Electric Skateboard Regenerative Braking | Testing 

Even though regenerative braking doesn't add too much back to the battery, it's a lot better then depleting your battery in order to break

I think there is a minimum speed required to regenerate . I have heard that 10mph was a target speed maybe you were going too slow

I was hoping someone tried this. AWESOME!

First off, excellent video. I am really glad that you had 2 different trials and 2 different boards to test. This is quite frankly one of the better explorations of this topic applied to electric skateboards. Secondly, You should look into something called an Eddy Current. This is when a changing magnetic field drives an electrical current within conductors. Essentially when you are freewheeling you are generating solely eddy currents. This is the principal that all power generation uses by spinning some form of generator. When you are applying the brakes you are expending electrical energy to reduce your speed. Because you were still moving downhill you would recover some energy, but it won't be nearly as much as if you were free wheeling. Many times I think the manufacturers realize that even when you are freewheeling you still experience some form of braking more than you would on a regular longboard and that's why they dub it "regenerative braking". Also I had a couple of questions... Regarding the difference in heat between the two boards, what hub motors are on each board? Are the hub motors the same rated power? I imagine that the difference in their hill climb performance and their heat generation has to deal with the power ratings and the efficiencies of the motors more than what type of speed controllers you are using.

Going too slowly may not create enough friction around the stator in the BLDC motors to make return power to the bms to charge the batteries. Too much brake force actually uses a lot of the power you just gained. Regen braking is just using the motor(s) backwards literally as generators and the friction created becomes the brake force. I think belt driven setups create more energy than hub motors in most situations due to the reverse gearing as well. Also some batteries charge faster than others. That would be a cool comparison test too.

.. I have a hybrid suv.. From experience you need to either be going fast and lightly brake or full brake. Basically it comes to torque and rpm of the wheels. If you're going slow basically nothing happens. You should try going at a decent speed and then full brake or mostly brake. VS light brake at slow speed.

It's the same situation on electric bikes. Most builds don't even bother including regen braking now. I think it boils down to DC electric motors being very inefficient generators. On electric cars, it's different. They use AC motors with a converter. The converter is massive. We couldn't possibly have that.

I know I did a similar tests where I walked uphill three times and then rode my electric skateboard down while braking. And I gained two bars by doing so. It is good to know that you could charge your electric skateboard without an outside source if you absolutely had to. 😎

Very nice test and video ! I had the same question. Manufacturers say "regenerative breaking" but I think it is more effective as freewheel. I disassembled an electric skateboard having "regenerative breaking" feature because I wanted to check if freewheel can regenerate current back to the battery. Actually I measured a generated current while it is use as freewheeling (no acceleration, no breaking, so push the board or go downhill). So I conclude that freewheeling can charge the battery. And the more speed you run in freewheel, higher the generated current is. So it would be interesting to do a test by pushing the board only or go downhill as freewheeling (a slight slope for security, of course !). What do you think about this ?

this completely makes sense

I love that you are doing this! Would you be willing to put links to all of the parts on this RU-vid video for the second board you tested? I'd really like to purchase these pieces individually and start a project of my own. Thanks so much keep posting! We're all learning a lot from you.

Boosted Boards regen breaking works a lot better. IF you used 12-15% going up a hill you could get back 6-9% breaking going back down, the board will beep at you when you full charged. this happens if you go down big hills with close to a full battery. Been riding eSkates for a few years and Boosted is the Apple of eBoards its a very nice product.

Regenerative Braking isn't about recharging your batteries at all! The alternative to regenerative braking is to drain your batteries even faster by supplying the motors with reverse polarity voltage in order to stop just like electric rc cars do! Most large scale electric Rc cars actually use mechanical brakes in order to preserve battery life so none is drained by braking. The Regenerative braking simply uses the resistance of the batteries to apply a load to the motors which are now acing as generators, there just happens to be a convenient byproduct and that is a very small voltage increase to your batteries. People often get upset that their re-gen braking doesn't charge up their board much but in reality, if re-gen braking was super efficient and charged as fast as you could discharge, there would be multiple cases of people going down hills with nearly charged batteries and either overcharging and ruining their batteries, or possibly the system shutting down/frying from over voltage and then you'd find yourself mid way down a very steep hill with no brakes at all. You Should do another video on the same hill comparing traditional reverse polarity braking by re programming your vesc (if possible) to non Re-gen and see how big of a voltage drop that is by time you get all the way down the hill! Then compare the percentages of battery loss with traditional electric braking to the % of battery gain with Re-gen and I bet you'll see a huge change in perspective on how efficient re-gen brakes really are.

