gwhy!
100 kW
Please can anyone please tell me how easy is it to incorperate regen braking using a rc setup.
Thanks.
Thanks.
Regen. with an RC set-up.
- Thread starter gwhy!
- Start date
erth64net
100 W
gwhy! said:
I doubt you'd want to; your inertial energy is so low, compared to a car/truck, that the energy requirements (human or electric) of always powering your movement, vs just freewheeling...well...there doesn't appear to be any notable ROI.
But...if you really want to explore this; from what I understand, most brushless ESCs use the battery as your shunt when implementing motor-braking. So, the end-result is any shunted power is shoved back into your batteries (possibly damaging them from a high-recharge rate). I also once read that you risk burning-out your ESC if attempting to utilize this regen/shunt trick over extended distances (ie: used to decelerate from...say...30-->0MPH while running down a steep hill).
MitchJi
10 MW
Hi,
You will need an esc or controller that will work with the RC motor that supports regen (I think that will be a problem).
Left side drive:
No FW on the motor which means your pedaling would turn the motor when the motor is off.
Right Side Serial Drive or Crank Drive:
1. No FW on the motor which means your pedaling would turn the motor when the motor is off.
2. You could not use a hub with a Freewheel . Two examples, easy to disable with the Nuvinci, not with a Nexus.
For the energy returned I agree, just spend another 10% on the battery. But the braking would be really really nice (IMO).
gwhy! said:
You will need an esc or controller that will work with the RC motor that supports regen (I think that will be a problem).
Left side drive:
No FW on the motor which means your pedaling would turn the motor when the motor is off.
Right Side Serial Drive or Crank Drive:
1. No FW on the motor which means your pedaling would turn the motor when the motor is off.
2. You could not use a hub with a Freewheel . Two examples, easy to disable with the Nuvinci, not with a Nexus.
erth64net said:
For the energy returned I agree, just spend another 10% on the battery. But the braking would be really really nice (IMO).
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
One factor about "regen vs. freewheel" that people forget is that when you are trying to coast the freewheel allows the backEMF of the motor to become disengaged. This increases the efficiency of the system because without the backEMF you do not have to expend energy just to overcome the no load current. (just turning the motor means you have to constantly overcome the backEMF)
The regen test is "rigged" in that it compares a hub motor to itself.
To get a fair comparision you need to compare a hub motor to something that can freewheel.
But the hub motor people seem so close minded that I doubt they will ever bother to realize this.
...throw in gearing and the non-hub motored ebikes rule.
The regen test is "rigged" in that it compares a hub motor to itself.To get a fair comparision you need to compare a hub motor to something that can freewheel.
But the hub motor people seem so close minded that I doubt they will ever bother to realize this.
...throw in gearing and the non-hub motored ebikes rule.
gwhy!
100 kW
Thanks guys for the replys . I know some of the esc are capable of braking and I would like to explore a regen option, for my application of a E-trials bike I think it could be worth while . There can be some very long, slow controlled descents in trials riding so I just as well try to put back some energy back into the bats even if is only a very small % I would like to design some form of proportional braking.. I had the electronics worked out for use on a brushed motor but this brushless stuff is all new to me :wink: Just wondered if anyone have gone down this route with regen I don't want to re-invent the wheel.
. I know some of the esc are capable of braking and I would like to explore a regen option, for my application of a E-trials bike I think it could be worth while . There can be some very long, slow controlled descents in trials riding so I just as well try to put back some energy back into the bats even if is only a very small % I would like to design some form of proportional braking.. I had the electronics worked out for use on a brushed motor but this brushless stuff is all new to me :wink: Just wondered if anyone have gone down this route with regen I don't want to re-invent the wheel.
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
I've looked at the math on motor powered braking (regen) and it's not pretty. In order to stop a bicycle at any reasonable rate you need something near 10 hp to get to the point of skidding the tire. The motors we use can't regen anything close to that.
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
Unless you know of some math I don't... a motor can only regen some percentage of the power that it can output in the forward direction.
After all... what is really happening?
In reality the thing that DRIVES the regen (as well as power in the forward direction) is the permanent magnets. There is a limit to the power of the permanent magnets and so that limits the regen.
