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Thread: Tesla cars allowing batteries to become fully discharged?

  1. #31

    Default Re: Tesla cars allowing batteries to become fully discharged?

    Amusingly in colder climates the grid would be able to handle it better, as people already plug in their internal combustion engine powered cars to the grid before leaving to or from work, in order to preheat the engine to reduce wear&tear, and cheat the windows to reduce the ice thickness on them, but on the other hand the amount of power you'd need for onboard heating would drop range somewhat

  2. #32
    Flashaholic* jasonck08's Avatar
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Wrend View Post
    Which cells did they use that only get 300 cycles?



    If this is the case, then more fully discharging, and cycle life shouldn't be much of an issue.
    Panasonic NCR18650A.

  3. #33
    Flashaholic* Wrend's Avatar
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Yes, the spec sheet on those cells doesn't look all that good. Could probably get better cumulative lifetime capacity (and of course cycle life) if the cells aren't as fully discharged.

    http://www.panasonic.com/industrial/...sheet.rev1.pdf
    Last edited by Wrend; 02-24-2012 at 07:34 PM.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by shadowjk View Post
    Amusingly in colder climates the grid would be able to handle it better
    I'd definitely prefer the Leaf for cold weather duty; the Tesla's rather tail-happy rear wheel drive setup is very Corvette-like, precisely not what you'd want for inclement weather. The pedestrian Nissan with its skinny tire front wheel drive is vastly preferable for snow and ice.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    a guy in a Tesla pulled up next to me and we admired each others cars today.
    Im driving a beat 1986 Corolla GTS with a drift set up
    Ive got only 1 Panasonic NCR18650a in my car tho...
    in my glovebox light

    I think Tesla is a cool company even if there are some problems with the cars
    we still benefit from the attempt to see whats possible no matter if it fails to
    save the polar bears or make $$$

  6. #36
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Wrend View Post
    Did you know that you could charge a battery powered electric car with a relatively cheap gas powered generator and still get better gas mileage and pollute less?
    Outdoor Power Equipment makes a LOT of pollution. We're talking an hour of mowing is something like driving your car 300 miles. And not to mention you'd upset your neighbors running an open frame 5.5KW+ generator every night to recharge your electric car.

    We've got a cheap 5.5kw Harbor Freight unit for power outages. It's a great generator. Will blow through 5 gallons of gas in 8 hours running at 1/2 - 3/4 capacity. We got to test that out during the Halloween snowstorm in the Northeast. So I drive my car 100 miles on 5 gallons of gas. That's, what 20 MPG? I get better than that in mixed city/highway driving in my 360hp car. On straight highway I can get up near 25MPG. And that's an AWD car that weighs about 4000 lbs.

    Oh, and Natural gas generators are about the same as the fuel contains less energy than gasoline.

    A Diesel generator would be the way to go but you have to feed it somehow and it still doesn't get around the fuel and sound needs/issues.

    Electric cars would be great if the infrastructure was there but it's not.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by jasonck08 View Post
    Not only did Tesla forget to install a Low voltage cutoff, they also made a mistake in choosing to use cells rated for ~300 cycles.

    The car gets 200 miles max per charge and the cells in the pack are good for 300 cycles tops. So that means that if you exclude the fact that the battery discharges significantly on its own, and you do the math 200x300, that means the car is good for 60K miles max before needing a new battery @ $40K+.

    So assuming there is no additional maintenance besides tires and brakes in the first 60K miles, you are still paying likely around ~45K in maintenance for driving 60K miles. Not only that but the fact that it discharges ~25Kwhrs per week. 25Kwhrs is going to cost around the price of a gallon of gas. And thats the price for just storing the vehicle! The only green I see in the tesla is the stack of money you hand over to buy and maintain one of these cars.
    Interesting. Same thoughts I have been having with this vehicle. I have been looking into the Model X that was just announced and my concern are the costs after purchase.
    Last edited by cue003; 02-25-2012 at 08:01 AM.
    -- CUE

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    Flashaholic* Wrend's Avatar
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by itguy07 View Post
    ...
    The fuel gas generator would need to be optimized for the task, but what I said is definitely doable. Maybe not with your setup as is, of course.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Putting aside protection circuitry, using 6831(?!) 18650s instead of maybe about 120 of these is just a brain-dead decision. Same amount of energy, less than 1/50 the number of cells to assemble into a pack, 2000 cycles instead of only 300, safer chemistry, costs about the same. OK, the pack would be a few hundred pounds heavier, but with regen braking weight doesn't significantly impact range. Their engineer must have been asleep at the wheel.

