Why Tesla wanna go Hybrid when is already 100% electric?

gwmortgwmort Member Posts: 22
edited April 2014 in Tesla
To increase range


  • coldcrankercoldcranker Member Posts: 877
    To reduce the price of a Tesla, since batteries are so expensive. Less batteries with an added engine lowers the price, opening up markets, making it more affordable to more people. Cost, cost, cost. And the range does go up, too.
  • wwestwwest Member Posts: 10,706
    An internal compustion could, COULD, be designed/built that would be more efficient than charging off the grid. Note that NO ONE has taken the position that power from the grid is all that efficient insofar as FE and emissions are concerned.

    Everyone seems to be focussed solely on the current low cost of each Kilowatt hour from the PLUG....Subject to change with NO notice.

    Build a smallish CNG fueled SuperChargered engine, Miller Cycle engine, that ALWAYS operates at its most optimal speed, at or near WOT(minimized pumping losses), and I have no doubt that one could OUTPERFORM the commercial grid's power generation, distribution losses/costs and adverse environmental effects.
  • toyolla2toyolla2 Member Posts: 158
    I would say that anyone who has taken a College or University course in thermodynamics is likely to become an enthusiast towards residential and even small business cogen installations. With only a 6kw generator running on natural gas the release of 18kw in low grade heat (at full load ) is available from the radiator coolant for space heating. Had you been using an open flame forced air natural gas system before, this changeover can make your electricity bill just disappear. While we continue to use fossil fuels in the medium term a cogen system like this offers much better payback than the "boutique" energy systems of wind and photovoltaics. Of course, it won't be all plain sailing since the established central electricity generating boards aren't going to be taking lightly this threat to their status quo.

    Back on topic, however, it would be a good idea for Tesla to be looking at batteryfree series hybrids so that they can leverage their electronic powertrain technology towards other applications that don't include long strings of Li-ion just in case they get locked out of the large format battery Li-ion business upstream.

    I am sure there are motorcycle engine manufacturers around with the knowhow to develop 100Hp for a highspeed genset application using a lot less parts than currently available 4 cyl automobile engines employ. Modern automobile engines still carry a lot of baggage to cope with the clutch coupled multi-ratio transmission that, save for the Prius, is used exclusively today.
  • wwestwwest Member Posts: 10,706
    "..motorcycle engine manufacturers around with the knowhow...."


    The "HOG" cycles use engine technology from the 1930's and that's the way the owners like/want it. On the other end of this spectrum is 'cycle engines that run at 12-18,000 RPM.

    So it's the aircraft engine manufacturing company's that are more likely to have the expertise for this, CONSTANT RPM, HIGH output power at relatively LOW RPM, for hour upon hour and decent FE to boot.

    What is needed for road-going engines, at the "BASE", really amounts to TWO engines, a small displacement but HIGHLY efficient ICE for simply cruising, and a HUGE ICE (battery in the current crop of 0-60 oriented hybrids) to yield the acceleration levels that US owners seem to value so highly.

    The obvious answer to that conundrum is a hybrid, total battery road power but with a small high efficient, probably constant speed, fossil fuel (CNG) engine/generator with the ability to supply just enough electricity to allow the electric drive motor(s) to move the vehicle along at reasonable road speeds and simultaneously recharge the battery in order to keep a RESERVE charge available for use as a SuperCharger.

    Looks to me like Tesla may be on to something.
  • coldcrankercoldcranker Member Posts: 877
    wwest, You are describing the Volt, due out in about 1.5 years. It will transfer power from the engine+gen straight to the electric motor, with excess being routed to the batteries to keep them at minimal charge. The batteries can then act in bursts when needed to fill in high-torque temporary demands. The engine can then operate at or near its optimal sweet-spot RPM. Also, remember the primary factor in engine efficiency is compression ratio, the higher the better, and if you only run the engine in a narrow RPM range, you can also get a higher compression and optimize your direct injection to run withouth knock.

