How does regen work?

[amberwolf]

If you want braking without putting it back into the pack, you'd have to setup what is called Plug Braking, sometimes done with coils of wire wrapped tightly around the bike frame (to help dissipate the heat), and then a switch is setup to do this in extremely rapid succession, in this order:

--turn off controller output (ebrake or other disable line)
--disconnect motor phase wires from controller
--connect motor phase wires to plug braking coils

These coils are setup for some amount of resistance (impedance) so it's not quite a dead short, so you get a smooth non-lockup braking effect at whatever your max speed would be. They are wired to essentially short across the motor phases, which produces extreme drag on the motor, and very effective braking.

You could also set it up so only two phases are shorted rather than three, for higher-speed braking, then at some lower speed limit it engages the third phase short, too, increasing the braking effect notably higher than would be safe from the higher speeds. (assuming you setup the two phases to be sufficient at the higher speeds).

 

[parmenps]

Hey,
I have a question how works regenerative braking on a e-skateboard?
and how most i make that ?

 

[izeman]

how would regenerative braking depend on the vehicle it's installed in? it doesn't matter if you put a motor into generator mode on and ebike or a scooter, or a skateboard. or did i misunderstood your question?

 

[tomtom123]

how does it work and does it work with any out there motor? i know in cars there is a computer that reverses the direction of spin of the motor to generate electricity and put it back in the battery. In ebike it probably works similarly but how does the motor know to reverse and etc... If anyone can give me more details on regen braking on ebikes, it would be great.

also, i have a yescomusa 1000w motor on a cheap walmart bike.. http://www.ebay.com/itm/Rear-Wheel-Electric-Bicycle-Conversion-Kit-24V-36V-48V-250W-500W-700W-800W-1000W-/290754592384?pt=LH_DefaultDomain_0&var=&hash=item43b252fe80

and i'm using this battery http://www.bmsbattery.com/48v/496-48v-10ah-lithium-ion-electric-bicycle-battery-pack.html

How do i make enable regen braking on this motor? if possible at all? what extra items do i need? do i need Cycle Analyst at all or can i use something less expensive? thanks!

 

[dogman dan]

As a simpleton, I understand it like this. If you apply power to the motor, it's a motor and it spins. If you spin the motor, it's a generator and power is created. I think this is true of all motors. The notable exception on a bike motor is the planetary gearmotor. The gearmotor has a clutch inside that lets the motor freewheel when coasting. So then no motor movement when coasting, no generation. Only direct drive hubmotors can regen. Your kit has a dd motor so your motor is ok.

I don't know if regen is possible with the bms in your battery. Some can take none.

On a bike, your controller may or may not be equipped to make use of this power, sending it back to the battery. I don't know if the yes kit can regen in stock configuration, but I bet some folks here know how to make it into a regen capable controller.

On any ebike with a direct drive motor, just letting off the throttle will create some drag if you are moving. You can use this to somewhat control descent speeds on hills. The faster you are moving, the more of this drag you will feel. So descending a hill, you may reach 35 mph or so and no more, while the same hill on a regular bike you may hit 50 mph.

But in a motor with regen braking enabled, the drag is more than the coasting drag on a non regen setup. I don't know why that is, but apparently the braking effect is increased when the load is able to dump into a battery. Something to do with back EMF? More load will cause more braking effect, so a big motor will regen brake stronger than a tiny one.


Well, I made a hash of that. I hope somebody else does better.

 

[tomtom123]

As a simpleton, I understand it like this. If you apply power to the motor, it's a motor and it spins. If you spin the motor, it's a generator and power is created. I think this is true of all motors. The notable exception on a bike motor is the planetary gearmotor. The gearmotor has a clutch inside that lets the motor freewheel when coasting. So then no motor movement when coasting, no generation. Only direct drive hubmotors can regen. Your kit has a dd motor so your motor is ok.

I don't know if regen is possible with the bms in your battery. Some can take none.

