better results.
@mahonj , I have to disagree. Tesla's build out of Supercharger stations is a game changer. Since we can assume that you should always be leaving home with a "full tank" the only decision is whether you will need to be visiting a Supercharger at all. And for most longer trips that comes down to whether it is convenient to visit the Supercharger shortly before your arrival or shortly after your departure. Electric saves you never having to visit that special place - the gas station - or every three months that other special place - the oil changer. At a certain point it will be the gasoline user who will be needing to use a mobile app to find the nearest gas station that is still available. Whereas for an electric vehicle there will continue to be the potential availability of millions of outlets for energy.
Just read your post Henrik, regarding PHEVs. That GM should be trending to BEVs sooner rather than later. My sentiments also. The article refers to a driver group who achieve a higher AER than the 35 miles which the EPA predicts. It seems to be the reverse of range anxiety that has these drivers playing a new game of driving conservatively in order to prevent the ICE from starting. That said, I'm sure there is a similar group out there who would like to experience the pros and cons of living with a two cylinder engine as a range extender also.
@ E-P, Thank you for providing us the link, very useful. I have to say that it is probably the best aggregation of data to the subject that I have seen so far. Thanks again.
A well-to-wheels analysis of the use of natural gas for passenger vehicles should involve the BIG picture which here is not the case. Their model seems to align with the old school method of distributed electrical power. To most of us it should be irrelevant how efficient megascale generating plants can be made if the residences - outside of which these passenger vehicles are parked - happen to have their space heating provided by open flame natural gas furnaces and as we all know these forced air systems have a thermodynamic efficiency of ZERO per cent. A serious W to W study should at least consider home generation of electricity. You know, CHP.
Davmart, I would like to speak to your comment as one who has relied on public transit until recently and is also a very minor stockholder in Tesla Motors, to which you just made an oblique reference. But first, on public transport. When service frequency is sub ten minute, public transport is akin to being chaufeured around town by the government which is of course somewhat fiscally responsible, I suppose, in hi density areas. The problem is that when authorities are charged with providing a suburban route at a price that makes financial sense it ends up with you, the consumer, being constrained by a 30 minute service with the circle route that puts you on the twenty minute neighbourhood tour you would rather not make. It's really hard to be anywhere near cost effective when the chauffeur has to be paid at a rate consistent with possessing an equivalent AZ license (about 3 times minimum wage against what most of the passengers are probably earning) while motoring around in an eight ton vehicle. Outside of North America some transit authorities are addressing the cost issue by adopting the use of microbuses, for their feeder routes I assume, similar to the airport shuttles with which most of us are familiar. In the mean time private companies here in NA are not eligible to bid on the established routes which are operated by members of a public service union. There is also the hidden cost, paid for though property taxes, of the significant damage these larger vehicles do to the roads they frequently travel. Tesla will continue to make cars for the rich since this early stage company needs the high margin sales while in expansion mode so they can be ready to support the market when the demand escalates for the entry level luxury models at around $50K sometime in the next four years. Despite the fact they sell product that meets current legal requirements, I too would like to see a world where 7sec cars and 100mph represent the upper limits on speed and acceleration. I apologise if these comments seem facile to you. I have had to put up with comments on the Tesla website where there seems to be a breed of car enthusiasts out there who want every car Tesla puts out to be a track car. You can see the frustration when another poster responded "so if I have got this right you are wanting almost the same performance as a Model S has now but at $50K, in other words then what you're really asking for is for Tesla to knock $40k off their price for a Model S and you would be good to go !! LOL"