    One thing people often forget is that when you charge a battery, you lose about half the energy to heat, analagous to spilling juice on the floor sloppily.
  • toyolla2toyolla2 Member Posts: 158
    - wwest,

    the 2009 Honda CRF450R motorcycle sports a single cylinder 449cc capable of 56Hp @ 8500rpm. The whole bike weighs 200+ lbs.
    The engine by itself sans gearbox/clutch probably weighs around 40lbs. This happens to be exactly twice as powerful as the Prius battery, which Gagrice reckons to weigh in at about 90lbs.

    The underlying point is to say that for mobile applications
    the best storage for energy is in petroleum rather than a battery. And the best method to extract that energy from petroleum is with a reciprocating engine.
    And the best way to manipulate the ensuing power is to convert it into electricity.
    And the best manipulator is the electronic inverter which can effectively swap volts for amps needed for low speeds and later on swap amps for volts when accelerating at high speeds with a pre-stage upconverter (like Gen II Prius) thus effectively providing an electric analog of a mechanical gearbox action.
    Finally the most robust and least inexpensive transducer to turn that electric analog into a mechanical analog is the induction motor.

    These last two points are, of course, covered by Tesla.
    As I see it the aim of Tesla is to produce that 4 second to 60 rush without the unreliabilty and NVH of V12 engines.

    But would a pair of these motorcycle engines accomplish this task ?
    I am not saying that, but just consider.......

    The pre- production EV1 acheived 60mph in 8 seconds with just 114Hp and 1175lbs of lead acid battery. If the weight delta by dispensing with these was factored in, an overall saving of 1000lbs might result.

    This could yield a figure of six seconds to 60. As I recall, the EV1 didn't reach full power until 42mph. The superior ampacity of Tesla's inverter could lower that point to 20mph and further improve on this figure.

    Obviously I am not interested in pure electric cars, only the technology they present in moving us away from the use of large mechanical engineering systems of current vehicles. Need I say more ?
  • wwestwwest Member Posts: 10,706
    56HP @ 8500RPM....

    The best way to make us of that "power" is to provide a "power" accumulator so that when the engine runs it runs ONLY at the most optimum RPM. In the Tesla that accumulator is called a "battery".
  • toyolla2toyolla2 Member Posts: 158
    Respectfully but your mind is locked up with this obsession for efficiency as a primary need for a powertrain.

    Having looked at this for quite a few years, my mind changed from efficiency towards an obsession for efficacy instead.

    Since acceleration is such a small part of the driving cycle - it lasts only a few seconds - we don't have to be concerned with peak efficiency at that time. It's what comes afterwards that concerns me.

    Case in point. Consider If I accelerate to 60mph in eight seconds and then drive a further three miles at that speed. But no accumulator battery is used at all, only a direct gasoline-electric powertrain.

    Then what you are saying is this,
    that what happens during those first 117yds is going to significantly affect my overall fuel economy for the whole three mile trip
    you are saying that what happens in 1/16mile will affect the next three miles. Put another way the first 2% of the trip will significantly ruin any fuel economy I might gain with that small engine over the whole trip !! Quite frankly, I don't see it.

    To go with your idea instead, I would assume, is to suggest the additional installation of a couple of Prius battery systems (weighing 180lbs total and costing $5000 total plus significant bulk)) to supply 50Hp during acceleration in order that I can limit my engine to run at its peak thermal efficiency which may occur at around only 15Hp ?

    Oh and by the way, let's conveniently forget that there is a continuous tire rolling resistance loss of humping that 180lbs of "boutique energy storage" around the streets at 60mph of at least 115watts !!

    -wwest I have limited time to hammer my points home so it'll be interesting to see how much of this post you will ignore.
  • wwestwwest Member Posts: 10,706
    The thing to do, theoretically, is figure out the average power requirement and provide a fossil fuel engine that running at its most optimal RPM provides 30% greater power.

    The add a battery ("accumulator") to fulfill the need for power surges above the average.

    Permanent magnet rotor AC synchronous electric motor/generators provide EXCELLENT capability in this regard.

