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Free energy mod! (europe.pub)
submitted 1 year ago by to c/linkedinlunatics@sh.itjust.works
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[–] 8 points 1 year ago* (13 children)

But do e-bikes have regenerative braking? I haven't seen that. I've been thinking that it would just be too heavy and clunky to be worth it.

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  • [–] 26 points 1 year ago (8 children)

    Too heavy? You just run the motor in reverse which turns it into a generator and adds friction to do generative braking. There really isn't any added weight.

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  • [–] 15 points 1 year ago (3 children)

    Bikes normally have freehubs, a ratchet on the cassette (sprockets) of the rear wheel, when you stop pedalling the bike freewheels, without that the pedals would keep turning.

    This makes driving a motor from the wheel impossible without heavily modifying the normal bike mechanics. That's why regenerative braking on e bikes is rare.

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  • [–] 10 points 1 year ago (2 children)

    Not if you have a hub motor. Those don't interact with the gear system at all.

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  • [–] 2 points 1 year ago

    Only very cheap e-bikes have hub motors. They're not a good idea precisely because they don't interact with the gearing system. So you lose that functionality.

    It's not worth losing access to gearing just to get regenerative braking because the amount of power being used isn't worth trying to recoup.

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  • [–] 6 points 1 year ago (3 children)

    It needs a direct drive which is more weight than the other systems

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  • [–] 5 points 1 year ago (2 children)

    Why would it need a direct drive? A mid drive can do the same thing they just don't usually since you'd need to gear for it. direct drives are the most efficient at regenerative braking but they aren't the only type.

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  • [–] 1 point 1 year ago* (last edited 1 year ago)

    Could be done, perhaps, with significant added complexity (and hence maintenance). In practice it is not, to my knowledge there are no mid-mount regenerative system on the market. It is worth noting that mid-mounts are significantly more efficient than hub mount, enough so that even compared to hub mounts with regeneration, mid-mounts have more range for a given battery / wattage. The vast majority of hub mounts also do not implement regeneration.

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  • [–] 6 points 1 year ago* (1 child)

    Motors are generators when run inversely:

    Motors = put in power to get rotational movement

    Generators = put in rotational movement to get power

    You already have the heaviest parts on the ebike - motor and battery, just need some capacitors and charging circuit board which are light and not too big.

    Cheap electric bikes I've ridden with regen breaking slow you down quite a bit.

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  • [–] 2 points 1 year ago

    It's not difficult to get regenerative braking on a bike it's just difficult to get regenerative braking on a bike that's any good. Hub mounted motors are the least efficient type of motor because it's just directly driving the wheel at whatever speed it can output, with no access to gear ratios. E-bikes that forgo generative breaking in favour of a more efficient motor designs achieve better speeds for any given amount of power usage.

    So yeah you can absolutely do it. But it's not a good idea for reasons that have nothing to do with the weight.

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