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Right now a Tesla will overheat if you run it at top speed consistently. Electric is unmatched for instant torque, but the current battery technology makes elec

by enduser 10y ago

Right now a Tesla will overheat if you run it at top speed consistently. Electric is unmatched for instant torque, but the current battery technology makes electric unsuitable for sustained high speed. As far as practical power, electric is far more useful than gasoline for aggressive city and interstate driving (unless you have a long stretch of open pavement). The lack of transmission gives a distinct advantage in surprise-passing a gasoline sports car. The thrill of instant power cannot be overstated!

silasb 10y ago
I know they have Formula E, but I'd love to see a all-electric Tesla in Le Mans.
- ubercore 10y ago
  Le Mans would probably be the worst place to get an all electric car performing adequately. Energy density and refill times just aren't anywhere near up to the task compared to gasoline. EDIT: or diesel
  - bisby 10y ago
    What if an all electric car was equipped with a complete battery swap out mechanism. Stock up a bunch of batteries. Pop out the dead one, pop in a fresh one, begin charging the dead one to reuse in a few hours (you may need quite a few spares) This could actually REDUCE refill times (if the swap out is efficient enough). If temperatures could be controlled to allow it to run in an all out mode, this could be a competitive edge? Or would this be somehow disallowed? I imagine this would be akin to swapping out the complete fuel tank in a car instead of refueling the tank, and I have no idea about racing rules.
    - bmh_ca 10y ago
      Then you probably want an aluminium battery.
    - semi-extrinsic 10y ago
      > This could actually REDUCE refill times (if the swap out is efficient enough) Have you ever watched Formula 1 or NASCAR? They can fill 20 gallons of fuel in ~10 seconds. Do you really think a battery swap system could even come close to competing with that?
      - ubercore 10y ago
        Just did some googling, and _including_ exit and entry through pit lanes, fastest refuel is 51.3s. I think a battery swap would be reeeeeally tough to accomplish. And most cars refuel every 14 laps, and races are about 384 laps. Totals over 5000km in 24hrs. That's a lot of batteries...
        mdorazio 10y ago
        Just for comparison, your numbers come out to one refill every 52 minutes. If we assume that charging a battery takes about an hour and a half (pretty reasonable based on current charge times for an 85 kWh battery), you really only need 3 batteries total. The battery swap that Tesla originally demoed was done in 90 seconds, and that was obviously for a low-speed, consumer-friendly environment. I don't see why you couldn't do a battery swap in 60 seconds if that was an engineering priority. I still think this is a pipe dream with current battery tech for other reasons (weight, power density, overheating, etc.), but from a logistics standpoint it might actually be possible.
        ubercore 10y ago
        Can an 85kWh battery do 190km at race speeds? Le Mans records are 140mph (225km/h) avg speed and 253mph (407km/h) top speed. EDIT: thanks for noticing, added metric equivs. The difference was just in the sources I found reporting the units differently.
        darklajid 10y ago
        This is confusing: Why is the distance in km, but the speed in miles per hour?
    - NotSammyHagar 10y ago
      Tesla did this, it was operational in california, and all cars were designed with this capability. you can find the video where they demo'd this. There was little or no customer demand, because supercharging works so well on teslas that its a fine solution for most people's long trips.
  - 6stringmerc 10y ago
    You're joking about the diesel part right? Audi was dominant in the Prototype class with diesel tech for years.
    - ubercore 10y ago
      I meant that batteries couldn't compare with gasoline _or_ diesel. I decided to add it exactly because of Audi :)
ferongr 10y ago
I don't think it's an issue with the batteries but rather the heat on the power electronics.
- nickff 10y ago
  The batteries heat up terribly as well. I am not sure whether the power electronics can dissipate the heat, but they are generally easier to cool than batteries because the electronics are centralized and smaller. The problem with batteries is that their heating is proportional to the square of their current output, so when you are extracting a lot of energy from them, the batteries get very hot, and there are a lot of them.
kevin2r 10y ago
Actually, how does the tesla cools down? I have seen in pictures of the battery that they have pipes connected, does those pipes goes to a heat radiator? I'm curious now.
- bcrescimanno 10y ago
  Yes, the car has a radiator to help cool the batteries. I am a former owner who had a coolant leak due to underbody damage. Unfortunately, even Tesla service wasn't aware that their car had a radiator.
- greglindahl 10y ago
  Yeah, the front grill that's low down provides airflow for the battery cooling system. There's also an extremely loud fan for it which comes on occasionally, at high temperatures while driving or at more modest temperatures while supercharging. There's also the issue of cooling the electric motor.
- ferongr 10y ago
  In addition to the batteries, the 3-phase IGBT inverter is watercooled with the aid of a triangular waterblock (each phase corresponds to one side of the block). [1] [1] http://www.pointthepower.com/wp-content/uploads/2015/09/Screen-shot-2015-07-11-at-6.54.06-AM.png http://www.pointthepower.com/wp-content/uploads/2015/09/Scre...
  - kevin2r 10y ago
    That photo of the inverter is beautiful, as I child I was passionated about electronics, I made some projects like audio amplifier and FM transmitter, never thought we were going to have electronics in cars at this level. Now I wonder how reliable are Teslas, what are the parts that are prone to fail. Going to do a research on youtube right now :)
    - ferongr 10y ago
      In theory, properly sized and protected from motor transienst, the power electronics should last the lifetime of the car (and then some). Electric locomotives and EMUs have been using IGBTs for decades in similar arrangements with active cooling.
semi-extrinsic 10y ago
> Electric is unmatched for instant torque, but the current battery technology makes electric unsuitable for sustained high speed. Well, not really (see Formula-E). If you want a battery that can sustain high power output (high specific power, e.g. LiFePO4), you have to go to a different chemistry than what Tesla uses (high specific energy, LiNiCoAlO2). Tesla could make a Model S that went fast around a racetrack, but it would mean sacrificing range. Since the 0-60 is mainly a gimmick, it's not worth sacrifising usability for. > The lack of transmission gives a distinct advantage in surprise-passing a gasoline sports car. Not sure if the advantage is that great: in the case of a modern >250 hp gasoline sports car with the de rigueur dual-clutch semiautomatic gearbox, the person in the sports car would plant their foot and be in the engine's optimal torque band within ~0.3 seconds. So I doubt there is a disadvantage of the equivalently-powered gasoline sportscar in this situation that is not dwarfed by the noise of human reaction times.
justin66 10y ago
> Right now a Tesla will overheat if you run it at top speed consistently. Electric is unmatched for instant torque, but the current battery technology makes electric unsuitable for sustained high speed. It'd be interesting and fun to see how far you could push the current model with just some software changes and some improved cooling. People have modified air-cooled Porsches to do hill climbs, and so on, so there's certainly some existing expertise in this area. Everything that comes to mind, given the Model S's design, is pretty elaborate however.