On a bike, your controller may or may not be equipped to make use of this power, sending it back to the battery. I don't know if the yes kit can regen in stock configuration, but I bet some folks here know how to make it into a regen capable controller.

On any ebike with a direct drive motor, just letting off the throttle will create some drag if you are moving. You can use this to somewhat control descent speeds on hills. The faster you are moving, the more of this drag you will feel. So descending a hill, you may reach 35 mph or so and no more, while the same hill on a regular bike you may hit 50 mph.

But in a motor with regen braking enabled, the drag is more than the coasting drag on a non regen setup. I don't know why that is, but apparently the braking effect is increased when the load is able to dump into a battery. Something to do with back EMF? More load will cause more braking effect, so a big motor will regen brake stronger than a tiny one.


Well, I made a hash of that. I hope somebody else does better.

Which battery do you know of can be used in regen? can hobbykinglipos by used to regen? what bms would i need?

ALSo, how does the motor know to reverse spin and go into regen mode when you let off throttle? or is the reverse spin automatically done do to the momentum of the wheel?

 

[999zip999]

It dosn't reverse spin, just spinning it makes will make power enough to turn on your ca work with no battery.

 

[wesnewell]

As dogman pointed out, all DD hub motors are capable of regen. The key to using it depends on the controller you have. Unfortunately there are many different controllers out there and regen gets enabled on them in many different ways. The EB215 controller that came with my 48V 1000W motor needed the BK pad jumped to ground to enable it and then the normal ebrake function activated it . The controller I use now already had it enabled, and running the X pad through the ebrake switch activated it. If you want to know how to get it working in your controller, you're going to have to ask about your controller since I'm sure they don't ship the same controller with the kits now that they did years ago when I bought mine. Your bet bet of finding the answer is with a thread titled like this "Enabling regen controller XXXX that came with yescom 1000W kit" or just edit your first post here as I did above.
Then take many pictures of the insides and post them. If you get lucky, someone has already done it and will reply. If not you will probably get some suggestions to try.

 

[dogman dan]

As for the battery, any battery with no bms would be able to receive regen. I have no idea about your battery.

The bms equipped batteries I have owned could only tolerate 5 amps of regen current. That was the max input they could take without overheating something in the circuit. Those were signalab bms's.

 

[docnjoj]

My regen in the new S12S controller is a grey wire loop that you split to enable it. Basically it "shorts" 2 phase wires (no current flowing and throttle closed) for a second and the bike slows down a bit and then it cuts off and the motor continues to roll. I like it but I know there are more powerful ways to do it that really can "stop" a bike down to about 5-10mph. John in CR has used this in a very powerful way cause his bikes can do over 60 mph.
otherDoc

 

[doctorGONZO]

Some of the electric motors or generators in common commercial use electromagnets to provide a magnetic field. forget about them. All the motors used on bicycles contain permanent magnets and therefore always have a magnetic field in the motor.

The basic principle at work is that the permanent magnet magnetic field reacts against the induced magnetic field created when current flows in the coils. The reaction between the two fields causes a movement, making, depending on the design of the motor, either the magnets or the coils to move; making the motor turn.

Another principle is always simultaneously working: any time a conductor is in the presence of a magnetic field of varying strength a current is created in the conductor. This is the way generators work. In a bike motor, all the while the motor is fed current and is turning, the wire coils are feeling a varying magnetic field from the relatively moving magnets and are having a current made in them. This self made current opposes the motion of the motor. It always happens in all electric motors.

So, while you are riding your bike, the motor is SIMULTANEOUSLY burning up battery current to move your bike, and ALSO, being self-braked by its own automatic self generating action.

When you are moving and close the throttle, if your bike was a bare bones simple mechanism with no controller, you would no longer have battery current in the motor, but WOULD still have the motor acting like a generator and causing an automatic braking drag.

There is only one way that a bike motor could supply greater drag than the automatic self-generator drag.....If the controller actually REVERSED the flow of battery current, the motor would then try to turn backward! You would be burning up battery current to give you a brake.