That's the whole argument about Induction (Traction) motors... they create their own magnetic fields and so you can play around a little more, but for permanent magnet motors it's a fixed quantity.
You would need a motor with magnets strong enough to produce 10-15 hp to be able to get enough of a braking force to replace the brakes completely.
And don't forget this needs to be on the front wheel... which introduces more problems.
It makes more sense on cars...
http://en.wikipedia.org/wiki/Regenerative_braking
After all... what is really happening?
In reality the thing that DRIVES the regen (as well as power in the forward direction) is the permanent magnets. There is a limit to the power of the permanent magnets and so that limits the regen.
That's the whole argument about Induction (Traction) motors... they create their own magnetic fields and so you can play around a little more, but for permanent magnet motors it's a fixed quantity.
You would need a motor with magnets strong enough to produce 10-15 hp to be able to get enough of a braking force to replace the brakes completely.
And don't forget this needs to be on the front wheel... which introduces more problems.
It makes more sense on cars...
http://en.wikipedia.org/wiki/Regenerative_braking
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
There is a long list of problems... it just seems that more research is warranted in other areas. Just getting the RC motor to work right and to have a decent transmission should be the first goal. Regen has so little return value that it's something to push off into the indefinite future.
For hub motors they have little left to develop... so for them it makes more sense to fiddle with it...
For hub motors they have little left to develop... so for them it makes more sense to fiddle with it...
gwhy!
100 kW
The proportional braking worked really well on the off road rc cars that I used to race 20+ years ago on state of the art controllers for the time ( transitors and relays :lol: ) but did not incorperate regen, I designed my own controller with regen that did give me a edge and lead to a winning streak ( well for a little while anyway :lol: )
gwhy!
100 kW
CNCAddict said:
This is what I fear will be the problem. I left the electronics scene 20 years ago and haven't kept up at all with new technologies in this field so it feels like im starting all over again :lol:
recumpence
1 GW
Hmm for trials, I can see some merit. Even if no regen is used, I could definately see how motor braking would be very helpful. It would be a lot better for trials than a freewheel system.
I did quite a bit of research into regen when I was building (or planning) my recumbent. Every person I read about on-line (all 3 of them :wink: ) that used regen on a bike regretted it and ultimately went to a freewheel setup because you regain far less power using regen than you lose in not being able to coast. Unless you are going down hill for long periods of time, regen is not as efficient as coasting to increase your distance per charge.
Again, for trials, I would say regen or at least motor braking with no freewheel would be a good thing.
Matt
I did quite a bit of research into regen when I was building (or planning) my recumbent. Every person I read about on-line (all 3 of them :wink: ) that used regen on a bike regretted it and ultimately went to a freewheel setup because you regain far less power using regen than you lose in not being able to coast. Unless you are going down hill for long periods of time, regen is not as efficient as coasting to increase your distance per charge.
Again, for trials, I would say regen or at least motor braking with no freewheel would be a good thing.
Matt
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
It just seems to me that at best you can get as much back as you put in when you are trying to maintain a constant speed with a regen system.recumpence said:
On Justin's regen thread he's claiming that he actually achieves MORE regen than motor input... which seems impossible. :?
(this is why everyone thinks it's "cool")
Free energy... that has to be good. :lol:
safe said:
He's a pretty smart guy when it comes to electronics and physics. I think you might have misunderstood him(or the electronics or physics) because I'm sure he's well aware of the implications of extracting more energy than what one inputs.
gwhy!
100 kW
swbluto said:
The guy would be worth billions
...I had a Quick think about the regen issues It maybe be possible to use those nasty back emf spikes ( that kills esc's ) and put them to good use ( basically a dc to dc stepup converter ) maybe just putting a little into a getmehome reserve battery. I have not done any maths on this to see if its viable or if its worth the effort but I may do some testing when/if I get a basic rc setup working. Motor braking would be a big plus for a E-trials bike quite rightly as recumpence has said even if no regen is used.