    And the grid is plenty ready for EVs now. We're not going from zero to 100 million EVs overnight. We could beef up the grid where and when needed as we go along. I suspect also that solar power will become mainstream in the same time frame as EVs, and lots of people will be charging their EVs off solar power, making the whole grid issue moot. An interesting factoid is that petroleum refining is the single biggest user of electricity in the US. As you go to EVs, more and more of that power will be freed up for charging.

  10. #40
    Flashaholic* LEDninja's Avatar
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    I learned a new word today.

    In the last 2 years I BRICKED some of my lithium-ion flashlights.
    When recharging my Li-ion cells I always check the voltages first. The thing that surprises me is the voltage of the cells gone bad are at 0.0V to 0.08V. I expected to see some at ~2V or so. Nope.
    The last one the protection circuit tripped and I was unable to untrip it. Won't charge, won't discharge, voltage measures above 3.6V.
    I have tossed over half a dozen cells so far. (18650, P18650, 14500, P14500, 10440) No big deal - mostly DX types. Luckily I do not have to spend $40,000 to replace them.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Wrend View Post
    The fuel gas generator would need to be optimized for the task, but what I said is definitely doable. Maybe not with your setup as is, of course.
    Not really. Piston engines (even Atkinson cycle models like which are found in most hybrids and the Volt) are not that efficient. About the best we've got now is turbine engines (Jet engines) and even those are way less efficient than, say a coal or natural gas plant. And I won't even discuss the maintenance that turbines need.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by jtr1962 View Post
    And the grid is plenty ready for EVs now. We're not going from zero to 100 million EVs overnight. We could beef up the grid where and when needed as we go along. I suspect also that solar power will become mainstream in the same time frame as EVs, and lots of people will be charging their EVs off solar power, making the whole grid issue moot. An interesting factoid is that petroleum refining is the single biggest user of electricity in the US. As you go to EVs, more and more of that power will be freed up for charging.
    I don't know where this capacity will come from. No new coal plants will be built in the USA. Few natural gas plants, and even fewer nuke plants. Solar and Wind are pipe dreams for the most part at this time. Spend millions on solar for low capacity or millions on wind and still have lots of expense to maintain it. Hydro is about the best we've got but the environmentalists don't like it because it bothers the fishes.

    And then we have the transmission lines that were never sized for this. Who pays for the expense to upgrade the grid?

    Not saying it's impossible but it's a lot longer, harder, and more expensive than most make it seem to be.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Tesla Motors says you cannot brick a Model S

    http://www.torquenews.com/1075/tesla...-brick-model-s

    ... But, wait, it gets better with the Model S. For starters, "a Model S battery parked with 50 percent charge would approach full discharge only after about 12 months." ...

    =D~~ Kilted

  14. #44
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by itguy07 View Post
    ...And then we have the transmission lines that were never sized for this. Who pays for the expense to upgrade the grid?

    Not saying it's impossible but it's a lot longer, harder, and more expensive than most make it seem to be.
    This is what I was alluding to in an earlier post. Let's talk about the GRID for a minute.

    Actually it's "GRIDS" (East, West and Texas) One of the things all three grids have always had in common is that from an engineering point of view they were each designed to be a very reliable link in a "vertically integrated" plan.

    In the old days if you had the bucks and the inclination to get into the 'electric business' you had to provide everything pretty much from start to finish to not only create the electricity but also to deliver it to your actual customers. Vertically integrated just means that the company took care of nearly all aspects of production and delivery in house. This is a very important point. Think about it. You make the power and you own everything it takes to deliver it, dare I say, to the last mile. Ask yourself how you would take care of that investment. What they did was to design it very carefully and maintain it with care.

    The problem is that that was all a long time ago and we no longer live in that world. The environment for that old business model no longer exists... The power companies were 'deregulated' long ago and that changed everything about the way the grids would be utilized from then on. Vertically integrated grid design stopped in it's tracks. Bearing in mind that the grids were designed as closed, vertical systems it is interesting that we now rely on them and fully expect them to interact with each other at higher and higher capacities and route power from region to region as cities go into and out of 'peak times' and the rates change. They are always changing. If we had grids that were designed to do this it would probably be wrong headed, but at least it would be doable.