Science! Oren, this was an awesome video! I wish I thought of it! So valuable. Keep it up! - Neil

If you can change your brake power, put it on least resistance. You cruise downhill lots faster and you get the rpm's to actually regenerate faster. I use this feature about on my teamgee H5. It does work. Just find a sweet spot. I've added 30 minutes to my rides easily by understanding how it works.

For the motors to regenerate energy, they have to turn due to momentum to act as generators. If you had bombed down the hill and then rapidly came to a stop, you would get SIGNIFICANTLY greater battery regeneration as a result of the motors not using much of the power they create on the way down.

On my scooters I don't even care if regen saves battery, im more in it for saving my brake pads. I dont usually have to squeeze down hard enough to engage the pads til under 10 mph.

So I’d assume that the breaking turns the kinetic energy of the motors spinning through the magnets. Faredays principle. So actually just cruising and or barely braking at all would give you back the most since the engine is spinning faster at top speeds therefore creating more current that can be harvested.

Great experiment, I was always wondering the same thing. You answered all of my questions.

You are definitely going too slow to use regen. Regeneration can only happen when the motor is rotating fast enough to produce a voltage of higher than the battery voltage. The type of braking you were using was simply shorting the motor phases together, and using the resistance of the motor windings to dissipate the power.

Customer: Regenerative Braking is bull sh** to use, I just keep stopping and nothing happend. Electric Skateboard expert: You don't know how to use them, you are suppose to brake slowly down the hill and not keep on instant braking.

Thank you for doing research on this topic

Driving a Renault Zoe up and down the Austrian Alps I was able to Regen about 33% of the energy spent. This made a 300km range possible whereas on a highway with constant (and somewhat higher average) speed I only got a 200km range because I couldn't regen much. Regen is not a fluke and actually convinced me of the superiority of electric drivetrains

Great work as usual, Oren!

There are significant hills where I live and I notice a difference when using regenerative breaking. It’s not huge but sometimes it’s enough to fill an entire battery bar on the board.

Sorry man, but you miss a great point. the REGENBREAKING works much better if you not break.. sounds a lite strange i know.. but the Regen do not recovery more energy based in how much you slow down.. but actualy works better if you spin the motor as fast as you can without using the battery energy.. try a 3º time.. and this time go down hill, and do not accelerate or brake, only cruse down hill but without acceleration.. Do this and you will see the board recovery a LOT more energy..

what surprise. i was thinking about this topic one day before you upload the video. nice video. you forgot to mention just one minor thing that i am curious. in the second test, did the batteries/motor get warm?

The voltage has to be higher than the battery voltage in order to recharge it. The only way to produce that voltage is to go top speed when you start braking. Or, if the battery is dead, perhaps half speed, but still, you're looking at like 15+ mph in that case.

When you pass a magnet over a coil, that coil inevitably produces current, and that current has to go somewhere. It can either fry your electronics, or it can charge your battery.

nice test i was going to say do test two n u did just that...my man!!!

Do you have a Xiaomi M365? How high is here the regeneration?

