quote: REALLY? So the fact that electric motors' torque declines sharply as RPM increases is better than a gas engine, whose torque curve remains relatively flat as RPM increases, only to decrease gradually near the redline.
quote: Actually no. During the current limiting phase of the electric motor acceleration (zero RPM to peak power) the electric motor will produce pretty much constant torque due to constant current. When the motor reaches peak power it goes into the voltage limited phase where the back EMF of the motor limits the current and available torque goes into gradual decline.
quote: Current limits and battery voltage are not set in stone but are chosen by design for reasons like extending battery life.
quote: ICE's have zero torque available at zero RPM and therefore must idle. To get a car moving some slippage has to occur either by clutch or torque converter. An ICE's torque curve is far from flat anywhere in the RPM range.
quote: Back EMF does not limit current, it represents an increase in voltage that will rise until it matches the input voltage.
quote: With the Tesla, you could easily find yourself out of batteries after doing a few 0-60 sprints "for fun" at full throttle.
quote: Torque converter are viscous couplings and do not "slip".
quote: I don't know if it was true that he was just quoting wikipedia, but back EMF does indirectly limit current. You are correct about the current limit due to wire heating, but that's at low RPM. At higher RPM, there's a power limit due to battery/electronics/cooling, so V*I*pf is roughly constant, and voltage goes up while current (and torque) goes down with RPM. At even higher RPM, you hit a voltage limit from wire insulation and/or IGBT limits. So now you can't keep V*I constant, and ever increasing back-EMF with RPM limits current even faster.
quote: If by "a few" you mean "hundreds", then sure.0-114mph sprint, and cruising back to zero. 1 mile travelled, 0.5kWh used. So even with a leadfoot, you can cover 150+ miles on a charge.
quote: "Slip" is defined as the difference in rotation speed between input and output. Yes, viscous couplings have non-zero slip.
quote: You say no, and then basically say what I just said followed by something you paraphrased from wikipedia in an attempt to seem smart but likely don't understand.
quote: Voltage determines the speed of the engine; the current drawn will rise if a load is placed on the motor (which causes a drop in voltage). Current itself is limited by system wiring and the motor's windings, and exceeding this current would cause the motor and/or wiring to overheat.Will be funny to see what happens if a Tesla motor stalls while stuck at "full throttle". It will basically weld itself into a clump of molten metal in seconds.
quote: I'm not paraphrasing anybody!! Because your statement implieded that torque drops off (sharply) from zero RPM I stand by my disagreement with that.
quote: You might know the electrical theory but you don’t know how EV’s work. The motor controller will limit the current available to the motor. At low motor RPM it will chop the voltage to ensure that the current doesn’t exceed its preset limit. This is what I call the current limited phase. As the current available is the preset limit it is constant as is available torque. It’s the motor controller that limits the current not the load. Of course that is semantics as the load will increase to match the current i.e. the car will accelerate there by loading up the motor. As the motor crosses peak power (maximum voltage, maximum current) the back EMF generated by the motor is sufficient to prevent the current from exceeding the preset limit of the controller.
quote: The point is that electric motors' having full torque from 0 RPM is not an advantage over the gas engine. Sure, it makes the car "feel" fast but the performance figures tell the full story, and they're not exactly shattering any records.
quote: Current itself is not what drives the motor, it is VOLTAGE that makes things move. Voltage must be high enough to overcome the resistance of the system, and when a load is placed on the motor, resistance increases and voltage drops. To maintain a speed at a given voltage, more current is drawn by the motor.