hey everybody welcome back to Auto scholar with Mr B I'm Mr B and today we are learning about regenerative braking so uh the system that I'm going to be teaching today is most relative to the Toyota hybrid system or the Synergy drive system but it will apply to other hybrids and also with electric vehicles regenerative braking is not very complicated but it is something that you need to learn if you're wanting to know more about these vehicles and of course apply that to repairing these vehicles so I do have my ct200h right here which has the Prius drivetrain in it I also have a couple of trainers that we're going to learn on today I'm going to take you all the way through uh from from A to Z on regenerative braking so let's go inside let's go to my board and start learning one of the biggest advantages of electric vehicles and hybrid electric vehicles are the advantage of being able to recapture some of the energy that it expends by moving forward so this we do a lot with regenerating of the brakes so basically what we do is we take the motors that are in our system and we turn them into generators and I'll explain a little bit about more of that later but the Toyota system that we're using in most of Toyota's hybrid vehicles are going to be 60 to 70 percent efficient at regenerating the energy that is lost so in other words just to show you on the board here if we have two Hills okay we have two large Hills and we have two vehicles one being a gas vehicle one being a hybrid vehicle and we go up these Hills with the gas vehicle okay and at the bottom of the hill I am at a full tank of gas and at the very top of the hill I am at empty so we are at full to empty so after that if I take the car and I roll it back down to the bottom of the hill I still don't have any gas in the car I can't go anywhere I'm not recapturing any energy that I've expended getting up this hill now if we use a hybrid system or even a lot of electric vehicles will do this as well if we go up this hill and we use we have a hundred percent of our battery at the top and we have zero percent uh if we have a hundred percent at the bottom and then we have zero percent of the top in other words we've used every bit of the battery power that we have getting up this hill if I turn the car back around and go back down this hill I will have 60 to 70 percent of the battery uh available charged so I can keep on going through my day so in other words in a gasoline vehicle when I use this energy it's gone it's turned to heat and the cooling system you know will chaperone it out into the atmosphere where this when I come back down this hill I'm turning my Motors into generators I'm regenering the power that I use to get up that hill as I'm coming down the hill it's almost like if you've uh ever been walking and you're getting kind of tired getting up the hill right and then when you walk back you're going down the hill and you're like oh this is so much better well hybrid vehicles and electric vehicles will do that as well and the also another good thing about this is when I'm using regenerative braking I'm not using my regular braking system which this is why on like just the standard Toyota Prius the brake pads will last a very long time so torque news just did a survey on that and they say that 80 percent of people that own a Toyota Prius normally replace their brake pads past a hundred thousand miles okay and 20 percent of those owners it actually takes 200 000 miles to wear out the brake pads to need replacement so as I'm using my regeneration and I'm not using my regular brake system I'm having less wear and tear on that brake system which of course gets me a drop in maintenance cost now there are some downsides to regenerative braking so just like I can't take a tiny small motor and power a car with it uh generators just like motors have limits okay so the Regeneration is limited to a couple of things one being brake command in other words I'm how hard I press the brakes is going to to determine whether I'm using regen or I'm using my traditional brake system so also battery charge is going to be uh affect that almost you know exclusively so if I have if I'm going down this hill and I happen to have a 100 battery and I'm driving down the hill and I'm kind of breaking or coasting down the hill if I have a 100 battery I'm going to be using my brakes almost exclusively the main reason is I can't fit anymore in my battery so if I'm already at the 100 charge on a battery I can't put any more in it also of course I'm limited to the torque of that generator and how much drag it can produce so that's just something to think about again how regenerative braking works and how we recapture power of course we can't recapture power at a hundred percent that's physically impossible but 60 to 70 percent is actually a pretty good return on recapturing the power that we use in a hybrid vehicle okay so I have my console lab trainer this electric trainer that I use with my students and basically what I've done is I've taken this has a a permanent magnet electric motor in here and what I've done is I've just wired it up you know power to a switch and to ground and when I turn this on my electric motor is going to turn so let's just act as if this is a car that's starting out and we're driving and we're using the electric battery to drive this motor now uh you know I'm depleting power from the battery and there is a way to get this back so as this is turning remember that you have all this kinetic energy balled up in this car and it's moving down the road and now when we go to put on our brakes if we use regenerative braking we can take some of that power and put it back into the battery so we can use at a later time so I'm gonna go ahead and switch this off I'm going to take this right here we're going to wire this up to this led and we're going to act as if the LED is the battery on the vehicle so when this LED lights up it is if the battery is getting charged so we take this magnet and we spin it so we're not adding power to it anymore and we're taking this and we're