Prius "B" Mode Explained

[@thatcarguy1UZ]

The “B” setting allows the drive motor to continue to produce reverse torque by being used as a generator, and the electricity generated is used to drive the engine via the motor alternator. This effectively allows the engine to be used as a brake and regulate vehicle speed. The engine is spun at high speed with no fuel being injected, using it as an air pump to dissipate the momentum of the vehicle. It will also charge the battery but when you run out of capacity to charge because the battery is full, it will use the engine to dissipate energy. The engine kept running and didn’t go into EV mode right away because it cooled down by processing air without combustion. If you were driving down a long steep grade in “D” the car will fill the batteries up to 100% and then you will be using friction brakes which can overheat if the grade is long and steep.

[@bennri]

It's basically the same as L gear. B stands for Engine Braking. If the battery isn't fully charged, it charges the battery too.

[@ibeatmycatandmydog9322]

So should I use b instead of braking when possible

[@thatcarguy1UZ]

@@ibeatmycatandmydog9322 Not normally. Most braking is still done by recharging your batteries in the normal driving mode. If you are in the mountains or a long very steep hill then it would be useful, just like using low gear to descend a steep grade on a conventional car. In B mode the generators charge the batteries but also “waste” energy by spinning the engine with the fuel turned off and using it as an air pump for “compression braking” to save wear and more importantly heat buildup in your brakes. This is not necessary in normal conditions.

[@thatcarguy1UZ]

@Andrew H No, your battery will recharge faster with regular regenerative braking. However, as stated previously, if you are descending a long steep grade, the B mode will consume extra energy by spinning the engine in order to slow your descent down a long hill. If you use this function in normal driving, some of the energy that could go to your batteries will instead go to turning the engine when turning the engine is not needed. The only time this would be advantageous is on a long hill descent where the battery will recharge to over 80% before you reach the bottom of the hill. In this case turning the engine as a dynamic braking load instead of engaging the friction brakes will allow you to control your descent speed without overheating the brakes.

[@UmmYeahOk]

@@thatcarguy1UZ so how does “b mode” work in full EVs? (Not hybrids). I have this exact shifter in a 2014 RAV4 EV, and have accidentally driven miles with B mode engaged not knowing anything other than the fact that the cruise control won’t work. Took me several months to connect the two. It doesn’t seem to brake much. After discovering what it really was, I tried to use it like I would with the Chevy Volt, and apply it when stopping.

[@Driver6M]

A lot of manufactures have a CVT transmission but the transmission in the Prius is a completely different design. There is no belts, it's a variable transmission based on planetary gears with the ratio being changed by the difference in speed of the Prius' separate electric motors which drive different parts of the gearset. It's a fascinating piece of technology.

[@jettlash1000]

Thank you for the detail on this!

[@130rapid]

Indeed, no other transmission type has so few moving elements & so much abilities.

[@tinyroomedits606]

🐙🐍🐲🐈

[@Landrew0]

You are correct. Calling it a CVT is a bit misleading, because it is an entirely different design. One gasoline engine, and two electric motors are connected to the drive wheels, through a planetary gear-train which functions like a differential in reverse; When they are pulling in unison, full power is transferred to the wheels, but when the electric motor is running at a different speed to the gas engine, a gearing ratio is achieved, to allow the gas engine to run at more efficient speeds. In fact, "neutral" is never actually neutral, because the motors and engine are never disconnected from the drive-train; the electric motor compensates for the gas engine in whichever direction it needs to turn, to allow no torque to go to the wheels, allowing it to roll.

[@jettlash1000]

Very nice description, thank you for taking the time to provide some more input!

[@jaunquavo5847]

4:14 B mode

[@dipenbhuva2061]

God's man

[@orange_lada2119]

This video could have been 20 seconds long.

[@Orwellwascorrect]

Thank you

[@tediousv1461]

100% and was the “B” ever even defined? I fell asleep. I think it means battery. Fill up battery. Bumps up the idle. Should’ve been the video title

[@GabrielGriffin82]

Thanks for the warning

[@Koover88]

B" mode is also fantastic for snowy downhill driving. It just slowly grips it's way down the road without having to use foot braking which is where most skids start. Getting some good winter tires and using the prius technology to your advantage can make this car VERY good in the winter.

[@waltfromphilly6563]

Thanks for the clarification of the "B" mode. I have a 2007 and always wondered. Bought it new and currently have about 125k on the odometer. Just wondering if the lower glove compartment lamp is normally ON whenever the headlights are on.

[@Areya-Sunshine]

Great to know! The Prius is also quite good on ice in general, even without B mode. My 2016 Prius had its first test on ice last winter when I had to drive on a back road that was a complete sheet of ice. Normally, I would have just glided over it and not turned the wheel, but this road was downhill and curved so I had no choice but to brake and pray. The Prius performed amazingly. Basically the anti-lock braking system kicked in right away when I gently hit the brakes, and it pumped them the whole time we went over the ice. It was nice and smooth (just sounded scary) and I was even able to turn without skidding once. I think the Prius knew to do this because it could sense the tires losing traction and so it pumped the brakes to help regain traction. And I didn't even know I could use B mode to help in snow so I might try that next time!

[@Maximonious]

Just experienced this today. CO is getting a pretty good winter coat.

