hey guys Micah here from ebike school calm and today we've got another Q&A video this time the question is coming from Jonathan overs asking how do you do regen on electric bicycle thanks Jonathan for the question you guys remember how my Q&A videos work you asked your questions in the comments below I will choose questions every now and again and whoever I choose to make a video response I will send you a copy of either my first book the ultimate do-it-yourself evite guide or my second book DIY lithium batteries this one actually has a lot of information about regen braking as well but we're gonna go over the topic now so you can learn it this way thanks to the question Jonathan and I hope that I address all of your different questions here alright now first of all us is regenerative braking possible on an electric bicycle the answer is definitely yes there are a lot of e bikes out there with regenerative braking but you do need the right components to make it work it's not possible on every bike you have to have the right parts so first of all you have to have the right type of motor the only motor that can really be used for regenerative braking is a direct drive hub motor so those are the big ones they're usually black but they're you know the bigger non geared motors you can't use these little geared motors because there's a clutch in here and they're not directly driven when you're going forward these motors Coast so you have no resistance that's why those big motors you know like the nine continents and the crystallite motors the magic files you know the big motors that they don't have any gears they're able to regenerate electricity because you're basically driving them forward instead of letting the motor drive you when you coast you're you're powering the motor you're pushing it the opposite way or when you go to break and use regenerative braking you're actually engaging the motor and that's sending electricity back out the opposite way to charge your battery the other thing is that you cannot use a mid drive system to do regenerative braking so if you have you know a BBS o2 or BBS HD or the other you know popular mid drives that are out there that's not going to work either because again these freewheel this time it actually uses the freewheel on your rear bicycle wheel but either way you're not driving the motor when you're using either these little geared hub motors when you're using a mid Drive so you need a gearless direct drive hub motor next you need some way to engage three breaking the most common way is to use what are called ebrake or electronic brake levers that often come on e bikes or they come with ebike kits these function mechanically just like a normal brake lever but they also have a little micro switch in there and a couple of wires so when you pull the lever the micro switch closes and it lets the circuit know whatever it's connected to that you've just pulled the brake lever the other option is to use some type of momentary contact switch this is often a button on a throttle or you can just get a stand-alone button that goes on your handlebars but you need some type of button or switch to engage the regenerative braking the last thing you're going to need is a controller that also has a regenerative braking option not every controller can do regen braking in fact I would say probably most of the cheap ones cannot do regen braking it has to be at a controller that has this enabled and there's no real easy way to just look at a controller and tell you can't just look at it and say oh this one definitely has it it needs to be listed on the spec sheet or you can ask the vendor but make sure you're actually getting a controller that can do regen braking if that's something you're looking for now the way that you connect all this together is really simple basically any controller that's going to have a regenerative braking option is going to have some connector on it somewhere it's almost always a to wire connector and you're just gonna plug that straight into the 2 wire connector on either your ebrake levers or your momentary contact switch on your throttle or any other momentary contact switch the wire color can basically be anything that's gonna be red and blue black and white like an orange you know red and white I'll just every color combination out there there's no standard for regen braking so you just have to figure out or ask your vendor which connector on your controller is meant for regen braking and you plug that into the connector on your ebrake sore your momentary contact switch there are some controllers out there that are programmable so you can actually connect those to your computer and then you can edit some of the settings you can increase the power of the regen braking and you can change some of the different settings there how quickly and engages etc but for the simple controllers you basically just plug in your brake lever or your momentary contact switch and then anytime you pull the lever or press the button you're going to start regenerative braking now how efficient is regenerative braking on bicycles and this is sort of the issue that that I've had a bit of a problem with because I found that regen braking just is that efficient on electric bicycles you know you seed a lot of electric cars but cars are much heavier they have a lot of momentum and I think it's easier to you know pull that energy back out when you've got so much kinetic energy moving that you can convert back using the regenerative brakes but on electric bicycles the best that I've been able to do the absolute best on one trip I ever did was I think about eight percent of the energy that I had an eight percent return of the energy that I used so for example if I used 10 amp hours I got back about 0.8 amp hours generally I averaged closer to five when I was in us 5% when I was in a city setting so you know if I'm doing a 10 amp hour