Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Electric Bikes Here's a place to discuss ebikes, from home grown to high-tech.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 01-10-10, 03:50 PM   #1
Tipjar
Newbie
Thread Starter
 
Join Date: Jan 2010
Bikes:
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Question Electric bike alternators?

Hi,

I'm just starting to look at electric bikes, and learning what some of the differences are among them...

I notice the energy from the disc brakes can be channeled back into charging. I also notice most of the hub-motor models will only have a drive unit on one wheel (I'm guessing to avoid overkill, and keep the other wheel available for a disc brake rotor).

Has anyone come up with alternators to fit in the non-motorized hub and/or the pedal assembly for channeling energy back into charging? After all, those parts are already in motion. I'm not familiar with the ins-and-outs of alternator design, but I'm wondering if a brushless alternator would have significantly less resistance, allowing it to give more energy than it takes?
Tipjar is offline   Reply With Quote
Old 01-10-10, 04:20 PM   #2
nwmtnbkr
Senior Member
 
nwmtnbkr's Avatar
 
Join Date: Jul 2009
Bikes:
Posts: 1,054
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Not that I've seen. The amount of regenerative energy generated in those systems that have it built in isn't that much, either. Hence the eternal quest for as much energy as you can pack into a battery while keeping the weight down. The most sophisticated e-bike is a German hybrid called the E-Rocket that will be beyond reach for most since it's price is over $40,000 USD. From an article here: http://www.cens.com/cens/html/en/new...ner_27291.html "The eROCKIT has a serial hybrid propulsion system that lets the rider control the motor speed through a crank assembly and an inter-connected generator. The generator monitors the rotation of the crank assembly and sends an output signal to the control electronics according to the rider`s peddling speed. The control electronics steers the electric motor with the received signal as a reference point. The faster you peddle, the faster the motor rotates the rear wheel. The generator thus has a double role of sending signals to the control electronics and transferring the peddling force into electricity to recharge the battery."

The E-Rocket doesn't have a throttle; you have to peddle to make it move and have power assist kick in, but its hybrid propulsion system can amplify the cyclist's pedaling power to reach speeds of 30-50 MPH.
nwmtnbkr is offline   Reply With Quote
Old 01-10-10, 04:55 PM   #3
wernmax
Certified Non-Voter
 
wernmax's Avatar
 
Join Date: May 2008
Location: Colo Springs, Colorado
Bikes:
Posts: 256
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 82 Post(s)
Quote:
Originally Posted by Tipjar View Post
Has anyone come up with alternators to fit in the non-motorized hub and/or the pedal assembly for channeling energy back into charging?

Ahh....the age old idea of coupling a generator onto a motor for endless power. A classic.

Stupid old physics always getting in the way of good idea.
wernmax is offline   Reply With Quote
Old 01-10-10, 08:14 PM   #4
crichman
Member
 
Join Date: Sep 2008
Location: Bethesda, Maryland (just outside Washington DC)
Bikes:
Posts: 32
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Of course, there are existing hub motor systems that provide regenerative braking, like Bionx (and now Trek.) You don't need a separate generator, just a drive unit that doesn't freewheel and an appropriate controller.

The amount of energy recovered isn't huge, but the reduced wear on your brakes can be a plus.

Charlie
http://ElectricCyclist.com
crichman is offline   Reply With Quote
Old 01-11-10, 11:26 AM   #5
Mabman
Senior Member
 
Join Date: Oct 2008
Location: The F/V Misty Moon/Clatsop Co. OR homebase
Bikes: Some
Posts: 206
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
This effort comes as close as I have seen to what you envision. http://www.youtube.com/watch?v=eknnz...fresh+div-f-15
Mabman is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 06:04 PM.