• Drewmeister@lemmy.world
    link
    fedilink
    arrow-up
    17
    ·
    2 days ago

    It would wash out. Any energy collected would be at the cost of resistance. So add fans to add wind resistance. You could collect energy from coasting and braking, but that’s just tech we’ve been using for years in cars, and it comes at the cost of movement. It actively slows you down because the energy has to come from somewhere. And since energy conversion is hardly one-to-one (loss to heat, etc), storing it into a battery and then pulling it out again means you won’t gain as much as you lose.

    Energy cannot be created or destroyed. If you are generating energy, you’re taking it from somewhere, and on a bike, it’s from your forward movement.

    • pelespirit@sh.itjust.works
      link
      fedilink
      arrow-up
      5
      arrow-down
      2
      ·
      2 days ago

      Okay, I get that, but wouldn’t the collection be a separate system? The energy is being created by the battery, then a separate system collects the energy.

          • Drewmeister@lemmy.world
            link
            fedilink
            arrow-up
            10
            ·
            2 days ago

            Yes, you could collect energy while coasting down a hill, but it would slow you down. Which is fine if you want to slow down; this is the basis for regenerative braking. You might be thinking that a pinwheel spins like crazy in the wind, and that’s just free energy. But a pinwheel doesn’t store anything. To store energy, you need to add resistance, and the more you add, the more energy you collect and the harder it is to spin the wheel.

            So at the end of the day, you’ve got a fan at the front of the bike that is either spinning quickly with little resistance and storing little energy or one that is spinning slowly and collecting more. And the slower it spins, the more pushback there is against your forward movement.

            Despite there being two batteries, this is still a single system which uses energy to propel the bike forward and collects energy by preventing the bike from moving forward. They offset. The only way to have the energy to propel the bike is by introducing energy from another source (not related to the movement of the bike) such as a battery charged ahead of time or calorie loss of the rider (active pedaling).

          • Ekky@sopuli.xyz
            link
            fedilink
            English
            arrow-up
            5
            ·
            edit-2
            2 days ago

            Now you’re introducing potential energy (a hill), which will be used up (or rather be fully converted to kinetic energy) once you reach the bottom, and you’re going to need the same or more energy to go up that same hill again (depending if you take resistance into account).

            We already have tech for capturing kinetic energy for later in the same battery used for driving called “Regenerative braking” (cuz’ the motor is used as a generator in place of brakes, and you’ll need to drive said generator by capturing/braking some of your kinetic energy/forward motion).

            EDIT: In other words: You could just start on a really high hill and you’d be able to use the weight of the bike and yourself as a “battery”, never needing any actual battery/motors/wiring/etc.

      • Imagine it like this, you have two glasses of water, labeled “speed” and “chemical.” You can only transfer water between glasses. And messily. It’s a sum of water, a specific weight of water between the two glasses that you own. In placing the water elsewhere, you haven’t done much besides lose a portion in the transfer. You can absolutely do what you’ve said! It will, unfortunately, just be a transfer from the speed to the chemical glass. You’d just lose a bit in the transfer.