spinning this as if the car is slowing down okay and so now this has some drag on it okay this isn't that very easy to turn and that drag is the magnetic resistance inside that motor but what that does is when the rotor and the stator you know when this when the rotor spins inside the stator it induces a voltage that goes into this LED and lights it up so this is how the motor generators work in almost every hybrid and electric vehicle on the market so let's go out here to our gen 3 Prius trainer and I'll show you the motor generators okay so this is my hybrid trainer here from console lab great company and this is their uh gen 3 trainer so it has a cutaway of the transmission that shows the motor generator one and two very well so this is your motor generator one right here it's the larger of the two and it is does the brunt of the region or to breaking and this is your mg2 it does play a role as well but as you can see mg2 is just way bigger than mg1 is mg1 acts more as an alternator and a starter when the engine is running also remember on this vehicle we can use engine braking so we have a dampener here and that's the piece that you see that's spinning in here and that dampener can hold the engine and we can use the engine's compression as an aid to braking on the vehicle just like any other vehicle with a manual or automatic transmission using engine braking this works the same so when we put our foot on the brakes there's a lot of decisions that are actually being made technically the driver doesn't have any mechanical input to the braking system so we have a brake actuator mounted on our firewall and it gets the signal that the driver wants the car to break so not only does it get the signal it will tell uh the through the communication system it'll tell other control modules how hard I am braking so this is the module here that is inside your brake actuator and it has you know this valving here and that since the brake fluid where it's supposed to go but also we talk to the battery control module because like I said before we have to know how much charge the battery has so we know how much regen energy we can put back into the battery if the battery is too full the battery control module will signal to the ABS module hey I can't fit any more power in me you're going to have to use your regular brakes and the car will use the regular brake pads and rotors uh the friction brakes to stop the car also at a certain mile per hour it doesn't make sense to use regen so we will use regular brake pads and also regen does not work in an ABS event okay so just keep that in mind moving forward that uh the majority of the breaking done just in normal everyday driving is done by the region and this is why the brake pads last so long because they're not being used as much as would be on a normal car you know normal car 40 50 000 miles you need brake pads maybe even sooner on these cars 100 000 miles is pretty much the normal and I've seen them go a lot longer than that mostly I see them around 150 to 175 000 miles needing brakes but again we're taking this power and we're putting it back through these orange cables now these are AC Motors and AC generators we're we are using AC current and we're generating AC current of course the battery works off of direct current so we have to take all this power and we have to turn it into DC powder and we use the inverter up here to do that and what that does is it flips it around the ac voltage and it turns it into Direct current and then of course we just main line that back to the battery which is represented here and the battery is going to of course tell the battery control module you know how much power it has and if it is available for regen so uh if you've ever put on your brakes kind of hard and you feel like the brakes kind of slide into a a tougher brake or a harder break that's because the the brake module saying okay we need to use our actual brake pads and so you'll get a little bit different feel as the brake pads activate versus the regen but this is also why the brakes on this car are so touchy and if you've come from a conventional vehicle into a Toyota hybrid you'll you'll have about a week to two weeks of really adjusting to the brake feel on these cars because they are so touchy so yeah mg 2 mg1 and again mg2 is is bolted uh to a uh planetary gear set that goes directly out to the uh main drive on these vehicles and so this is the one that does the majority of the regenerative braking and it's so big that's why you know you have these huge magnets in there that will provide that resistance and that's what gives that braking effect and it also what gives it that induction and allows it to generate power so as you can see we're just moving under electric power right now and I'm driving about 15 miles per hour the engine just kicked on I'm going up a little bit of a hill here but as I let off when I'm coasting the car is going to put power back into the battery through the motor generators you can also see this on the charge gauge as I accelerate when I let off you see that dips into charge and when I put my foot on the brakes that'll go deeper into that charge and what that's doing is it's using those motor generators to put drag on the axles which will charge the battery well thanks so much for joining me today on this lesson on regenerative braking again if you have any questions please leave them down in the comments I try to answer the questions in my comments at least once a day across all videos on the platform so I am on YouTube at Auto scholar Mr B here's my page here don't forget to like this video If it taught you anything in the course hit that subscribe button for more lessons on hybrid vehicles I'm gonna be adding a lot more stuff I'm also going to be adding some EV stuff as we prepare to start teaching this to my students so I'm also on Facebook Instagram Twitter VK if you're in Eastern Europe follow me over there on Auto scholar Mr B or Master Tech Mr B so thank you for joining me I hope you have a great day we'll see you next time on auto scholar with Mr B