A little bit of knowledge needed

[Spinalot]

Good morning fellow enthusiasts.

The Storck Raddar system does offer up to 10% regen back into the battery on freewheel automatically. You don't need to activate a switch when braking or anything like that. The system will regen as soon as you stop pedalling, coasting, freewheeling downhill etc. There is no drag or noise. This does help provide a very useful 100klm battery range.

Cheers,
Ian

I am going to mug a Granny to help afford one! (thats only a joke! I am not strong enough to knock a Granny over!)

*edit* Hmmm, just made a coffee and whilst making had this thought.
Why then, Ian, could you not put one of your motors, just the regen part of it, in the front wheel and crank to charge as you ride even more?

 

[flecc]

The Storck Raddar system does offer up to 10% regen back into the battery on freewheel automatically. You don't need to activate a switch when braking or anything like that. The system will regen as soon as you stop pedalling, coasting, freewheeling downhill etc. There is no drag or noise. This does help provide a very useful 100klm battery range.

Cheers,
Ian

Sorry Ian, while I appreciate the excellent way your regen system operates, zero drag is just not true. If you get 10% regen there will be more than 10% regenerative based drag at that time, simple physics. No system is 100% efficient and you are claiming 110%, perfection plus 10% for nothing.

In the circumstances you describe the drag might not be noticed, but that doesn't mean it's not there.

 

[flecc]

Many thanks to all for your attempts at making me understand.

Can you see a time when something could be done

No, nothing can ever be done. What everyone is saying is that energy is never free, it always needs some form of energy put in to get some out. Since perfection is impossible, the amount put in will always be more than the amount got out.

For example, you pedal an unpowered bike up a steep hill and you get hot. You may have been generating 400 watts of effort, but perhaps 100 watts or more was wasted in heating you up, leaving only 300 watts or less pushing the bike along.

This is a simple example of how you always get out less than is put in, there is nothing free.

True in life too. Try getting your bank to lend you £1000 and pay you 5% per annum for borrowing it!

 

[tappy]

Sorry Ian, while I appreciate the excellent way your regen system operates, zero drag is just not true. If you get 10% regen there will be more than 10% regenerative based drag at that time, simple physics. No system is 100% efficient and you are claiming 110%, perfection plus 10% for nothing.

In the circumstances you describe the drag might not be noticed, but that doesn't mean it's not there.

Oops, sorry flecc and everyone, don't mean to mislead. All of our customers, owners and journalist who have ridden the Raddar system including myself (regularly) have said that they have not noticed any drag when freewheeling or coasting on the bike. One thing I forgot to mention is that you get regen back to the battery even when the system is switched off.

Cheers,
Ian

 

[tappy]

I am going to mug a Granny to help afford one! (thats only a joke! I am not strong enough to knock a Granny over!)

*edit* Hmmm, just made a coffee and whilst making had this thought.
Why then, Ian, could you not put one of your motors, just the regen part of it, in the front wheel and crank to charge as you ride even more?

Hmm....I will put that one to Markus Storck when I see him in a couple of weeks time. Jeff you could always do a paper round on your new Storck Radar bike to help afford one. ??

Cheers,
Ian

 

[piotrmacheta]

But 'regen' means 'drag' so there must be some.

 

[Spinalot]

Jeff you could always do a paper round on your new Storck Radar bike to help afford one.

ha ha, I am a bit old for a paper round!

 

[Scottyf]

I just rmemebered the old game on the atari of paper boy. Loved that game throwing stuff at people.


People may not notice the drag. However as flecc says it will be there.

Which is why I wanted to know how much do most units actually create in form of drag. Ie is it like riding under inflatted tires. or maybe its like trying to pedal a spin bike with the resistance up high...

I'd imagine the more resistance the more watts go back into the battery.
However a 10% regen would be useful if say you went down an hill and could capture some of the kenetic force for free ;-)

 

[flecc]

I think the BionX direct drive system is good Scotty, being able to switch in 4 levels of regen depending on circumstance. That makes the best out of any downhill, steep or slight, and the braking effect saves rim and/or pad wear, especially down long hills.

I've only tried it once, but the drag wasn't perceptible to me without the regen.

 

[tillson]

A few things to remember when thinking about regenerative braking:

1) energy cannot be created or destroyed. You can only change it from one form to another and that change nearly always results in changing some of the energy into heat energy. Heat energy is a very low grade form of energy and is usually regarded as wate.

2) regenerative braking is the conversion of kinetic energy into electrical energy and then the conversion of the electrical energy into potential energy. Or, in other words, plenty of scope for loss in the form of heat.