    Short story -- we don't. Put it this way, we are not only running our vertical grids in a horizontal mode but we increase interconnectivity and load every year! No, the grids are not fine and they have not been fine for decades.

    Longer story -- the other killer way that deregulation TOTALLY changed the landscape for the power companies was to completely remove any incentives to spend even an extra cent on maintaining their distribution lines. Why should the shareholders have to pick up the tab for wear and tear on the deregulated lines when by law they have no control over who uses them?

    Slowly a picture emerges -- like a one two three punch:


    --- Deregulate. Begin running grids completely backwards from how they were designed.

    --- Remove all incentives for the thoughtful, loving care those grids received under their pre-deregulation operations.

    --- Put entire system under increasing load every year...


    What could possibly go wrong?

    Here's the deal-- when it gets hot out and the power goes out in the city, it should not stay out for two or three weeks. I'm getting the feeling that there's a lot of people who don't pay much attention to long term blackouts unless they are in one. For the memory challenged, try this Google search:

    http://preview.tinyurl.com/7jzmdjw

    It didn't always used to be like this.

    As I alluded to in a previous post, we do not even have a plan for better grids than the old, unconnective, whimpy grids we use now.

    We seem to be so busy making our grids do more and more of what they were never planed for and we can't muster the collective will to even begin to protect the transformers in our distribution systems from solar storms. (Google "Carrington event") One of the things I learned from Katrina is the sad fact that many, many transformers are custom made to spec and require months to replace in a Katrina sized event. In a Carrington sized, worldwide event even the cars may have to wait years for the transformers to be replaced.

    So, no, the grid is not in good shape.
    Last edited by Sub_Umbra; 02-25-2012 at 11:18 PM.

  15. #45

    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by CKOD View Post
    it loses 50% of its charge in 1 week? with a 50+ KWh battery pack, thats ~150 watts of load constant. Thats definitely not energy star compliant I wonder what they are running, battery heater etc? maybe understandable in a cold climate, but not a temperate one. Also shame on them if they cant manage to eek out 150W to maintain the car over a 100' extension cord, thats only 2A or so after charger inefficiencies.
    As I recall, any time the Roadster's pack is above 50% SOC, the coolant pump runs continuously (even if parked). At least that was the case fairly early on.

    Not exactly great for efficiency. Perhaps necessary for commodity 18650 cells in that application. I've heard the newer cells Tesla will be using are improved. Hopefully they don't require quite that level of coddling.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by itguy07 View Post
    I don't know where this capacity will come from. No new coal plants will be built in the USA. Few natural gas plants, and even fewer nuke plants. Solar and Wind are pipe dreams for the most part at this time. Spend millions on solar for low capacity or millions on wind and still have lots of expense to maintain it. Hydro is about the best we've got but the environmentalists don't like it because it bothers the fishes.

    And then we have the transmission lines that were never sized for this. Who pays for the expense to upgrade the grid?

    Not saying it's impossible but it's a lot longer, harder, and more expensive than most make it seem to be.
    The point I'm making is we don't NEED extra capacity. With an EV charging overnight in a garage to replenish the energy lost driving during the day (an average of perhaps 30 or 40 miles and 15-20 kW-hr) we're basically talking about an average daily load well under 1 kW area per household. Most people are not going to need to recharge a depleted 75 to 100 kW-hr battery pack every single day. People don't even drive ICE vehicles that much on average. Anyway, we can probably reduce the average power drain by that much just going to more efficient lighting and more efficient electronic gadgets.

    A second factor is the majority of households using EVs would be single or two family dwellings. Many people who live in apartments don't even own cars, especially in big cities. Solar doesn't seem feasible yet to replace conventional power generation but it's rapidly heading towards mainstream for power generation on private homes. This makes the grid issue moot since the power will be generated and used on site. Not everyone will be going solar, but I suspect enough households will so the net extra load on the grid from EVs will be minor.

    A third point is the number of miles driven has been declining since 2006. This was long before fuel prices spiked, and therefore not driven by high fuel prices. The long term trends here are fewer miles driven, fewer cars per household, a greater percentage of households without cars, and more households who still need vehicles moving towards one more suited to what they actually do most of the time. That in effect could mean very small vehicles along the lines of electric bicycles or scooters designed to run about town for errands. These vehicles will use proportionately less power than full-sized EVs.

