7 ms·

> What can we do to get a people's e-bike that has 30 miles of range, requires no maintenance, travels 15-20 mph, and retails around $500? I agree, we need a "

by bArray 5y ago

> What can we do to get a people's e-bike that has 30 miles of range, requires no maintenance, travels 15-20 mph, and retails around $500? I agree, we need a "people's" e-bike. Bare in mind it's not unreasonable to pick up a used human-powered bike for less than $100. It needs to be cheap, safe and serviceable. I always thought the best way forwards for such a thing is to use existing mountain bikes, use the existing gearing, brakes and chain drive and add a motor/battery/control system to this. Do away with the pedals entirely, most e-bikes are far too heavy/hard to pedal to do any kind of serious cycling. If you have no intention of pedalling the thing, weight is not so much an issue. > DC motors have fallen out of favor for "brushless DC motors." BLDC motors have a longer life, better low-end torque, and are easy to control electronically. These are a good solution, but improvements in motor technology driven by automotive R+D should trickle down. I would still opt for a DC motor. Sure they are less efficient, have less torque, etc - but they are incredibly simple to drive. I imagine it might even be possible to build a reliable mechanical based controller. > Bicycles are already absurdly efficient. E-bike battery packs are small as a result. Their small size means a less energy-dense battery might be better if it obviates the need for a more complex battery management system (BMS). If you're not doing hills and rolling resistance is not so much an issue, lead acid batteries are cheap and pack a reasonable punch. They are incredibly easy to charge and have an excellent charge cycle life time.

fuzzy2 5y ago
Lead acid batteries are heavy, they are large, they don't like heat, they don't provide as high currents, they can't take as many cycles. They are not an option here. E-Bikes are already too heavy and bulky.
- mft_ 5y ago
  Agree - the e-bike is one of the minor revolutions that was enabled/driven by the accompanying revolution in battery technology.
- bArray 5y ago
  > They are not an option here. And yet they are still the battery of choice by the automotive industry who are also weary of each of your concerns. There are very good reasons as to why cars do not have LiPos. > [..] they don't like heat, [..] In terms of thermals they far much better than LiPos (you don't need a heating/cooling system for your lead acid battery). > [..] they don't provide as high currents, [..] The starter motor in your car will sink hundreds of amps during initial turnover, something you will need just a fraction of for an e-bike. Assuming your 12V lead acid battery sags to 9V under load and you're powering a 1kW motor, you're looking at a draw of about 111A, compared to 600A+ from a start motor. Share this across multiple batteries and this also reduces sag. > [..] they can't take as many cycles. In terms of cycles, I've personally found that my car's battery takes 10 years or so to stop turning over the car or holding a decent charge. Given that lead acid batteries are significantly cheaper and can be maintained, exist all over, can be easily recycled and are about to be in massive surplus when we see mass adoption of EVs, they make a lot of sense for a cheap e-bike revolution. > [..] Lead acid batteries are heavy, they are large, [..] > E-Bikes are already too heavy and bulky. As I said, the purpose would not be to cycle the thing. A motorbike for example would be a lot more heavy, yet nobody claims they are non-rideable. Also bare in mind that we are not looking to build the carbon nano tube $100k e-bike of dreams. This is just meant to be a working horse.
CodeGlitch 5y ago
> I agree, we need a "people's" e-bike. Bare in mind it's not unreasonable to pick up a used human-powered bike for less than $100. It needs to be cheap, safe and serviceable. Absolutely. For something worth several £1000 it's just not possible to secure outside in a city. Watch this as an example: https://www.youtube.com/watch?v=FuxHYcP63DE https://www.youtube.com/watch?v=FuxHYcP63DE Until a ebike is cheap enough not to hurt if stolen, I won't be getting one (even if I love the concept).
timbit42 5y ago
Have you seen the Organic Transit ELF ( https://organictransit.com/ https://organictransit.com/ ) or the Better Bikes Pebl ( https://www.better.bike/ https://www.better.bike/ )?
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by bArray 5y ago

fuzzy2 5y ago

Lead acid batteries are heavy, they are large, they don't like heat, they don't provide as high currents, they can't take as many cycles. They are not an option here. E-Bikes are already too heavy and bulky.

mft_ 5y ago
Agree - the e-bike is one of the minor revolutions that was enabled/driven by the accompanying revolution in battery technology.
bArray 5y ago
> They are not an option here. And yet they are still the battery of choice by the automotive industry who are also weary of each of your concerns. There are very good reasons as to why cars do not have LiPos. > [..] they don't like heat, [..] In terms of thermals they far much better than LiPos (you don't need a heating/cooling system for your lead acid battery). > [..] they don't provide as high currents, [..] The starter motor in your car will sink hundreds of amps during initial turnover, something you will need just a fraction of for an e-bike. Assuming your 12V lead acid battery sags to 9V under load and you're powering a 1kW motor, you're looking at a draw of about 111A, compared to 600A+ from a start motor. Share this across multiple batteries and this also reduces sag. > [..] they can't take as many cycles. In terms of cycles, I've personally found that my car's battery takes 10 years or so to stop turning over the car or holding a decent charge. Given that lead acid batteries are significantly cheaper and can be maintained, exist all over, can be easily recycled and are about to be in massive surplus when we see mass adoption of EVs, they make a lot of sense for a cheap e-bike revolution. > [..] Lead acid batteries are heavy, they are large, [..] > E-Bikes are already too heavy and bulky. As I said, the purpose would not be to cycle the thing. A motorbike for example would be a lot more heavy, yet nobody claims they are non-rideable. Also bare in mind that we are not looking to build the carbon nano tube $100k e-bike of dreams. This is just meant to be a working horse.

CodeGlitch 5y ago

> I agree, we need a "people's" e-bike. Bare in mind it's not unreasonable to pick up a used human-powered bike for less than $100. It needs to be cheap, safe and serviceable. Absolutely. For something worth several £1000 it's just not possible to secure outside in a city. Watch this as an example: https://www.youtube.com/watch?v=FuxHYcP63DE https://www.youtube.com/watch?v=FuxHYcP63DE Until a ebike is cheap enough not to hurt if stolen, I won't be getting one (even if I love the concept).

timbit42 5y ago

Have you seen the Organic Transit ELF ( https://organictransit.com/ https://organictransit.com/ ) or the Better Bikes Pebl ( https://www.better.bike/ https://www.better.bike/ )?

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