Maybe the ESC just shorts the motor when fully breaking. Then the 0,080% of battery charge could be explained by the fact that batteries lose voltage due to the internal resistance when discharged.

brilliant vid. very helpful info

Very insightful analysis

Nice video my man. quality info as usual.

im not sure how safe or possible it is but high speed and slamming the brakes should generate more power to be store back into the battery, like push starting a vehichle with a clutch

6:34 Motor min (regen) setting is limited to the Batt min (regen) setting. Your 5.2Ah 6-S LiPo has a charge rate of 5C, which makes for a max charge current of 26A. You could probably safely increase your Batt min (regen) value to -20.00A and see if it feeds more current back to the battery (you'll get stronger brakes, too, so be careful), since regenerative braking is essentially fast-charging. BTW: the 10C rating of your LiPo is probably the reason why the fishtail board has less oomph when climbing hills, and the resulting stress on the battery creates heat. C-rating is often exaggerated by the manufacturer and in reality could be less. I recently bought a pair of Turnigy 4Ah 25C batteries to replace a similar 30C variant (the 30C was out of stock), and the mild decrease in acceleration and hill climbing was noticeable, as was the heat generated by the battery pack. The advantage of the 25C variant, however, is the 5C charge rate vs the 2C charge rate of the 30C model (I can finally have more braking power, especially from high speed). As always, experiment carefully and wear a helmet (I want to see a lot more videos from you).

This was a very informative video. Thank you.

That blue rolls at 3:12 tho

I'm not sure how you can tune the regen braking exactly, but I'm curious what the optimal braking is. Seeing as how one was better than the other (light braking at higher speed is better than heavy braking at low speed), then there is very likely some in-between that is even better. Or perhaps allowing time to build speed and then heavy braking, alternating your speed. I'm also curious how aerodynamics (as silly as it is on a skateboard) can benefit the energy lost. What happens if you crouch down or even plank on it (LOL, but seriously)?

I’m pretty sure the point is your cruising around town and have to make a quick brake or brake when in an intersection or gonna make a turn.

I'm gonna take you back a few years to try to explain this, so bear with me. Back before ESCs were used to control DC motors we used variable resistors. This was a length of high resistance wire, rapped around a form in a spiral, with a sliding contacter that completed the circuit. Battery power was fed into one end of the resistor and picked up by the contacter. The closer the contacter was to the source end of the resistor, the more current would flow to the motor. My first experience with this was in the late 70s with a Radio Control race car, an Associated Electric RC12E. I give this history lesson because this power setup also included something called "Dynamic Braking". You see, the resister had TWO winds on it. One fed battery power to the motor, the other fed any current coming FROM the motor, back to it. Basically, shorting the motor leads through a variable resistor. Why do I bring this up? Well, ESCs just use a power MOSFET in place of a wire-wound resister to control current. Our old RC car setups pitted the motor against itself for braking. Regenerative braking tries to use the battery's current as an opposing resistance, but you run into problems. If the current coming from the motor isn't under enough voltage to charge the battery, then you basically just turn it all into heat. That's why the partial braking worked better. Higher speeds equal higher voltages going to the battery. You'll never get as much back as you put out. Losses to heat through the motors, wires and ESCs will consume most of it. Eventually, if you keep testing your braking at higher and higher speeds, you'll hit a point where the amount you get back starts to drop off again. I'm going to suggest that you put an ammeter in-line between the battery and ESCs. That will give you a better idea of the actual current being used and pushed back to the battery.

dope test, thnx for making

Have you tried swapping the hub motors on these boards and seeing the results? I think those nice black hub motors would run better with the VESCs.

For LiPo you need to count coulomb to estimate state-of-charge. Voltage isn't very accurate you can have large range voltages for the same state-of-charge depending on discharge rate, temperature, charging or discharging.

Damn. I was hoping that when I get my first board it would be okay with the hills from regenerative breaking. After reading some other comments though I feel like if I was able to go down a hill at maybe 20/25mph I would gain a lot more electric from little breaking and higher speeds

THANK YOU for doing this experiment. I honestly wasn't sure if you had to break for the motors to generate power back into the batteries or not. Perhaps they could design it to generate on coasting? I use dynamic breaking at work, but we use a resistor to slow down the motors.... The more resistance the slower the motor turns, and why I thought hard breaking would generate more power. You answered another question for me, does it generate MORE when you break harder, That was my assumption and obviously I was wrong. Now you have me curious where the sweet spot is, ultra light breaking or moderate braking for the max poser generated back to the batteries. If its light breaking, and as you said can be up to 25% regenerated, that could be substantial to extending distance, especially if its electronically and automatically controlled.

