- #1
- 10
- 0
I want to make kers for my two wheeler.How should i start and what are the things that i should consider??
How to make KERS (Kintetic Energy Recovery System) for 2-wheeler?
In summary, the biggest challenge is that most states have weight and speed limits on electric bikes, which cuts deeply into the amount of energy a flywheel can store. A properly enclosed flywheel should not draw much restriction, other than if speeds of the flywheel cause control problems related to resistance to lean or turning.f
- #2
- 363
- 21
Is it an electric two wheeler?
- #3
Doug Huffman
Gold Member
- 808
- 111
Ahh, KERS (capitalized abbreviation) for Kintetic Energy Recovery System.
Consider its required capacity and power (time rate). 100 kg from 50 kph to zero at 1/3 g for a bicycle HPV.
Consider its required capacity and power (time rate). 100 kg from 50 kph to zero at 1/3 g for a bicycle HPV.
- #4
- 10
- 0
how does that matter?
- #5
- 363
- 21
What you have to start with matters...
Read about regenerative braking and I think you'll understand.
- #6
- 479
- 33
Not true. The link shows that you can do this with a regular bike and a bit of ingenuity.
http://www.gizmag.com/flywheel-bicycle-regenerative-braking/19532/
- #7
RonL
Gold Member
- 1,106
- 216
That's a great proof of concept, but for a 15 pound flywheel at any significant rpm, the support is just not good (Imho)
I say this only to raise awareness for anyone that might just jump up and throw something together 
:)- #8
- 479
- 33
I totally agree. It's shows good thinking and it's all mechanical, but I don't quite see the allure of carrying around 15 extra pounds on a bike just to save you maybe 10 percent of the energy you expend. This link is a sexier version of the electric bike conversion kit: https://www.superpedestrian.com/. I think this might be closer to something people might invest in (but I'm not a cyclist).
- #9
RonL
Gold Member
- 1,106
- 216
I have always liked the Hub Motor for electric, but the idea of flywheel energy storage for take off assist, is high on my list of ideas.
Biggest challenge is, most states have weight and speed limits, which cuts deeply into energy storage density.
Biggest challenge is, most states have weight and speed limits, which cuts deeply into energy storage density.
- #10
- 363
- 21
Does the OP want a purely mechanical system? If the two wheeler is electric, a simple regen system might be easier.
We still don't know if Op is starting with a gas motorcycle, pedal bike or electric bike. It matters.
We still don't know if Op is starting with a gas motorcycle, pedal bike or electric bike. It matters.
- #11
- #12
- 479
- 33
Speed limits on how fast the flywheel can turn? I was about to suggest a carbon-fiber flywheel. It's light enough to be worthwhile but you can get that thing to spin up really fast. If there's limits to flywheel speed, then that's out.
- #13
RonL
Gold Member
- 1,106
- 216
No!, the speed and weight generally apply to electric power and a limit of around 700 watts at the motor.
A properly enclosed flywheel should not draw much restriction other than, if speeds of the flywheel cause control problems related to resistance to lean or turning.
- #14
berkeman
Mentor
- 65,552
- 17,355
Oh Jeeze! I didn't think of that. A spinning flywheel on a bicycle (road or MTB) could be a very bad thing. Maybe if it could gimbal it wouldn't be a problem. But that would make getting energy into and out of the flywheel much more difficult...
- #15
RonL
Gold Member
- 1,106
- 216
It might be that a second flywheel spinning in the opposite direction would solve most of the problems, however that begins to increase the engineering design efforts of dual input and power take-off applications.
- #16
berkeman
Mentor
- 65,552
- 17,355
Ah, good idea! :-)
- #17
- 479
- 33
Yeah the engineering would have to be more significant, but you'd have to do some sort of "balanced system" like that to make it work.
- #18
RonL
Gold Member
- 1,106
- 216
Looking at road construction concrete saw blades, you can find a blade 28" diameter and about 1/8" thick with a weight of about 15 pounds.
Mount one on each side of the frame and there will be little to indicate there are two flywheels, they are rated around 2500 RPM (while making cuts in concrete) the energy storage for a bicycle should be pretty generous. Just a quick thought :)
New they price from $800.00 to as much as $1500.00, on some occasions a concrete contractor will give them away and not bother having them reconditioned.
- #19
berkeman
Mentor
- 65,552
- 17,355
I'm not adding no 30 pounds to my bike! :w
- #20
Bystander
Science Advisor
Homework Helper
Gold Member
- 5,493
- 1,592
"Ten per cent?" This is for some sort of "Hare & Hounds" cross-country, steeplechase obstacle course? Two seconds on the throttle, two seconds on the brakes until you're seasick?
- #21
- 363
- 21
We don't know. It is a secret.
- #22
- 479
- 33
Don't quite get what you mean. I haven't done any real number crunching, so 10% was a number I picked out of thin air. I can't imagine a system like this saving more than that amount of energy. Maybe I'm wrong though...it's been known to happen :-)
- #23
Bystander
Science Advisor
Homework Helper
Gold Member
- 5,493
- 1,592
Back of the envelope bookkeeping on recovery systems just for ordinary driving, I couldn't begin to get 5% for "soccer moms" doing "stop and go" all over town, let alone pay for hauling the additional mass necessary for the recovery around.
- #24
- 479
- 33
Totally agree.
Suggested for: How to make KERS (Kintetic Energy Recovery System) for 2-wheeler?
Automotive
Total machine system efficiency