Charger from hub motor

I had a new idea and i would like your proposals about it.
I want to use a hub motor in my wheels which it does not work to move the bike, but i want to make power from it when the e-bike is moving.
Can i use the hub motor as a charger for the Lifepo4 battery when the e-bike is moving? The motor in the e-bike will be mid drive.
Below are the questions i have:
1. If i connect the hub motor to the battery with a rectifier can i use it as a charger for a lifepo4 battery at 48Volt or 72Volt?
2. Have you ever tried it?
3.Can you please tell us what kind of rectifier this kind of charger needs?
4.What is your view about it?
5.What kind of volt (as 12V, 24V or 48V) ? And watt (as 100watt , 50watt) will this hub motor gives? I am sure this depends from the speed and other things, is that right?
6.Can the 100A kelly controller used as a rectifier?
7.Which hub motor will be the best to use as a charger for a 48Volt or 72Volt Lifepo4 battery?
8.Do you think i will find a lot of difficulties fixxing the above charger?

Thank you for your answers

why not just use an regen on your mid mount motor ?

you can only use it as a ebreak anyway

(if you power one motor and charge from another motor, you'll loose power as friction/heat etc.. and use more power than you generate)

knighty said:

why not just use an regen on your mid mount motor ?

you can only use it as a ebreak anyway

(if you power one motor and charge from another motor, you'll loose power as friction/heat etc.. and use more power than you generate)

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I use regen in the mid drive bike. I want more free energy to come to me. Its free, what is the reason for not using it? It can come from the wheel

Its not free! and never will be

skeetab5780 said:

Its not free! and never will be

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What do you mean its not free and it will never be free?

You will spend more in food energy to generate it than if you just charged from the wall outlet.

it will work as long as you do not use it while the electric mount motor is working.

If you only use it while you are pedalling or going downhill..it will slow you down and make pedalling a lot harder, but it will charge the battery a very very small amount.

So if your aim is to make a bicycle that is harder to pedal than a normal bike, then yes it will work.


Imagine you are riding the bike with electric power...and not using your charge system from the front wheel. To travel 10 miles you may use, 5 Ah from your main battery.

If you rode the same 10 miles with your charger system working...you would burn maybe 8 Ah from your main battery...and your charger would generate maybe 1 Ah or less if you are very lucky.


The only use for a charge system on an bike is to act as a break to slow you down.

You can not get energy from your charger for nothing...if you take power from it, it will slow you down.

These "free energy" topics keep popping up. If you missed some physics class just invest some time in reading about it.

I don't think I completely understand but if you are already using the mid-drive with regen, adding another motor as a generator will not add anything as far as I can tell. The "free energy" you will be creating with the second motor will be taken from the regen that the middrive that is already creating. That is, you will generate energy from the hub motor, but less from the mid-drive so no net gain.

It has been discussed a lot here, but due to the numerous opportunities for losses, regen only recovers a small fraction of the energy spent to get you to whatever speed you are at when you use the regen, something like 5-10% is in the ballpark. You are much better off coasting, if you can, to avoid wasting the energy you've already spent.

On the other hand, I love regen for braking since it saves wear on the brake parts and it is just cool to have the bike slowed magnetically. Some people don't like it though. To each his/her own.

It's about the same question as asking why you can't attach a wind generator propeller to your bike and harness "free" wind energy. You lose more in drag than you gain.

turbobikekit.com said:

I had a new idea and i would like your proposals about it.
I want to use a hub motor in my wheels which it does not work to move the bike, but i want to make power from it when the e-bike is moving.

Can i use the hub motor as a charger for the Lifepo4 battery when the e-bike is moving? The motor in the e-bike will be mid drive.

Click to expand...

If you mean as regenerative braking to slow you down and add a tiny amount of charge back to your battery (a couple of percent, at most, usually), it'd work fine, but it's a lot of weight and complexity just to get that without using it as a motor, too.

If you mean to get power while you are riding, remember that you are slowing down your forward motion while pulling power from it, which is a waste of your battery power, and if you are trying to recharge your motor battery from it while riding, it's a complete waste becuase of the huge energy losses involved in hte multiple conversions of power.

See the numerous threads about htis kind of thing in "alternative energy" and elsewhere on the forum and internet.

pdf said:

I don't think I completely understand but if you are already using the mid-drive with regen, adding another motor as a generator will not add anything as far as I can tell. The "free energy" you will be creating with the second motor will be taken from the regen that the middrive that is already creating. That is, you will generate energy from the hub motor, but less from the mid-drive so no net gain.

It has been discussed a lot here, but due to the numerous opportunities for losses, regen only recovers a small fraction of the energy spent to get you to whatever speed you are at when you use the regen, something like 5-10% is in the ballpark. You are much better off coasting, if you can, to avoid wasting the energy you've already spent.

On the other hand, I love regen for braking since it saves wear on the brake parts and it is just cool to have the bike slowed magnetically. Some people don't like it though. To each his/her own.

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Where can i find a barke like this? Because i have test a lot of brakes and i am melting all of them, i am fully interested for that idea

turbobikekit.com said:

Where can i find a barke like this? Because i have test a lot of brakes and i am melting all of them, i am fully interested for that idea

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Do you mean "BRAKE" I guess you do.