Meepo has a % charge meter built in. I'll have to read it at the top and bottom of the big hill I ride.

Thank you for doing this

Oren can you tell me what is your experience with this Vesc maytech? still working great ?

Hi there! Great video and thanks for the fun info. Could you try to let the skateboard build some speed (no braking), then brake down to 10mph (brake as long as possible with a steady increase until you reach 10mph),then repeat until you’re back at the starting line.

Very nice video! Thanks a lot!

Hey, the VESC have a bluetooth app that you can monitor many things on the skateboard. include check the Voltage and current draw from the battery. you will need a cable and a HC06 bluetooth module and is just conect to the VESC...

I have the verreal V1 electric skateboard I got it Friday and have been writing it since Sunday and have only lost one bar maybe you should try this test on the V1 thank you your video was very informative

main point of the feature is to be able to still brake going down hill even if the batteries are pretty much flat

Honestly found this out of curiosity as to whether e-boards had braking of any sort(figured regen braking was likely). Even just for the ability to brake it seems nice for long and/or steep hills...I'm thinking the likes that some insane kids go down on regular longboards with little to no protection risking possibly their life or at least horrible road rash and broken bones.

The method you used to check charge percentage makes me sceptic about the results. However, in many ESC full breaking means shorting the motor leads which means that all of the energy becomes heat

Nice video. I was curious how effective regen breaking actually was. I owned a Honda Insight a few back, and it actually did make a decent difference.

Technicaly speeking you dont need to full brake all the time. Better will be if you speed up and then brake with highest speed. this kind of breaking have to give you best efficiency. This is because with highest speed generates higher voltage and efficiency of DC-DC BUST converter is also higher in this case.

The percentages you state are not calculated correctly. You've calculated the percentages based on the overall voltage of the battery, when it should have been based on the 0-100% voltage range of the battery. Example - 10S pack would be 42v @ 100% and 36v @ 0%, meaning the percentage of charge/discharge should be calculated by dividing the voltage change by the 6V range of the pack... You also need to account for the discharge curve of the lipo pack as the majority of the capacity (80-90%) sits between 3.8v and 4.0v per cell on a lipo. This means that if you charge from 39v (3.9v/cell) to 40V (4.0v/cell), you've charged 40%-45% of the pack - but charging from 40V (4.0v/cell) to 42v (4.2v/cell) only means you've added around 10% to the capacity. If we work off of 80% of the capacity of the pack between 3.8 and 4.0v and calculate the charge increase of 0.032v, the math would be *(Voltage Change within 80% band/voltage band size) x 80%).* So in this case: *(0.032v/(40-38v range))x(80/100)) = 0.0128* or *1.28%*

You have to just kick push the board. By breaking down the hill you are using energy from the battery and slowing down at the same time. If you just let gravity do all the work your board will be recharged a noticeable difference. I've recharged my meepo board by kick pushing up to 25% before. Edit: I'm no expert on this but I've tested it before myself

Great info, thanks for this. On some (or all?) boards with regen braking, braking doesn’t work when the battery is fully charged to prevent overcharging. So I’ve had situations where the brakes didn’t work even on a flat surface because the battery was at a full charge. But how’s that even possible if more energy is always lost vs regained (e.g., full battery, flat surface, accelerate for 15 seconds, can’t brake)?

cool test. Looks like sharp stops will gain the most battery life, not one long break

Nice job .. well done.

Should i keep the mode on weak or strong on a scooter?

thus not totally comprehended those Electronic-related mechanics, I've just plainly basic for the scientific EV Circuits to cope with future rechargeable renews

You sure you even have regenerative breaking on these boards?

I live with some pretty steep hills. You think I can rely on regen breaking to slow down and stop? Or should I get a hardware break?

Nice work I hope you make more videos

I wonder if you tested going up hill and down hill on the same speed. Because regenerative breaking on ESC gets very efficient when it hits the motor rpm sweet spot.

how do you even "do" regenerative breaking?