    The issues Sub Umbra mentions regarding the grid are very real and must be dealt with sooner or later anyway (perhaps by doing away with the deregulation causing most of the problems in the first place). The larger point though is ICE vehicles are rapidly heading towards obsolescence for a variety of reasons (and many large cities may well ban all non ZEVs in the future), so EVs are inevitable one way or another in the short term. In the long term I suspect we will change our settlement patterns so as to greatly reduce reliance on private automobiles in general. Putting aside grid issues, many localities simple can no longer afford to maintain the plethora of lightly utilized roads which have enabled sprawl in the first place. To a lesser point the same issue is affecting other municipal services such as water, sewer, and electricity. The fewer people per mile infrastructure serves, the more expensive it becomes per capita. Those who are living away from large cities in the future may well have to live 100% off-grid. That includes losing the ability to regularly and easily travel to populated areas for supplies.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Those theories work nicely in cities and suburbs with good transportation systems but come out here to cities that do now and all that stuff falls apart. Where we're at in Harrisburg, PA pretty much is a good example.

    I'll use me and my wife for an example as I think we may represent the average family in this scenario. We both work, I 18 miles away and her about the same. Pretty much no public transportation to/from work. For me it would add almost an hour to the commute (multiple transfers) and I'd have to walk a mile to/from the bus stop each day. So driving is it for us. Want to go to the mall? That's about 4 miles away, so jump in the car. Want to go to, say Best Buy. Again, car for 8 or so miles. Dinner? If you want more than the usual McD's, Pizza, or bar food you're in the car. So we pretty much need a car type transportation as everything is spread out.

    I'd love an electric car. But at $40k for the Volt or Nissan it's not gonna happen. I'd gladly give 1 car up for an electric and save the gas car for when we go to Baltimore. I could go to/from work and do errands on the charge. But the cost is way too much when I can get a much better car for less.

    I still think you will need grid upgrades. Even with time of use which everyone is pushing. All you are doing is load shifting. So instead of me running the dishwasher, electric clothes dryer, etc when I want I set them up to go on at night. Have a lot of people doing that and you still could have a capacity crunch.

    I also think you underestimate how much power needs to recharge a car - it's a lot. I've read some that peg it as the equivalent of running your electric clothes dryer. From the Wikipedia on Tesla's Roadster:
    • A wall-mounted 208–240 V, 70 A maximum current Home Connector. This appears to be an OEM version of the TS-70 charging station from ClipperCreek.[111]
    • A portable 120–240 V, 40 A maximum current Universal Mobile Connector cable that can plug into a NEMA 14-50 receptacle and other 240V receptacles using adapters.
    • A portable 120 V, 15 A maximum current Spare Mobile Connector cable that plugs into a standard North American domestic socket.
    Charging times vary depending on the ESS's state-of-charge, the available voltage, and the available circuit breaker amp rating (current). In a best case scenario using a 240 V charger on a 90 A circuit breaker, Tesla documents a recharging rate of 56 miles (90 km)-of-range for each hour charging; a complete recharge from empty would require just under 4 hours. The slowest charging rate using a 120V outlet on a 15 A circuit breaker would add 5 miles (8.0 km)-of-range for each hour charging; a complete recharge from empty would require 48 hours

    Ouch, 40-70 amps. Our whole house has 200 amp service so around 1/4-1/3 of that is needed to service the charging needs of the car. Our electric meter already goes nuts in the summer when we run the central A/C and electric stove, I could only imagine what it would do with a char charging!

  18. #48
    Flashaholic* Wrend's Avatar
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by itguy07 View Post
    Not really...
    Yes, really, at least according to the specs I've looked over. Granted, I haven't actually tested out a physical setup.

    It's not going to be better than the most efficient normal gas cars, just more efficient than most of them.

    Basically, running an ICE at maximum efficiency to charge a Li-ion type chemistry battery which is then used to drive a car can be more efficient than using the gas directly in the car. This is because of the huge wastes of energy in cars that don't run the engines anywhere near their maximum efficiencies while electric powered vehicles can use the energy more efficiently.
    Last edited by Wrend; 02-26-2012 at 11:18 AM.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Wrend View Post
    Basically, running an ICE at maximum efficiency to charge a Li-ion type chemistry battery which is then used to drive a car can be more efficient than using the gas directly in the car. This is because of the huge wastes of energy in cars that don't run the engines anywhere near their maximum efficiencies while electric powered vehicles can use the energy more efficiently.
    The best example of this that we have is the Chhevy Volt. It runs on batteries until they are depleted (for the most part), has a gas engined tuned for recharging them, etc. And you can load it up with gas, fully charge the batteries and get around 380 miles before you need to put more gas in or plug in. IIRC it's about 37 MPG according to the EPA in gas only mode.