Good video. Thanks. I posted a link to it from Tesla Motors site. I can't make them smarter over there so at least I can assist them to be informed ! The video runs for more than an hour. Here's what I took from it. The video begins with Prof Dahn of Dalhousie U. discussing battery longevity issues brought on by charging. It is known that charging cells when cold is beneficial to slow the formation of a coating on the surface of the cathode material. Consequently a useful strategy is to ensure a limit to the time that the cell is heated by the charging process. It follows that speeding up the process at a rate of around 1.5C gets the process over quickly so that the cell can be cooled immediately and so curtail the time window for the coating to form. Throughout this video, made last year, Prof Jeff Dahn makes several references concerning Tesla Motors. In particular mention is made that one of the original researchers, Aaron Smith, had moved over to Tesla in March of 2012. At Dalhousie, Smith was involved with the assembly of test equipment to measure the exothermic generation, at the tens of nanowatt level, during the parasitic formation as separate from other heat sources within the cell. Prof Dahn goes on to say that apparently discerning the difference between microwatts and nanowatts is key in predicting the coulomb efficiency drop off. Of course when the cell cathode is totally plastered -so to speak - and drop off in performance now becomes more rapid, well that particular condition remains harder to quantify. However the enhanced measuring techniques mean that you don't have to put a cell through thousands of cycles to determine when its useful end of life (80%) is likely to be. Further insight into cell design was given that it is not just one compound that improves longevity but the synergism of several additives and that is making scientific progress difficult. It appears that a twentyfold increase in cycle life can be made by a mere 1% addition of one new substance providing other electrolyte additives are present in the right quantity. On the other hand if you're not optimising the additives but think that you can just try to figure out the mechanism of why they work the way they do then you're CRAZY ! That's with the equipment now being used at the current SOTA, I am assuming. Bottom line. As a first choice it is actually more preferable to be using Superchargers than even L2 chargers but only if the cells are cold. Racing between superchargers thus needing to visit more supercharger stations on your route - assuming circumstances permit - is not so much a good idea, unless the Thermal Management System has been able to precool the pack. Charging from 110Vac won't introduce much heating, of course, but it might be better to be doing it when the battery is known to be cold. I guess the use of these techniques requires a name analogous to hypermiling.
Otis, from your previous two comments I see that you are pushing for larger batteries until battery tech catches up. Here's the problem I see with that. When is enough enough ? I think even at $150/Kwh the 24Kwh Nissan Leaf would have a $3600 pricetag. Not surprisingly there are many out there who are demanding double that for what they consider to be a viable car. However the case for future transport should be that "the purpose of cars is to primarily transport people and not the carriage of tons of chemical material through the streets". A single occupancy Model S weighing over 4000lbs is not the answer when some are purchased to gain unbridled access to the HOV lanes. My deal is with the Superchargers which permit range extension for any size battery and the way in which they are being introduced to the market. In particular the free use aspect. When free use is permitted on anything, like supercharging in this case, then most people are going to want to capitalise on it. Again human nature being what it is, a better strategy may be to impose a minor fee per use. Overtly this stategy might discourage bunching up around supercharger sites which is very likely to occur as the population of Tesla vehicles escalates, while achieving the underlying purpose of serving to avoid or mitigate any possible, but as of yet unproven, acceleration in the deterioration of battery capacity. A condition vehemently denied by Tesla supporters and something I hope will turn out not to be the case when more data is available. However you have to be aware that a negative outcome carries the risk of additional financial implications to Tesla since the company has pledged to support the resale price to the original owner. The idea is that providing a backstop on the residual price will enhance the value of the brand and encourage future sales. Meanwhile at Tesla, software designers may be taking advantage of the vehicle knowing - through the touch screen - when the vehicle is about to be visiting a SC site and will use the intervailing time by supercooling the battery enclosure in anticipation of the event. This proaction should ameliorate the effect of heat which will eminate from those 8000 individual cells during the subsequent sustained recharge at an ~2C rate. Marketing at Tesla has taken the stance of saving on cost and to rely on word of mouth advertising, in which case they might try an assurance to remind consumers that " Whenever you leave home you start off with a FULL TANK". A sentiment that costs nothing but may dispel thoughts of range anxiety. Is it also too much to ask that marketing will better connect consumers to the effect of speed on range ? I find it somewhat circumspect to benchmark range at 55mph in order to enhance vehicle capability on paper. Is it safe to say that no one who has paid out close to $100k for a Tesla is going to be satisfied by driving it at that speed unless, of course, they happen to be in a 40mph zone ?