In order for you to get regen the automatic self-generating voltage must be higher than the voltage of the battery at that moment. A sophisticated controller could "invert" the output voltage of the motor/generator to always push more charge into your battery. But too much voltage can be BAD NEWS for the health of the battery so is often not done.

So, you can always get, in theory, automatic self-braking on a closed throttle.
You can always get stronger braking if your controller is designed to run battery current backward to try to turn the motor backward.
Your controller may or may not be designed to change the output voltage of you motor-turned-generator to always add more charge to your battery

Have a nice ride. Really.
.

 

[blackjackel]

I had no idea that regenerative braking was possible on electric bikes till today. I did a search of the wiki and a quick forum search and was surprised to find no singular post talking about the basics and how it works ( I may be bad at searching though). Anyways...

As I understand regenerative braking in general, it works the same way that electric generators are used to create electricity, an electric motor is essentially a generator.. HOWEVER, electric generators spin magnets at extremely high speed in order to generate an electric charge.

The way electric breaking works on cars (as I understand it) is done using gearing, so the gears are used to turn a slow rotation and kinetic energy into a very fast rotation by the magnets (or coil).... this generates a substantial enough energy that is then fed to a capacitor and then into the battery to charge it. The "braking" effect is caused by the conversion of the gears

So I don't quite understand how electric bicycle regenerative braking to work.... There are no gears inside the motors that turn the rotational energy into spinning a coil or magnet very fast... are there? If gearing doesn't exist to do this, then how is one to experience the "braking" effect that is derived out of the conversion of the kinetic energy into rotation energy? Does this happen without the gearing? And if it does, wouldn't that mean that the energy derived out of it would be miniscule and insignificant?

Regardless of how it's implemented, is regenerative breaking on electric bicycles worth it? Do you gain enough energy out of braking to go that much further on a single battery charge? What would you say is the percentage of energy recovered from regenerative braking on e-bikes?

I may be completely wrong in what I said above, and if I am, please feel free to correct any misconceptions that I may have. I'd love to hear about how regenerative breaking works in the context of electric bicycling. If there's a post that explains my answers, feel free to link me.

 

[Ykick]

DD hub motor simply acts like a 3 phase generator. The same controller which drives the motor from the battery can push regenerative coasting power back into the battery. However, in the real world. it's a small amount of power actually reclaimed and it often stresses the dropouts and and motor mounting enough that special precautions need be employed.

Even if/when you prevent (clamping torque arms) the axle from twisting back & forth, it may eventually twist the axle into 2 pieces anyway.

I avoid regen, not worth all the effort for my situation.

 

[John in CR]

blackjackel,

It doesn't have to spin fast. Look how slow wind turbines turn and some of those are direct drive, not geared for a high rpm. It all depends on the design and rpm of the motor/generator.

 

[parabellum]

Breaking itself is made by shorting the coils, regen by redirecting BEMF impulse to the battery at unshorting the coils(this way raising the generated V over bat.V) , then repeat in controlled sequence. Think buck converter.

 

[amberwolf]

I did a search of the wiki and a quick forum search and was surprised to find no singular post talking about the basics and how it works ( I may be bad at searching though). Anyways...

There are actually quite a few threads discussing exactly how it works with various motors and controllers. I suggest using "regen brak*" as your search term. First search using Topic Titles/subjects only, and return results as Topics/threads. If you don't see the ones you expect in there, try searching by message text (and titles if you wish), and return results as posts or as threads.

The "braking" effect is caused by the conversion of the gears

Nope. Caused by load on the motor/generator. See the various threads about it for details.

There are no gears inside the motors that turn the rotational energy into spinning a coil or magnet very fast... are there?

There are in geared motors, but most of those have freewheels or clutches so they won't do regen braking anyway. A few (like an old Fusin I have here) do. There's a lot of existing discussion on the forum about that, too.

If gearing doesn't exist to do this, then how is one to experience the "braking" effect that is derived out of the conversion of the kinetic energy into rotation energy?

Braking is not caused by that. Braking is caused by loading the generator. See above.