    Let's not forget the Volt is classified by the EPA as a compact car which includes such cars as:

    Honda Civic 28/39
    Ford Focus 28/38
    Toyota Corolla 26/34
    Hyundai Elantra 29/40

    I think I'd go for the regular car and stick with the slightly lower fuel economy.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Lets not forget the energy embedded in the battery during the course of its manufacture. How much oil, gas and coal goes into manufacturing each battery -- that needs to be figured into the mix. From the point of view of operating costs AND reducing foreign energy dependence the cost of the batteries embedded energy must be factored into the mileage figures. On vehicles requiring huge expenditures for new high tech batteries every few years these numbers would blow the conventional mileage figures out the window.

    I think we would have seen these numbers by now if they were good.
    Last edited by Sub_Umbra; 02-26-2012 at 04:13 PM.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by hellokitty[hk] View Post
    AFAIK, the 18650s are A123 LiFe chemistry.
    I wonder why they haven't used 20Ah prismatic cells (made by same A123) - that'd be just 340 (instead of 6800) cells, making managing them much easier.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Sub_Umbra View Post
    ...
    I'm just making the point that it's possible to effectively charge an electric car with gasoline, which I find kind of humorous.

    I'm not arguing the viability of electric cars and their role in world affairs.

    However, as I've said, I think their only real hindrance when it comes to viability is the currently prohibitive cost of significantly higher battery capacities.

    I also think the drilling, refining, storing, and transportation of oil and gasoline as a whole is very energy needy; so if you're comparing the whole energy use involved, "electric" still comes out ahead from what I've seen. Of course, less so if you're using gasoline to charge you're car.
    Last edited by Wrend; 02-26-2012 at 08:19 PM.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Shadowww View Post
    I wonder why they haven't used 20Ah prismatic cells (made by same A123) - that'd be just 340 (instead of 6800) cells, making managing them much easier.
    Weight and size is probably the main reason. But you would get much better cycle life...

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Wrend View Post
    I'm not arguing the viability of electric cars and their role in world affairs.

    However, as I've said, I think their only real hindrance when it comes to viability is the currently prohibitive cost of significantly higher battery capacities.

    I also think the drilling, refining, storing, and transportation of oil and gasoline as a whole is very energy needy; so if you're comparing the whole energy use involved, "electric" still comes out ahead from what I've seen. Of course, less so if you're using gasoline to charge you're car.
    I agree on both counts. Viable electric cars will use a smaller number of high capacity prismatic cells (these are available in capacities as high as 200 Ah). And mass production would bring the cost of electrics under the cost of ICE vehicles. When you think about it, an internal combustion engine with many very high tolerance parts inherently costs more to manufacture than an electric with only a few much lower tolerance moving parts (the bearings in the motors are probably the only high-precision part if you go with hub motors), all other things being equal. Low volumes are why EVs cost more than their gas powered counterparts.

    As for energy to produce fuel, some sources suggest we're rapidly approaching the point where it will take more energy to mine and process the more difficult to extract oil reserves than we will recover burning them. Same with natural gas. Some types of fracking are already energy negative. The real beauty of EVs is that you're not tied solely to fossil fuels to generate the power. They're the ultimate "flex-fuel" vehicle.

  25. #55

    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by StarHalo View Post
    I'd definitely prefer the Leaf for cold weather duty; the Tesla's rather tail-happy rear wheel drive setup is very Corvette-like, precisely not what you'd want for inclement weather. The pedestrian Nissan with its skinny tire front wheel drive is vastly preferable for snow and ice.
    The leaf is approaching something more sensible. Amusingly in a recent snowy-hill climbing benchmark, an original vw beetle from the 70s performed better than many "city-SUV" cars

  26. #56

    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by Wrend View Post
    Yes, really, at least according to the specs I've looked over. Granted, I haven't actually tested out a physical setup.