You do not 'find a brake like that, you already have that brake it is the motor that drives the bike. It is also the brake. When you cut power, if you have the correct controller and a direct drive motor, the bike turns the motor and this acts as a brake

Yes thank you
I wanted to say "brake". So the discussion want to another place as brakes now and i have some other answers now
A. The Cyclone motors does this work with 100A kelly.
But i wanted to say that i want a more hard brake in my front wheel because pads are melting. I have tested 3 brakes. A Avid juicy 3 , clarks exo skeletal and Avid elixir 5, all with 200mm disks diameter.
All of them melting.
B.1. Toyota in their last model had put dynamos at the wheels to take some energy from them at low speeds until 50km/h i think.
What is your orinion to put a dynamo of 12v-24v at the chain of the 2 motors with a small gear of many teeth, so i can use it as a charger in big speeds with capacitors to pull bigger ammounts of energy and release it when the bike stopes?
This can charge enough the battery i think.
B.2.You think that the charger will take a lot of power?
I think this is a better idea than the hub motor as a generator.
Your view ?

turbobikekit.com said:

Yes thank you
I wanted to say "brake". So the discussion want to another place as brakes now and i have some other answers now
A. The Cyclone motors does this work with 100A kelly.
But i wanted to say that i want a more hard brake in my front wheel because pads are melting. I have tested 3 brakes. A Avid juicy 3 , clarks exo skeletal and Avid elixir 5, all with 200mm disks diameter.
All of them melting.
B.1. Toyota in their last model had put dynamos at the wheels to take some energy from them at low speeds until 50km/h i think.
What is your orinion to put a dynamo of 12v-24v at the chain of the 2 motors with a small gear of many teeth, so i can use it as a charger in big speeds with capacitors to pull bigger ammounts of energy and release it when the bike stopes?
This can charge enough the battery i think.
B.2.You think that the charger will take a lot of power?
I think this is a better idea than the hub motor as a generator.
Your view ?

Click to expand...

I am not clear if you want to use the regen as braking, or as a way to recover energy, or possibly both. As far as I can tell, there is very little reason to add significant complication to your drive train soley to recapture the energy when braking. The efficiency of the conversion is not high and most people do not have routes that allow for a lot of recovery. If, however, you go downhill for long periods that require braking anyway, this might be worth it. As to whether adding a hub motor (sounds like you already have a cyclone for the drive system) or a special generator is the best solution, I don't know. It would be interesting to see what someone comes up with. The idea of using capacitors to capture the energy is intriguing but could be cost prohibitive. I don't know of anyone on the forum who has added regenerative braking by adding a generator to a cyclone setup. Personally, it sounds unnecessarily complicated to me, but perhaps not.

As far as regenerative braking, a hub motor works pretty well for that. If you have a cyclone motor, then you know it can't do regen braking because of the freewheels in the powertrain.

Finally, I just want to be sure that you are not planning to recover energy while providing energy to the cyclone motor. If you are providing battery energy to the cyclone, you need energy to move. You can't simultaneously require energy to move and harvest energy without requiring more net energy. Well, you can try, but the first law of thermodynamics prevents it. If this is the case, there is no point in going further.

That's your problem, you can't get regen braking with a motor that freewheels.

You could add a hubmotor to the bike, then having a dual motor bike, you'd not only have some more potential forward power, but you could also do some regen braking as well.

The other option would be to move on up to motorcycle type wheels, getting the motorcycle brakes in the process.

turbobikekit.com said:

Yes thank you
B.1. Toyota in their last model had put dynamos at the wheels to take some energy from them at low speeds until 50km/h i think.
What is your orinion to put a dynamo of 12v-24v at the chain of the 2 motors with a small gear of many teeth, so i can use it as a charger in big speeds with capacitors to pull bigger ammounts of energy and release it when the bike stopes?
This can charge enough the battery i think.
B.2.You think that the charger will take a lot of power?
I think this is a better idea than the hub motor as a generator.
Your view ?

Click to expand...

A. Thanks for the suggestion about the brakes. I think i will go to motorcycles brakes with rims. Do you know a way to put them as a pattent?

B. I will put a dunamo of 12-24volt at the chain between the 2 mid drive Cyclone motors of 2400watt. This dunamo will do the job of a generator with a rectifier, some capasitors will hold the bigger ammounts of energy when the bike stop and will release all the time the energy to charge the battery. So the voltage at the most points will be stable. The charger will take my energy and charge it. The dunamo will have a few or a lot of teeth because i dont want to difficult the move of the dual motors. What do you think?
Thank you

turbobikekit.com said:

will hold the bigger ammounts of energy when the bike stop

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Does your rear wheel turn the motors? Probably not. So you can't use the cyclone for regen that way because there is a freewheel (or two) in the way.

Placing a generator between the motors will use more energy than it creates - your motors will have to use 100W to create 50W. And you don't even get the regen braking advantages.

@Turbobikekit: Each of the ways you can think of (and have posted so far) of trying to recapture power *while moving* all have the same flaw:

While you *could* tap mechanical power from anywhere you like in the drivetrain while the bike is being driven by the motor, and convert that back to electrical power, the losses from doing so are so much that you will be *draining the battery faster* and NOT recharging it, by doing this.

The only way it will be possible to not *waste* power instead of recapturing it is to use regenerative braking of some form, where you can tap into the power that would be otherwise wasted as heat while you slow down anyway.

But you cannot take it from the motors while driving the bike forward, or else you are wasting hte power, not recapturing it, again, because of efficiency/losses in every conversion from one form to another.

You have to take it from the wheels of the vehicle *as you slow down*--if you try to take it from the wheels or any other part of the drivetrain while you are trying to maintain a constant velocity, cruise, coast, or accelerate, you will begin slowing the vehicle down, and then have to *use up (waste) more power than you can possibly get back from the process* to maintain that velocity, cruise, coast, or accelerate at the same speed/rate you had been before stealing energy from the drivetrain or motion.


Again:

See the numerous threads about htis kind of thing in "alternative energy" and elsewhere on the forum and internet. "over unity", "free energy" is what you are trying to get, and it doesn't work.