Energy Recovery?

Discussion in 'Help Choosing an Ebike' started by Andy57, Feb 11, 2015.

  1. Andy57

    Andy57 New Member

    Been new, I might of missed threads on this, however here is my question.
    The Electric Mountain Bikes seem to be mostly the motor in the crank, which when mated via a gears/freewheel does not allow regen braking by the existing motor. Now regen braking on flat rides might be worth say 10% increase in range, however on a mountain bike, could be a lot more under the right conditions (one ride we do is up like 20 miles and 4,000' up, but has a few ups and downs on the way, so do need energy to ride back as can be 40 miles with some climbing flat sections near the end.
    So has anyone looked at hub mounted motors/dynamo (like used for lights), either front or rear to give some energy recovery?
    I could see some energy been recovered in a coast mode on the long down hills, either brake lever activated, or maybe operator switched and then turned off by the front brake or peddling. Thus allowing it not to be engaged while actually cornering or climbing.
     


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  3. Wayne

    Wayne New Member

    Energy recovery is a dream still. I am including the Prius in this statement too. Unless you live in the Rockies or similar terrain, it's just added complexity for very little.
     
  4. Mike leroy

    Mike leroy Active Member

    I like the idea. I think servos only generate about three watts.

    Mountain bike only work well with mid-drive motors. I might buy two different bikes. I would like to buy a 1.5kW to blast up a 10% road. I want to outrun the cars in the share lane. The motor will reach 30mph. The speed limit is 35mph. I would love to go faster than gas guzzlers!

    I can run up the hill around 10 mph. The problem with powerful hub motors are their width. The dropout needs to be about 175mm. I am not sure if you can even squeeze a few gears in. I have not tried to find a frame. A better alternative is a Pinion P1.9 fearbox.

    I run two miles to the store and carry 30+ pounds of groceries back. I did it today. Last time, I talked with the owner of a 10kW Honda PCX Scooter. He owned an eBike and is very fit. He bought a scooter because commuting more than five miles was too arduous. The PCX costs less than $4000 and gets 100+ mpg.

    Whatever eBike I buy has to be competitive with the PCX. I am willing to bias my decision highly against gas. I just hate the idea of burning gas. It is like smoking tabacco. The only eBike that I consider competitive is the Grace One.15, due out in Sept 2015.

    My only other road is a fire road that requires a full suspension. Seriously, you could drain the battery three times faster with a hub motor than a mid-drive on the 18% grade.

    Generalizations are dangerous, so take it with a grain of salt. You need to carefully consider each situation in detail.
     
    Last edited: Mar 18, 2015
  5. JayVee

    JayVee Well-Known Member

    One of the Haibike trekking models used to have a dynamo in the front wheel. But they took the feature out in the 2015 model. Not sure why. As for hub motors, many offer energy recuperation on hills or during braking. I've used this often with GoSwiss drives. It's extremely useful if you're a little short on range. You've got to be quite disciplined to use regenerative braking whilst stopping though. Depending on the model, if you pull the brake lever gently it will use regen instead of the brakes. There are several regen modes, and I've found that on average I would recuperate roughly 1 kilometer worth of autonomy for every 5 kilometers of downhill travelled on a given hill and at a given speed. These figures are estimates based on percentage of battery usage during the same daily commute. As for regenerative braking, if you stop often during your commute, its a good idea to use it because it compensates for the energy lost whilst restarting the bike. Frequent traffic lights are a battery drainer, and regen can help minimize that effect.
     
    Mike leroy likes this.
  6. Joe Average

    Joe Average New Member

    Why is a 5 mile commute too hard for a fit man? I'm doing it with a very unfit body for 8 miles each way through hilly country with a BBSHD Lunacycle 48V on an entry level mtb turned commuter.
     
  7. rich c

    rich c Active Member

    Extending the range by 10% with regeneration? You sure about those numbers? Considering it takes 3+ hours to recharge my battery pack by being plugged into the grid, your numbers seem quite optimistic. I see no reason at all to have regeneration on a bike. The real amount of electricity getting back to the battery has to be minimal. Now on a 2500 pound car going 60mph, I can see it. But on a bike, purely pipe dream in my opinion. I also agree, there are way different opinions what fit must be. 5 miles is just about a warmup for me, and I'm 65 and not that fit!
     
  8. JRA

    JRA Well-Known Member

    I use a momentary switch to activate the regen on my bikes primarily as a drag brake and have it positioned where it and the brake lever can be applied at the same time easily.

    It is the red bottom on the left hood
    9C281A63-17AC-4595-836F-49B69C7E300F.jpeg
    There is some minimal recharging of the battery but not enough to make any type of difference in range I find.