I once rode my backfire G2t to the city, losing about 25 or 30 percent of my battery on the way there. Then my friends took me by car to a very steep hill, so I naturaly went back down on my longboard again and got it back to 100%. I was really suprised just how well it worked. On the other hand, once I rode fully charged board down different hill and it started "overcharging", locking the brakes down completely. So it can be a downside too. I thought it broke it lol.

If you go faster and smash on the breaks it should do a bit more as you will gain more momentum from gravity which in return can be converted to electrical energy, because gravity is 9.8ms^2 Allowing the board to roll longer rather than preventing it the whole time would increase the resistance required to slow down the board.

He just proved that the budget model is better

Have you heard of magnetic levitation instead of bearings.

Great video

seems like it's taken advantage of as a selling point. Despite this, I would still look for this in an ESC because I would rather gain some amount of energy when braking than spending it.

You videos are great!

Regenerative braking are literally the brakes. Any charge the battery receives is what's left over. You need to look up what regenerative braking is lol

Wow looks like you're right near my house near Lacosta. but anyway the guy who used the regenerative brakes the best was heading down very steep hills very quickly then would throw on the break so that there was a lot of momentum going into that regeneration. Lagging down a hill at 3 miles an hour I don't think is going to do it. Try a retest with going very quickly braking for a half a block getting up some more speed do it like that and you'll get way more... good job on the video keep putting out more videos I think I'll subscribe

If that type of breaking is the same is charging, it is shortening the batteries charge lifetime

I am wondering if it would make a difference to go downhill faster breaking only partially.

Running it dead then going downhill may be a good test

It captures the kinetic energy and stores it as potential energy*

A better test would be how standard controllers report said battery increase. I think you find most fake it. Teamgee defiantly does

WHAT THE HELL DOES THIS GUY THINK IS CAUSING THE BRAKES TO WORK < THE FUCKING BATTERYS , he even says in the video the brakes may be using some of the battery. im not sure but i guess u have to hold the brakes to regenerate but appplying a lot of brake seems to use some battery power which makes sense, there should be a regen mode for going down hill or something. i cant beleive what an improvement the second attempt made and it was actually way more effective then i thought

what if downhill without braking, will there be regen energy

The BLDC motors are very low induction. At best they generate a couple of volts, not really enough to recharge a 4 volt cell. The power is pretty much dissipated even if anything of value in generated. The answer would be to have a voltage regulated Buck Boost converter that takes any power and converts it to charging voltage no matter the speed of the motor. You probably find with something that the full braking might actually charge equally to the partial. One way generates a lot of current at low voltage and the other generates a higher voltage. I guess as Americans we should sit around and wait for the Chinese to come up with that, because thats the patriotic thing to do.

Thanks for that test, I put if OFF no need to damage Motor / Batterie for that low effort :)

Do you use a bms for discharge?

You cant measure the energy by just measuring the voltage.

I have a question what's more efficient, Hub or belt driven Motors?

I want to do the long board build the only problem i have is the type of batteries to use

how much do you weigh ?

YOu need speed to get energy back if you dont have speed from where shud the energy come from=== I often overcharge my board cuz I accel realy hard and brake hard but not too hard let it roll you feel yourbodyweight getting into ground nice feeling..if you have to brake alot in your rides is a realy big help..I get a few km of range exstra..need to brake hard often for cyclist,hard turns and scooters people too.

what were the temperatures in the second test?

Thank you good to know, my fat ass drains all battery up hill lol

When you hawe full charget batery regen cant by so efectiw . When you do this whith meaby half capacitat I thing the regen whud be bedr.

you are comparing btween lipo vs lion so it's not that accurate. and like other says ur going too slow as well. in my personal testing in total distance it adds up to 8-10 percent of battery back, it was it test tho, I think this feature is more useful as "smoother brake" tather than increasing the distance.

You sound like a character from a great cartoon out now. Steven Universe. There is a guy named Sour Cream in that show. He is you and you is he.