    The ICE only runs if the battery SOC gets low enough....

    The way I see it the "fly" in your "ointment" is that US drivers have grown used to upwards of 200HP for acceleration when all that is needed for simply cruising along at a constant speed might be as little as 25-30HP. That's HUGE operational range for a fossil fuel engine to be made efficient across.

    Spoiled, we are.

    Maybe a 40,000 PSI hydraulic pump/accumulator and a few gallons of ATF.
  • coldcrankercoldcranker Member Posts: 877
    wwest said: "Maybe a 40,000 PSI hydraulic pump/accumulator and a few gallons of ATF. "

    wwest is right. See Hydraulic Hybrid Truck saves 50% fuel in stop-n-go UPS delivery style driving!!!! -- click here.... And for the comment about using ATF fluid, I know for a fact that there is a wonderful biodegradable hydraulic fluid on the market now, so there is no problem there, either.

    Actually, I think they run the accumulator at 3,000 PSI. Works great on trucks in city driving cycles. How does 50% fuel savings for those massive fleets of UPS, Fedex, garbage trucks, local mail trucks, etc. sound to you? Obama should be putting TARP money and/or econ stimulus money into that to sock-it-to the mideast and Chavez (Citgo)! And who in this economy doesn't use Fedex, UPS, garbage trucks, and/or the Post Office on a regular basis? It would benefit every working man out there and stim the econ, too. Those big-[non-permissible content removed] trucks suck diesel like its going out of style. And the pollution it would cut? Another benefit. (Vote for me after Obama is done, and I'll fix stuff.)

    Tesla would have a hard time using hydrualic accumlators because of the space limitations on a sports car chassis, although if they come out with a sedan and devote half the trunk space to it, then we got something......

    I'm with the group that hates batteries. They are too heavy and expensive. None of which appeals to the engineer in me (performance) and economist in me. Still, I know electric hybrids can work very well for many applications, of course.

    Tesla could cut down the cost of their laptop-computer-battery monstrosity if they cut the amount of batteries in half and put a sweet little low-friction internal combustion gas engine in there. Remember, freight trains have been using a series hybrid arrangement (no transmission) for many years, and that is essentially like an 80% efficient transmission, not great, but acceptable, and I don't even think a freight train stores much of its excess energy in what very minimal batteries (lead-acid) they have on board.
  • toyolla2toyolla2 Member Posts: 158
    -wwest, I do understand your strategy. Many other posters here and elsewhere suscribe to the same strategy, I admit.

    They all start with what is a basic BEV and then add what Coldcranker just described as a sweet little low-friction internal combustion gas engine.
    This does indeed reduce the need for substantial onboard storage of electrical energy. The problem is we can't do that with the Tesla.

    We can't just remove half of the Tesla's battery since that would cut the Power Capability of 220 Kw in half as well.

    Obviously that would compromise performance. A situation that it won't be possible to redress even with help from that small gas engine which I assume to be designed with technology significantly beyond that permitted in a lawn mower engine in terms of emissions and fuel efficiency. Consequently the engine has to be added to the Tesla on top of what is already there and won't be displacing any battery.

    That aside, what seems to be missing from this range extender strategy is that the infrastructure to support such an internal combustion engine is not minor. Considerations for air intake and exhaust, pressurised fuel storage for the fuel injection system, and provision for a cooling radiator will still exist. The costing for these parts won't be significantly below that of a conventional automobile engine. Manufacturing costs just do not scale down very well - as much as we would like them too.

    That being the case one might as well select an engine with increased bore diameter and operate it at increased piston speeds for a lot more power as per the previously described Honda engine with its optimized cylinder head cooling and oil jet-cooled pistons. Then there is still the option to go even further with the use of a titanium con rod and sodium filled valves, With such an engine we can start extracting some real power and dispense with a storage battery entirely.

    For the Tesla I would think that at least two of these engines would be required but they could share the infrastructure.
    Since there are no mechanical couplings, when cruising only one engine need be operational at a time.