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
My understanding of trials riding is there is a lot of lurching and hopping that takes place. Normally the throttle is cracked wide open for a second, then instantly the brakes are applied. If there was some way for the motor to act as the brake and regen capture everything that would increase your riding time.gwhy! said:
Regen might actually make sense for trials because you NEVER coast.My pet peeve has been that freewheels are not being recognized for the benefits they have for efficiency. In most cases for sport riding the freewheel makes more sense than regen. (especially when you have gears)
-------------------------
The only downside of regen for trials is that apparently high peak surges of power tend to be very inefficient with regen systems. Ideally for regen you need a long smooth moderate downhill... enough to supply more energy (the hill) than the motor wastes... and you want to recapture the energy slowly. Sudden spikes will mostly be lost due to the motor itself and not the battery. (so ultracapacitors will not help much)
--------------------------
I side with recumpence on this one... regen is mostly a loser... I would not waste time with it on an ebike right now...
recumpence
1 GW
I would say it this way;
Regeneration on a bicycle can give a very limited amount of energy recapture into the battery. For very long decents it can be good, or even needed, to save brakes from overworking such as long mountain decents or very long hills. For typical in town riding, there is far more benefit to merely coasting to conserve kinetic energy.
Matt
Regeneration on a bicycle can give a very limited amount of energy recapture into the battery. For very long decents it can be good, or even needed, to save brakes from overworking such as long mountain decents or very long hills. For typical in town riding, there is far more benefit to merely coasting to conserve kinetic energy.
Matt
safe
1 GW
- Joined
- Dec 22, 2006
- Messages
- 5,681
And I would add that if you ride for "Sport" and like going as fast as possible downhill then regen has even less potential benefit. For me staying ahead of traffic is very important and cars tend to speed up (not slow down) when they go downhill. Regen (going really really slow) just makes things less "safe" in traffic. :wink:
On downhills I'm in sixth gear with the throttle wide open.
On downhills I'm in sixth gear with the throttle wide open.
erth64net
100 W
recumpence said:
So, for you, regen is mostly just a low-friction brake. I agree.
The way I look at regenerative braking, in terms of power & energy returns;
1) Let's assume one can get the motor's RPM high enough to reach a battery's recharge voltage rate (for me, that'd be somehow keeping the bike at 30+MPH).
2) Assume 90% efficiency.
3) Realize that you'll only obtain a rough ballpark of 15-20 watts-per-mile (take your existing Wh/mile and subtract 10%).
4) Assume we found a descent that'd allow you to maintain 30+MPH for an entire mile, with the regenerative brake running.
After all this, you've now added a total of...oh let's make this ballpark math easy...15W to the battery, or for a 24V setup, .6 amps. If you're not after a low-friction brake, then why not just freewhell...I'd think you'll get better return on your investment by investing in a decent freewheel and then just strapping a tiny solar panel to the top of your battery pack :?
recumpence
1 GW
Gogo,
That is kind of obvious. However, I do not mean to be harsh in my statements on this. But, if you really do research on this, regeneration recouperates an EXTREMELY small amount of energy. Yes, kinetic energy gets lost as heat in braking. However, so does most regeneration energy.
Regen is useful in electric cars to a useable degree because of the higher speed and FAR higher weight involved. But, with a light weight vehicle such as a bicycle, with existing technology, regeneration is not useful, period.
Again, I do not mean to be harsh. I just want to save people a bunch of time and money trying to get regen setup and useable on a bike, when it does virtually nothing in real world riding.
It is a good theory, but in practice, regen does almost nothing on a bike.
Matt
That is kind of obvious. However, I do not mean to be harsh in my statements on this. But, if you really do research on this, regeneration recouperates an EXTREMELY small amount of energy. Yes, kinetic energy gets lost as heat in braking. However, so does most regeneration energy.
Regen is useful in electric cars to a useable degree because of the higher speed and FAR higher weight involved. But, with a light weight vehicle such as a bicycle, with existing technology, regeneration is not useful, period.
Again, I do not mean to be harsh. I just want to save people a bunch of time and money trying to get regen setup and useable on a bike, when it does virtually nothing in real world riding.
It is a good theory, but in practice, regen does almost nothing on a bike.
Matt
Similar threads