    .
    no not really, you converting mechanical energy into electricity, with loses, than you charging batts. again with loses......, but you know, my antigravity ship should work just fine, according to specks i looked over, but i haven't actually tested out a physical setup.

    try to actually build it, than see if you can actualy get even close to your magic specs, and once you actually start, you'll see so many little details that aren't even taking into accout on your specs.

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    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by alpg88 View Post
    try to actually build it, than see if you can actualy get even close to your magic specs, and once you actually start, you'll see so many little details that aren't even taking into accout on your specs.
    Consider Diesel-Electric hybrids. My limited understanding is that high-power trains use this system because it is the most efficient source of power that can be used for their engines, while allowing full torque at stall. The efficiency advantages apparently come from having a diesel generator tuned for producing power at a given rate, feeding >90% electrical efficiency motors. Is it more efficient than an equally-tuned ICE? I don't know. It has different uses, though.
    My biggest light-hog is my camera.

  28. #58

    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by AnAppleSnail View Post
    Consider Diesel-Electric hybrids. My limited understanding is that high-power trains use this system because it is the most efficient source of power that can be used for their engines, while allowing full torque at stall. The efficiency advantages apparently come from having a diesel generator tuned for producing power at a given rate, feeding >90% electrical efficiency motors. Is it more efficient than an equally-tuned ICE? I don't know. It has different uses, though.
    the only reason diesel electric locomotives use that set up is cuz of ease of controlling\power transfer, it is a lot easyer to do that, than build thousand gears transmision, you have losses at generator, they aren't linear, you have loses in engine controlers, you have loses in traction motors themselves, you also convert ac to dc traction motors are ,iirc, compaund dc motors, at start they are wired series once they start moving they are switched to parallel...(armature and field)... plus hundreds other little detailes.
    the only reason why it's build that way is that is more practical, not cuz it is more efficient.
    and you don't have battery charging circuit, that is about 60% efficient.
    and on top of that you still have diesel engine that runs generator, that is about 30% efficient.

    our new city buses are build the same way, diesel turns generator, and charges on board battery, only electric motor does the driving. but the diesel\gen isn't running at constant speed, it revs up just like regular bus does, at take off, to compencate for the load.
    i see there is planty of myths on the net regarding hybrid powertrains.
    ppl wouldn't like cars that run on coal, but many don't realize most of our grid is powered by coal, so in really the it's coal that runs your electric car.
    Last edited by alpg88; 02-27-2012 at 12:42 PM.

  29. #59
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    Default Re: Tesla cars allowing batteries to become fully discharged?

    it think Saab (?) quite some years ago did such kind of range-extender/hybrid - with a small turbine.
    Unfortunately the time was not right by then.

    Isnt that kind of engine the one offering the longest runtime with the least change to failure and least consumation?
    (its running at its perfect rpm. A turbine is very bad at changing rpm, therefore in a car it makes no sense as a primary engine)
    Its also smaller than any other kind of engine
    (and a Wankel unfortunately not in a low consumation to be a match, also no wonder as its not used on a larger scale)

    If all other things were the same or comparable, I would choose
    #1: an electric engine with a turbine
    #2: electric with ... ?
    #3: wankel
    #4: diesel

  30. #60

    Default Re: Tesla cars allowing batteries to become fully discharged?

    Quote Originally Posted by yellow View Post
    it think Saab (?) quite some years ago did such kind of range-extender/hybrid - with a small turbine.
    Unfortunately the time was not right by then.

    Isnt that kind of engine the one offering the longest runtime with the least change to failure and least consumation?
    (its running at its perfect rpm. A turbine is very bad at changing rpm, therefore in a car it makes no sense as a primary engine)
    Its also smaller than any other kind of engine
    (and a Wankel unfortunately not in a low consumation to be a match, also no wonder as its not used on a larger scale)

    If all other things were the same or comparable, I would choose
    #1: an electric engine with a turbine
    #2: electric with ... ?
    #3: wankel
    #4: diesel
    it was volvo, as you see this car never came thru, that volvo had the same set up as diesel locomotive, plus batteries. but some things don't work well when scaled down.
    you can't run turbine at constant speed with generator, i mean you can but output will also be constant (iirc at least one cruise liner has turbines driving generators, but they mostly run at the same load, and have multiple turbines), in a car you can't do that you need very little power while you idle, and a lot more when you floor it, turbines take time to start and spool up, you can shut off ice, and start as needed, but not turbine
    Last edited by alpg88; 02-27-2012 at 03:03 PM.

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