It sounds bizarre but I want to try it.

  • Voyajer@lemmy.world
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    9 months ago

    You won’t gain anything meaningful from an overdrive with electric motors, they don’t need to be kept in a small rpm band to not lose efficiency

    • BallShapedMan@lemmy.worldM
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      9 months ago

      Overdrive puts the engine in a lower RPM band which would save the battery I feel like. Plus a few cars have em.

      • sparky1337@ttrpg.network
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        9 months ago

        Electric motors don’t like low rpm’s. You’ll end up using more battery as the torque requirement to move the taller gear set is higher.

        • BallShapedMan@lemmy.worldM
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          9 months ago

          So a small high RPM motor that doesn’t have a lot of torque and needs higher gear ratios to make up for it but uses less electricity in trade is out?

          Seems silly to me.

          • sparky1337@ttrpg.network
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            9 months ago

            So it’s just how electricity works. With an ICE engine you have a powerband, and the individual gears solve the issue of power and efficiency.

            CVTs also solve this issue by putting the ICE motor at peak rpm efficiency for the task. Eventually with an ICE motor the rpm’s can only go so low or else you’ll lug the motor introducing extra heat and pressure that will blow it up.

            Back to electric, what happens when you turn a switch on in a room to power a light or fan? Why are fan settings 0-3-2-1 and not 0-1-2-3?

            It’s because motors are designed to come on at full power to overcome mass. If you were to introduce a taller gear set like an ICE motor, even at higher speed, you’re introducing the motor to higher resistance than the voltage can overcome so it puts extra stress on the electric motor which in turn increases the amperage.

            This will consume more power, and create excess heat, thus lowering efficiency. Not to mention the vehicle has to overcome drag and air resistance and the extra weight of this new drivetrain on an already heavy vehicle.

            Now, that’s not to say it isn’t impossible or impractical, but there’s no real efficiency to be gained since electric motors maintain same or similar efficiency across all ranges.

            • BallShapedMan@lemmy.worldM
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              9 months ago

              That all makes sense except why do some EVs have real gears? I feel like Porsche probably knows what they’re doing when they put one in theirs.

              • sparky1337@ttrpg.network
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                9 months ago

                Theirs unfortunately has no efficiency benefit. There’s two motors in the taycan, front and back.

                Front motor is single speed, and once the car hits 62mph it shifts to second in the rear motor only.

                The taycan is all about being fast, not efficient.

                • BallShapedMan@lemmy.worldM
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                  9 months ago

                  Maybe that’s the use for a transmission then? Like CPU cores, efficiency cores and performance cores? Dunno, not an expert here. I do think what we think now is unlikely to be what we think as the technology matures and gets reinvented.

                  • sparky1337@ttrpg.network
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                    9 months ago

                    Yes, in reviews and media documents it is mentioned the Taycan has the second gear to be able to maintain Autobahn level speeds. It’s not explicitly mentioned, but Porsche won’t outright confirm efficiency last I looked, so even they don’t think it helps range. Just speed.

                    But it’s not that there isn’t efficiency to be gained, it’s just so small it’s not worth it. In order for even a 2 speed ev, the shift point would need to be approximately 70-80mph to realize efficiency gains.

                    That’s just not something that’s done with EV’s. Most are city centric, and even if you are driving 70-80mph in an EV, you’re hitting peak efficiency of the motor anyways. It’s a bell curve, so it’ll only start to taper off not drop like a cliff. Although, the one side might drop faster due to how resistance works.