Joseph, I'm not sure where you heard about or came up with the idea about any "conspiracies" between Tesla and its various suppliers, but I haven't heard of any.
It is true that Tesla has had continuing transmission problems and has been quite open about discussing them. What they have not been entirely open and forthcoming about, at least in public, are their battery problems. Please see some of my previous posts in the last day or two on this subject, but in case you missed them, I will try to present some of the points here again. Some Tesla customers, based on where they live and their climate, have been told to expect up to 10% capacity loss per year on the battery pack, and hence up to 10% loss in range per year. This is entirely consistent with the well known, well established experience with LiCoO2 batteries going back over 10 years now, as previously discussed. Yes, that is energy loss (and hence range loss), not power loss, or at least not noticeable power loss throughout most of the SOC range. But this phenomenon will actually manifest itself in some degree of power loss at the lower end of the SOC range. The reason for that is because the factor that drives this energy capacity loss over time is an increase in impedance over time, so that will be most visible in terms of power loss at the lower end of the SOC range. Another big problem with Tesla's battery pack, that is now fairly widely known and discussed in industry circles, and as previously discussed here, is the fact that Tesla is now underwater on the cost of vehicle, with their cost now exceeding the $100,000 price that the first 100 buyers prepaid for it, this being due to the doubling in price of cobalt over the last year from $26/lb. to now over $52/lb. and the resulting large increase in the cost of the battery pack. A related problem is that the market for 18650 LiCoO2 laptop cells is extremely tight right now, and Tesla is reportedly having trouble sourcing sufficient volume, as are all the laptop makers. Part of this is due to further recalls of these cells due to continuing safety problems with them, most recently from Panasonic with a big recall. The growing awareness of the safety problem and danger of these cells is becoming an increasing publicity and marketing problem for Tesla and AC Propulsion. As I mentioned previously, AC Propulsion has already had a battery pack fire with their 18650 LiCoO2 packs. And as previously stated, no major automaker is willing to use this chemistry or these cells, and the US government's top battery scientists have said they're not safe for use in electric vehicles. One of the biggest problems with Tesla's and ACP's battery packs has just been discovered in the last year, and that is the realization that cylindrical cells are the worst possible form factor for use in EVs and are basically not very well suited for EV use. The reason this is just being realized in the last year is because previously, most testing of these cells was bench testing done in labs, under controlled conditions, but in the last year, a lot more testing in the EV industry of these cylindrical 18650 and 26650 cell-based packs has moved out of the labs and into vehicles, where you have serious heat and vibration issues that don't exist in the lab, or at least the simulation of those conditions in the lab does not always represent very well the variability of what you find out in the real world in actual vehicles. Testing that has been done in the last year by OEMs has revealed that cylindrical 18650 and 26650 cells have an unacceptably high failure rate with vibration and that the end caps tend to short out, including with A123's 26650 cells, by the way. This presents serious safety problems. GM's top battery and PHEV drivetrain engineers in their Chevy Volt division are well aware of this, so much so that they are now quite concerned about using A123's cylindrical 26650 cell-based packs in their Volt and other planned PHEVs. This is a big problem and one reason why GM is multisourcing battery pack development contracts to several different manufacturers with different chemistries and different form factors. It has long been known that the spiral-wound design of the cylindrical form factor has the worst thermal properties of all type of cell designs. Pouch and prismatic form factors are much more efficient thermally. This is readily apparent and just common sense if you think about it, because with a spiral-wound cylindrical design, the heat generated in the center of the cell has a long way to travel to get to the exterior. This is not a problem for the application for which cylindrical cells were originally specifically designed, which was for consumer electronics, i.e. cell phones and laptops, with their constant-current, very low power draws. But it turns out that cylindrical cells are a very poor design and not very well suited for the high-power, variable-current demands of an electric vehicle. Again heat and vibration are the issues here with EVs, neither of which exist in cell phones or laptops, ... for the most part (unless you leave your cell phone or laptop sitting in the front seat of a car parked out in the hot sun, in which case they have been known to catch fire and explode ... sort of a case in point). In an EV, with its high power and variable current demands on the batteries, heat is generated in those batteries. In addition to the need to dissipate that heat, which cylindrical cells do very poorly, this constant heating and cooling causes the cells and their casings to expand and contract. This turns out to be a problem for spiral-wound cylindrical cells, as you can imagine just by thinking about it, and is another failure point and weakness of them. So battery and electrical engineers working in the EV industry are now discovering all kinds of problems with cylindrical 18650 and 26650 cells in EVs, which of course were never designed for that purpose and application, so this shouldn't come as any surprise really. Finally, here is the problem that I referred to yesterday with the lack of economies of scale of Tesla's and AC Propulsion's battery pack design of hand-assembling and tab-welding many thousands of 18650 cells into a vehicle-sized battery pack. This is an excerpt from a private discussion thread between 6 battery and electrical engineers who work in the EV and related industries: "The big problem with this is that small-format 18650 and 26650 cells are only just barely *marginally* economically viable for small-scale serial production of 20 vehicles per year (which is ACP's current production rate with their eBox) to a few hundred vehicles per year (which is Tesla's anticipated production rate, starting this spring) for the tiny niche of well-heeled early-adopters who are willing to pay $75k (eBox) to $100k (Tesla Roadster) for a showcase trophy BEV. But tab-welding and assembling thousands of 18650 LiCoO2 (ACP and Tesla) or 26650 LiFePO4 (Continental for GM with A123's cells) cells into a vehicle-sized pack for a BEV or PHEV will *never* be economically viable for large-scale commercial production on the scale of a large automaker like GM, which has announced that it intends to produce tens of thousands of PHEV Volts per year right from the first year (November 2010 production launch date announced but will probably end up being more like 2012 in reality). Tab-welding and assembling thousands of small-format cells into a vehicle-sized pack is an extremely labor-intensive task that will never work for mass-production, not to mention the enormous EE challenge of designing and integrating a complex, sophisticated BMS to manage all of those thousands of cells in a massively parallel-serial configuration." Best regards, Charles Whalen Delray Beach, FL > On Sun, 9 Mar 2008 23:35:15 -0400, Joseph T. wrote: > >> "This fact, as well as other problems with Tesla's battery pack, is the >> real reason for Tesla's continuing delays (with the transmission >> problem excuse being largely a smoke-screen)....Tesla's senior >> executives have admitted to at least some of their customers >> (from my communications with them) that they expect the battery pack's >> calendar life to be about 4 years and definitely need replacing by 4 or 5 >> years." > > A smoke-screen? So this means the multiple different transmission > suppliers and different transmissions have been part of some > conspiracy? Tesla for sure has had two different transmissions (the > two-speed and the one-speed, both which can be verified because > auto-magazines have tested both) and are now working on their final > third one. Tesla Motors has actually, explicitly stated that batteries > haven't been a problem for them at all. they made a whole blog post > saying that the battery pack wasn't the reason for delays. On the FAQ > section, they claim a loss of 30% performance after 5 years and 50k > miles. According to ProEV, they said this 30% loss should only be in > energy capacity, not power output. _______________________________________________ Florida EAA mailing list [email protected] http://www.floridaeaa.org