    This is all known technology and does not rely on the longterm properties of Li-ion battery arrays nor hydraulic/accumulators running at potentially dangerous pressures.

    The Tesla model swaps 600lbs of engine technology with 600lbs of boutique priced power to provide off the line performance second to none, additionally getting 'off oil' - perceived by some as a bonus.
    Only experienced drivers in Ferraris and Lambos will give this vehicle any competition at all. With superlative throttle response, on the track, this vehicle will come out of the turns faster than any gas powered vehicle. On that account I can see it having its own racing series.

    However I believe all this is due to the electric drive and not specifically due to the Li-ion power source. When it comes to power to mass I am convinced that the reduced mass of the series hybrid approach is also viable and although it may not be completely off-oil as others would want, it certainly will be an off-a-helluva-lot-of-oil design.
  • wwestwwest Member Posts: 10,706
    Back when I had my name on a list for an early purchase of an RXh I was considering this issue, but in a different aspect. Removed my name when it became obvious teh RXh was aimed at "boy-racer", 0-60MPH, type personalities.

    My thought was to buy a "tag-a-long" one wheel trailer on which would be mounted a 12-16KW (18-24HP) solid state inverter CNG genset used to continuously "charge" the hybrid battery. The idea would be to size the genset so it would run mostly at 80% throttle during constant speed highway cruising and only go WOT for "make-up".
  • coldcrankercoldcranker Member Posts: 877
    wwest, The only thing wrong with having an internal combustion engine to do nothing but charge the batteries is that energy produced by the engine itself is only about 30% efficient, and then the act of charging batteries is about 50% efficient, so you are left with 15% overall efficiency, very low. It is why the Chevy Volt engineers decided NOT to try and charge the batteries on board up very much (only enough to keep them at minimum charge). The Chevy Volt pretty much works like a diesel-electric freight train (very common for years) where the internal combustion engine simply turns a generator and the current from that flow mostly directly to the electric motor to turn the wheels. The battery only gets leftover power enough to maintain a minimal state of charge.
  • toyolla2toyolla2 Member Posts: 158
    look we are getting a bit off topic here with mechanical systems and the Volt There are the Advanced hybrids forum for normal cars and also the Volt forum, we should continue on those.
    The Tesla is on its own as a hybrid application due to the power required. It will definitely require a multicylinder engine if it is to run on oil, although for our personal transportation needs I feel that is exactly the type of engine that we should all be trying to get away from .
  • coldcrankercoldcranker Member Posts: 877
    Thanks for the link. TESLA SHOULD DO THAT!
    Hydraulic hybrids kick butt, man. Big trucks and whatever can benefit.
    If Tesla did this hybrid arrangement (forget battery crap!), they would have a rocket ship off the line. People should understand that hydraulic hybrid TORQUE is incredible, very high. Thats why Tesla, wanting to give us a satisfying sports car, should give us this accleeration kick.

    That answers the purpose of this thread exactly. Thats why Tesla would want to "go hybrid".
  • wwestwwest Member Posts: 10,706
    Very few of us in "this" market are looking to take off like a rocket ship.
  • coldcrankercoldcranker Member Posts: 877
    wwest said "Very few of us in "this" market are looking to take off like a rocket ship."

    Huh? This is a Tesla thread. You didn't know that a lot of the appeal of buying a Tesla is the amazing acceleration you are getting in a sports car? I think its something like 4 seconds 0 to 60 mph. Thats HUGE in this market. This ain't no Prius thread. The snail-lovers are over there. Prius takes 11 seconds to get to 60.

    Any Tesla-going-to-hybrid has to keep that Tesla-wild acceleration intact, at least most of it.

    When people pay their $100,000+ for a Tesla roadster, at least they get neck-snapping accleration, and Tesla is proud of that.
  • coldcrankercoldcranker Member Posts: 877
    Here is another reason Tesla should go hybrid (the subject of this thread):
    Click Here for what Tesla should be building in a hybrid, as it gets Tesla-like accel for cheaper
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