by enduser 10y ago

silasb 10y ago

I know they have Formula E, but I'd love to see a all-electric Tesla in Le Mans.

ubercore 10y ago
Le Mans would probably be the worst place to get an all electric car performing adequately. Energy density and refill times just aren't anywhere near up to the task compared to gasoline. EDIT: or diesel
- bisby 10y ago
  What if an all electric car was equipped with a complete battery swap out mechanism. Stock up a bunch of batteries. Pop out the dead one, pop in a fresh one, begin charging the dead one to reuse in a few hours (you may need quite a few spares) This could actually REDUCE refill times (if the swap out is efficient enough). If temperatures could be controlled to allow it to run in an all out mode, this could be a competitive edge? Or would this be somehow disallowed? I imagine this would be akin to swapping out the complete fuel tank in a car instead of refueling the tank, and I have no idea about racing rules.
  - bmh_ca 10y ago
    Then you probably want an aluminium battery.
  - semi-extrinsic 10y ago
    > This could actually REDUCE refill times (if the swap out is efficient enough) Have you ever watched Formula 1 or NASCAR? They can fill 20 gallons of fuel in ~10 seconds. Do you really think a battery swap system could even come close to competing with that?
    - ubercore 10y ago
      Just did some googling, and _including_ exit and entry through pit lanes, fastest refuel is 51.3s. I think a battery swap would be reeeeeally tough to accomplish. And most cars refuel every 14 laps, and races are about 384 laps. Totals over 5000km in 24hrs. That's a lot of batteries...
      - mdorazio 10y ago
        Just for comparison, your numbers come out to one refill every 52 minutes. If we assume that charging a battery takes about an hour and a half (pretty reasonable based on current charge times for an 85 kWh battery), you really only need 3 batteries total. The battery swap that Tesla originally demoed was done in 90 seconds, and that was obviously for a low-speed, consumer-friendly environment. I don't see why you couldn't do a battery swap in 60 seconds if that was an engineering priority. I still think this is a pipe dream with current battery tech for other reasons (weight, power density, overheating, etc.), but from a logistics standpoint it might actually be possible.
        ubercore 10y ago
        Can an 85kWh battery do 190km at race speeds? Le Mans records are 140mph (225km/h) avg speed and 253mph (407km/h) top speed. EDIT: thanks for noticing, added metric equivs. The difference was just in the sources I found reporting the units differently.
        darklajid 10y ago
        This is confusing: Why is the distance in km, but the speed in miles per hour?
  - NotSammyHagar 10y ago
    Tesla did this, it was operational in california, and all cars were designed with this capability. you can find the video where they demo'd this. There was little or no customer demand, because supercharging works so well on teslas that its a fine solution for most people's long trips.
- 6stringmerc 10y ago
  You're joking about the diesel part right? Audi was dominant in the Prototype class with diesel tech for years.
  - ubercore 10y ago
    I meant that batteries couldn't compare with gasoline _or_ diesel. I decided to add it exactly because of Audi :)

