Scientific_potato Posted May 24 Share Posted May 24 This is probably nothing more than a cool science fair experiment/project but i had an idea: Motor | Pedals/Alternator -> Computer <-> Battery <-Regen brakes I searched it up and even the best alternators are only about 80% efficient. Any ideas on how i might improve on this design? Link to comment Share on other sites More sharing options...
exchemist Posted May 24 Share Posted May 24 20 minutes ago, Scientific_potato said: This is probably nothing more than a cool science fair experiment/project but i had an idea: Motor | Pedals/Alternator -> Computer <-> Battery <-Regen brakes I searched it up and even the best alternators are only about 80% efficient. Any ideas on how i might improve on this design? You’ve left out the wheels. Link to comment Share on other sites More sharing options...
Scientific_potato Posted May 24 Author Share Posted May 24 Just now, exchemist said: You’ve left out the wheels. Well yea, but it should be obvious that its part of it right? Link to comment Share on other sites More sharing options...
exchemist Posted May 24 Share Posted May 24 (edited) 17 minutes ago, Scientific_potato said: Well yea, but it should be obvious that its part of it right? At present you show 2 sources of mechanical power ( motor and pedals) and 2 sources of electricity( regen brakes - which by the way implies another generator and/or motor which is not mentioned - and a battery) connected, not to the wheels, but to a computer. That makes no sense unless you want to fry its circuits. So far you are not describing a design or even a concept. Where is the motor? Is it in the hub of a wheel to drive it directly, or somewhere else? If the latter how is it connected to the powered wheel? Is the generator that provides the regen braking the same motor, or a different machine? And so on. Edited May 24 by exchemist Link to comment Share on other sites More sharing options...
Scientific_potato Posted May 24 Author Share Posted May 24 3 minutes ago, exchemist said: At present you show 2 sources of mechanical power ( motor and pedals) and 2 sources of electricity( regen brakes - which by the way implies another generator and/or motor which is not mentioned - and a battery) connected, not to the wheels, but to a computer. That makes no sense unless you want to fry its circuits. So far you are not describing a design or even a concept. The computer is there to regulate/direct the electricity Link to comment Share on other sites More sharing options...
exchemist Posted May 24 Share Posted May 24 Just now, Scientific_potato said: The computer is there to regulate/direct the electricity No shit! How? Link to comment Share on other sites More sharing options...
Scientific_potato Posted May 24 Author Share Posted May 24 1 minute ago, exchemist said: No shit! How? I honestly thought that if you had a computer specialized to do that you could just do it, or just connect it to a relay? Link to comment Share on other sites More sharing options...
exchemist Posted May 24 Share Posted May 24 Just now, Scientific_potato said: I honestly thought that if you had a computer specialized to do that you could just do it, or just connect it to a relay? Look, I’m sorry to seem harsh, but all you have done is propose a motor, a battery, pedals and some kind of unspecified regenerative braking, controlled, in some undefined way, by a computer. Do you really think saying just that is enough to constitute a design? Link to comment Share on other sites More sharing options...
Scientific_potato Posted May 24 Author Share Posted May 24 Just now, exchemist said: Look, I’m sorry to seem harsh, but all you have done is propose a motor, a battery, pedals and some kind of unspecified regenerative braking, controlled, in some undefined way, by a computer. Do you really think saying just that is enough to constitute a design? You're right, my apologies i'd just like to mention that i have not gone to college or anything like that, its really just my hobby to learn things from discussions online. Link to comment Share on other sites More sharing options...
exchemist Posted May 24 Share Posted May 24 2 minutes ago, Scientific_potato said: You're right, my apologies i'd just like to mention that i have not gone to college or anything like that, its really just my hobby to learn things from discussions online. OK, then let’s pursue this a bit. Where is the motor, and will it also function as a regenerative brake? Just looked on line and some bikes have regenerative braking: https://intermountainbikes.com/which-electric-bikes-have-regenerative-braking/ Link to comment Share on other sites More sharing options...