trip I got back a half an amp hour or for a 20 mile trip I got back one mile of extra range because of that regenerative braking and that was when I lived in Pittsburgh which is you know a city with a lot of stop and go traffic a lot of you know red light stop signs that sort of thing when I've done longer trips that are just you know on like long open roads where I'm driving for a long time I've had regen percentages like one or two percent because if you're not braking often you're not going to be using your regen a lot so what I found is that regenerative braking it's a lot more efficient if you're living in like a city where you're doing a lot of stop and go but if you're out you know in the suburbs you have a really long commute with long straight sections you're just not going to get that much return for the regenerative braking now that's not really a problem you know like a free five percent or a free three percent extra range you know that's great it doesn't really cost you anything but don't expect it to you know just be this like magical boost on your range because it's not going to make a huge difference and like I said I think a big part of it is just the weight you know when you weigh more than your vehicle there's just not that much momentum there to convert back into into energy for your battery now there are a couple of concerns that you do need to worry about when you're deciding to go through generator of braking the first one is going to be the way that it charges your battery so regenerative braking almost always charges your battery back through the discharged leads and this is certainly possible you know if your battery is a BMS then the sort of avenue that power flows out of your battery through the discharge leads is able to handle a lot more current than the Avenue the that power flows into your battery through the charge leads so you can actually charge through the discharge you know you're not really gonna be worried about blowing anything or burning anything out except for one specific scenario which is important to discuss and this is sort of like an odd you know unique case but consider this imagine if you lived on the top of a very big hill or that's where you were starting your trip and you just charged your battery up to a hundred percent so now you start going you're not using any gas because you're on top of a hill and you just go downhill for a long ways while using regenerative brakes so now you're pumping charge back into your battery but you're already at a hundred percent so you know if this goes on for a few minutes you can get up to you know 100 100 to 3% and you're suddenly starting to overcharge your battery now you can't actually overcharge your lithium battery you can get it up to you know 105 percent or so of what it's meant to charge going too much over that can be dangerous so you really don't want to overcharge your battery if it's just a little bit all you're really doing is decreasing the health of your battery but if you overcharge it too much it becomes a very dangerous situation and you risk you know fire explosion all sorts of bad things so that's sort of a very specific scenario where someone starts at the top of a hill with a fully charged battery and regenerative brakes all the way down it's not going to be a common scenario but it is important to consider just in case this is something that you could run into the other important thing to consider is a torque arm for your motor now if you are using regenerative brakes what that means is that in addition to the normal force that you're having turning the axle one way when you accelerate suddenly when you do regenerative braking your axle is going to be forced to turn the other way because now you're powering your motor backwards and so it's a really good idea to at least have one torque arm installed holding the axle of your hub motor you know if you don't know the torque arm is look it up they're really important to hold onto the axles for higher power ebikes below like 500 watts or so they're not super important once you get above 500 750 they become very important but if you're doing regen braking they're even more important because now you're forcing your axle forwards and backwards forwards and backwards all the time and this can allow it to start loosening up at the nuts and you could actually have your axle slip right out of your bike so if you do regen make sure you look into a good torque arm I really like the ones from e bikes that CA but you know there's tons of different designs out there and every bike shaped a little different so you got to look around it at different ones but those are the most important aspects to regenerative braking definitely possible probably not as efficient as he would hoped it would be but you know it might be a good thing for your bike if you can get an extra one amp hour for every 20 amp hours are used why not all right thank you for the question Jonathan make sure you send me a message here on youtube to let me know which one of my books you'd like and let me know your address I'll send it out all right now it's time for our weekly book giveaway remember for this one all you have to do is comment below this video you know you can leave a question if you want me to answer a question hopefully I'll choose it for a video in the future or you can just say hi but leave some comment and I will choose a random commenter to win one of my two books and this week's commenter was I have it somewhere Matt Barnard this week's winner was Matt Barnard who liked my video almost as much as another interesting crowd control video so thank you very much for Matt remember I'll choose a randomly chosen winner from comments on this video to win a book in my next video all right thanks for watching everybody I hope you enjoyed this video and I hope it taught you a little bit more about regenerative braking see you next time