ferongr 10y ago

I don't think it's an issue with the batteries but rather the heat on the power electronics.

nickff 10y ago
The batteries heat up terribly as well. I am not sure whether the power electronics can dissipate the heat, but they are generally easier to cool than batteries because the electronics are centralized and smaller. The problem with batteries is that their heating is proportional to the square of their current output, so when you are extracting a lot of energy from them, the batteries get very hot, and there are a lot of them.

kevin2r 10y ago

Actually, how does the tesla cools down? I have seen in pictures of the battery that they have pipes connected, does those pipes goes to a heat radiator? I'm curious now.

bcrescimanno 10y ago
Yes, the car has a radiator to help cool the batteries. I am a former owner who had a coolant leak due to underbody damage. Unfortunately, even Tesla service wasn't aware that their car had a radiator.
greglindahl 10y ago
Yeah, the front grill that's low down provides airflow for the battery cooling system. There's also an extremely loud fan for it which comes on occasionally, at high temperatures while driving or at more modest temperatures while supercharging. There's also the issue of cooling the electric motor.
ferongr 10y ago
In addition to the batteries, the 3-phase IGBT inverter is watercooled with the aid of a triangular waterblock (each phase corresponds to one side of the block). [1] [1] http://www.pointthepower.com/wp-content/uploads/2015/09/Screen-shot-2015-07-11-at-6.54.06-AM.png http://www.pointthepower.com/wp-content/uploads/2015/09/Scre...
- kevin2r 10y ago
  That photo of the inverter is beautiful, as I child I was passionated about electronics, I made some projects like audio amplifier and FM transmitter, never thought we were going to have electronics in cars at this level. Now I wonder how reliable are Teslas, what are the parts that are prone to fail. Going to do a research on youtube right now :)
  - ferongr 10y ago
    In theory, properly sized and protected from motor transienst, the power electronics should last the lifetime of the car (and then some). Electric locomotives and EMUs have been using IGBTs for decades in similar arrangements with active cooling.

semi-extrinsic 10y ago

> Electric is unmatched for instant torque, but the current battery technology makes electric unsuitable for sustained high speed. Well, not really (see Formula-E). If you want a battery that can sustain high power output (high specific power, e.g. LiFePO4), you have to go to a different chemistry than what Tesla uses (high specific energy, LiNiCoAlO2). Tesla could make a Model S that went fast around a racetrack, but it would mean sacrificing range. Since the 0-60 is mainly a gimmick, it's not worth sacrifising usability for. > The lack of transmission gives a distinct advantage in surprise-passing a gasoline sports car. Not sure if the advantage is that great: in the case of a modern >250 hp gasoline sports car with the de rigueur dual-clutch semiautomatic gearbox, the person in the sports car would plant their foot and be in the engine's optimal torque band within ~0.3 seconds. So I doubt there is a disadvantage of the equivalently-powered gasoline sportscar in this situation that is not dwarfed by the noise of human reaction times.

justin66 10y ago

> Right now a Tesla will overheat if you run it at top speed consistently. Electric is unmatched for instant torque, but the current battery technology makes electric unsuitable for sustained high speed. It'd be interesting and fun to see how far you could push the current model with just some software changes and some improved cooling. People have modified air-cooled Porsches to do hill climbs, and so on, so there's certainly some existing expertise in this area. Everything that comes to mind, given the Model S's design, is pretty elaborate however.