Scientific_potato Posted May 24 Author Share Posted May 24 7 minutes ago, exchemist said: OK, then let’s pursue this a bit. Where is the motor, and will it also function as a regenerative brake? Just looked on line and some bikes have regenerative braking: https://intermountainbikes.com/which-electric-bikes-have-regenerative-braking/ The motor is connected to the rear wheel Just to be clear, do you know those flashlights you can charge by cranking? the thing inside of that will be connected to the pedals. Link to comment Share on other sites More sharing options...
exchemist Posted May 24 Share Posted May 24 2 hours ago, Scientific_potato said: The motor is connected to the rear wheel Just to be clear, do you know those flashlights you can charge by cranking? the thing inside of that will be connected to the pedals. OK so in your design there won’t be a chain between the pedals and the wheels, i.e. the whole transmission would be electric? That may be new. Link to comment Share on other sites More sharing options...
pzkpfw Posted May 24 Share Posted May 24 These things exist. Link to comment Share on other sites More sharing options...
exchemist Posted May 25 Share Posted May 25 11 hours ago, pzkpfw said: These things exist. Interesting. However I’d have thought, based on what I understand of diesel-electric traction, that this would incur significantly higher losses than a mechanical, i.e. chain or belt, drive. Perhaps with a battery, i.e. as a rechargeable hybrid, this could be overcome, but at the cost of needing to charge the battery periodically from an external source. I don’t think I’m persuaded that this would be a great idea, though I must admit getting rid of the chain, with all its attendant problems, might be attractive. Link to comment Share on other sites More sharing options...
pzkpfw Posted May 25 Share Posted May 25 Once you stick a battery in, then regenerative braking starts having value, so no more of your energy goes to making brake pads get hot. Maybe then it's seen more as a battery driven bike, where your pedaling is a range extender? I like the idea that (at the cost of more weight) this would make it possible to stick another motor in the front wheel - a 2 wheel drive bike? Maybe good in mud? I don't have the skills to calculate which is best. Link to comment Share on other sites More sharing options...
J.C.MacSwell Posted May 28 Share Posted May 28 Though less efficient than direct drive the rider can pedal more efficiently. For example, on down hills with excess speed not only can regenerative braking be used but the rider can continue pedaling at average power output...uphill can be done at better speed than the rider could otherwise do while the rider continues pedaling, again at average/optimum output. Don't forget to exchange batteries now and then with your super fit friend while you enjoy pedalling in each others company while both exercising optimally. Link to comment Share on other sites More sharing options...
pzkpfw Posted May 28 Share Posted May 28 Nice points. Probably also means on a tandem bike, both people can pedal to their ability, and are not locked by a chain into needing the same RPM. Link to comment Share on other sites More sharing options...
exchemist Posted May 28 Share Posted May 28 5 hours ago, J.C.MacSwell said: Though less efficient than direct drive the rider can pedal more efficiently. For example, on down hills with excess speed not only can regenerative braking be used but the rider can continue pedaling at average power output...uphill can be done at better speed than the rider could otherwise do while the rider continues pedaling, again at average/optimum output. Don't forget to exchange batteries now and then with your super fit friend while you enjoy pedalling in each others company while both exercising optimally. All valid points, but you will still expend considerably more energy (perhaps 30-40% more) on this machine to get from A to B than on a conventional bike, due to the combined transmission losses and the extra weight of motors, generator and battery. Link to comment Share on other sites More sharing options...
J.C.MacSwell Posted May 28 Share Posted May 28 2 hours ago, exchemist said: All valid points, but you will still expend considerably more energy (perhaps 30-40% more) on this machine to get from A to B than on a conventional bike, due to the combined transmission losses and the extra weight of motors, generator and battery. The weight might only increase 5% range when considering the rider and any cargo and not just the bike. Comparable to existing ebikes. Transmission losses would be mostly one way, maybe a few extra percent. That leaves generation and regeneration losses, and charging, discharging and recharging losses (anything else?) vs regeneration recovery and more efficient pedalling overall. I Link to comment Share on other sites More sharing options...
exchemist Posted May 28 Share Posted May 28 Just now, J.C.MacSwell said: The weight might only increase 5% range when considering the rider and any cargo and not just the bike. Comparable to existing ebikes. Transmission losses would be mostly one way, maybe a few extra percent. That leaves generation and regeneration losses, and charging, discharging and recharging losses (anything else?) vs regeneration recovery and more efficient pedalling overall. I Transmission losses for electric transmission will be nearer 20% I should think. Link to comment Share on other sites More sharing options...
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