3) with our bikes, the starting point for energy recovery through regenerative braking is the bike and rider's combined kinetic energy. This is the only energy available to be harvested. Kinetic energy is arrived at by multiplying the mass of rider plus bike by the bike / rider's velocity squared. So velocity or speed is important. Double the speed, get four times the kinetic energy.

Unfortunately for us, our speed is low and we don't have much mass either. The net result being that there isn't much energy available to harvest in the first place. Add in the losses of converting it from kinetic to electrical to potential to electrical and ultimately back to kinetic, there is very little if any benefit to be had. It's much better to use the kinetic energy gained going downhill to carry you partway up the next one. This will allow you to save and use the precious useful energy without wasting it at as heat during all of those state changes.

In a nutshell, regenerative braking is a useless gimmick.

 

[flecc]

In a nutshell, regenerative braking is a useless gimmick.

In all it's present implementations, I broadly agree. However, I can envisage a useful form.

Use as a start point the Panasonic front hub motor currently on trial in Japan, which is designed to also be the only front brake operated via a progressive lever.

Now incorporate a freewheel into the hub motor which locks in the first stage of that brake lever operation. This could be an electrical clutch like the old Smiths magnetic clutch that was on some small cars in the 1960s and '70s. As a clutch it failed due to fierce operation, but for my proposed use that is not important.

Now you have a system with no drag on overrun or when pedalling without power, but optimum conversion of all front braking into charge current.

 

[mike killay]

Flecc's idea would work, but just how much useful energy could you capture?
Funnily enough, going back to the original question, a number of people have asked me if pedalling recharges the battery. My guess is that because modern batteries are so small, they do not realise just how much energy is stored in them.

 

[tillson]

The answer is that there is no useful energy to recover and the idea of using regenerative braking to charge the battery or extend range should be forgotten and dismissed from further consideration.

Braking by the application of an electrical resistive load, does have possibilities and advantages worthy of further investigation.

 

[Spinalot]

...they do not realise just how much energy is stored in them.

So can you quantify this? How long would I have to pedal a bike on a stand driving a dynamo for instance?

 

[flecc]

Flecc's idea would work, but just how much useful energy could you capture?

Not a lot, and very variable according to riding technique and territory.

A skilled cyclist doesn't waste lots of energy through excessive braking, and if in flat territory the gain would be miniscule.

On the other hand, a nervous cyclist in a hilly area who brakes all the way down every hill to keep speed low will gain a moderate amount of electrical energy. Of course learning to use the mass of themselves and their bike more intelligently would be more efficient.

 

[Scottyf]

I must admit when riding un assisted I ride with alot more patience and try to...

1) Not to stop at all
2) never use the brakes unless it an emergency

I even try to free wheel a good 100feet away from traffic lights so i can give my legs a rest while rolling to a red light.
When I have electric assistance I use the brakes much much more. mainly becasue i can use the electric to get me back up to speed.

 

[Deleted member 4366]

Imagine going out for a Sunday ride of about 60 miles on an unassisted bike. You'd probably average about 60 watts during that journey at an average speed of about 10 - 12mph (depending on terrain), which would take you about 5 hours. That would be nearly enough power to charge up a 36v 8aH battery. So, if you feel like doing the equivalent of a 60 mile unassisted journey every other day sitting in your living room on an exercise bike without going anywhere , you'd have enough power to ride assisted the next day at a slightly higher speed. That's what regeneration means and is why it's not feasible for most ebikers.
Some bikes have regenerative braking, which more or less gives you something for nothing. Unfortunately, what it gives you is rather closer to nothing than something. That's another reason why hardly anyone bothers with it.
As Flecc said earlier, some manufacturers tried it, but when the punters figured out that it was more of a hindrance than a help, Their sales flopped and it was dropped, bare in mind that most punters and probably manufacturers at the time didn't have a clue what it was all about - but they soon found out.
My advice: forget about it and pay the 8 pence to charge your bike from the mains or start breeding hamsters and make some of those little generator treadmills for them to exercise on. After you have about a thousand hamsters and treadmills you might be able to charge up your battery for nothing in about a week.

 

[mike killay]

If you use an ordinary bike bottle 'dynamo' (apparently they are alternators), Then according to Wiki they give out 3 watts at 6 volts (equivalent to half a watt at 36 volts).
So if you have a 10 amp hour, 36 volt battery, ie 360 watts, you will need to pedal for 720 hours (ie 30 days).
The most efficient of such generators is about 70%, so for every three watts of electricity that you generate, you will use 5 watts of muscle power.