[@bhaddock9277]

Was a passenger in a Prius on a road freshly covered with snow. Had hard time explaining "B" mode to the driver. I suggested using the "B" mode to trim off excess speed rather than braking, especially while turning. At low speed was all too easy to slide into another vehicle while negotiating through a neighbourhood with narrow roads, random parked cars and changing gradients. Got earfull for being too technical.

[@mr.russerzplace...1448]

And b mode will charge vape pen and prius battery same time!!

[@waltfromphilly6563]

Thanks for explaining the "B" mode. Bought my 2007 Prius new and never used it before. Still on original brakes, Four new tires, couple change outs of wiper blades, three headlamps, and one new battery. Most reliable vehicle (besides my '97 Chevy S 10) I've ever owned.

[@kg4tnp]

MG1 actually spins the engine up during B mode to create drag on the drive train. The engine is not actually producing power, the injectors are off. The main reason not to use B mode during normal driving is it causes the engine to spin and places a electrical load on the system. The hybrid ECU also normally tries to prevent 100% charge as the batteries last longer if not charged all the way to full.

[@joakimspetz7745]

B-mode is an option to waste energy in the form of using the gasengine to compress air. This does helps to slow down the car. The passive regeneration is about 2x as strong in B then in D (no foot on break). So you are charging your battery 2x as much. Problem is that the car is loosing speed from compressing air as it is enginebreaking. This will make you get less total energy into your battery compared to just keeping shifter in D-mode and apply a little pressure on the breakpedal. This way you are only using the rechargegenerator to slow down your car and are able to get maximum charge from the downhill. Note that you should not go to close to maximum on the charge bar. As the bar gets closer to maximum it starts to softly apply frictionbrakes wich lead to heat instead of battery charge. So in ECO standpoint B-mode should be avoided. As others said B-mode is usefull when battery is fully charged and still going downhill and in winter to get some free engineheat from enginebreaking friction to reducing the engine ON-times at redlights and slow speed driving that in summer normally is done in EV mode. Forced engine running is due to heatsettings. Turning heat off will allso turn gasengine off (if engine is 60+ degres celcius). So dont waste kinetic energy with enginebreaking when you have regenerative breakes. Non hybride cars can save brakepads by using enginebreaking.

[@brianmef71]

I like how some people talk a lot thinking they know it all when they don't. 😂

[@joakimspetz7745]

@@brianmef71 Ok, then go ahead and drive with B mode all the time if you think it is the best way to save fuel.

[@ArroyoAirsoft]

Depending on the vehicle's speed and the battery SOC (state of charge), the Prius will do this using regenerative braking and/or high-RPM zero-fuel-flow engine braking. ... Just as you might downshift into 2nd gear when going down a long, steep hill to prevent brake damage, you can "downshift" into "B" mode on a Prius.

[@abyssunderground]

When the battery is full and you say the engine is still running, it's because it can't regen any more energy to the battery so the engine has to take over the braking instead. It's a clever system and has its uses, but I've not had to use B mode myself as my area is fairly flat.

[@cutflow2]

Is it ok to use b mode to slow down on the highway when the traffic up ahead is slowing down or still

[@abyssunderground]

@@cutflow2 It's not desirable, but you can if you want to. Instead you should use regen to slow down and recapture as much energy into the battery as possible for best fuel economy. B mode is for long hill descents not for general stopping.

[@nationofgandhis]

@@cutflow2 does the engine come on with "not full" battery? prime? in B mode?

[@mikeq5807]

I enjoyed the video! I used B mode on a very steep hill in Portland, Maine. It does grab very well, and it did bring me below the speed limit. Great feature!

[@mattwernecke2342]

Thank you! I am an Uber Driver. I just picked up a 2014 Prius 2. The money, that I am saving in gas, pays my note. I had rider today ask me about the B drive.; I had no idea! Thanks so much! Best, Matt

[@johnsolomita1888]

It stands for breakfast

[@usmansidat6471]

😂😂😂

[@mordenmw]

Thanks for posting. this explains it better than the dealership did when i bought one.

[@SabreLeonheart]

Oh man, good stuff brother. I'm the opposite - I drive 99% of the time in PWR Mode. I love how much more fast it can accelerate and I it goes immediately without me having to push down too hard on the pedal.

[@manjotsandhu9539]

I am an uber driver in Seattle bought prius at 0 miles maintaining it since then properly now it's at 170k one problem windshield wiper motor, other than that no problem no engine check light. same engine as yours 1.8l. I use b made going down the hill it charges your battery plus helps you with good mileage. car had plenty of power it can top out 125mph easy. awesome car. The b mode is actually engine braking I don't recommend on very steep hill. With b mode you can always charge your battery 100%. I have been doing it since I have owned it. I still get between 45 to 50 mpg

[@jettlash1000]

That is awesome to hear! I love hearing about the reliability on these cars being so good. That was one of my top reasons for purchasing.

[@robertgarrison5478]

Did you replace the wiper motor

[@readhead12]

I normally never use the B mode. Unless it's very steep. You can just press the brake pedal gentle and it will regen as much as it can. If the battery should get full, the car automaticaly activates the "B" mode, even when you are in drive mode. Because the battery is full it needs the engine to simulate braking.

[@nationofgandhis]

not too sure about auto B mode? mmm

[@danielbaboiu2288]

The effects you see are not unexpected. Usually, the B-mode is interpreted as "extra regenerative mode", but this is wrong. The Toyota manual states that the B-mode "applies engine braking", not "regenerative braking". After some digging, I found that in B-mode the gas engine is coupled to the wheels, like in a regular engine brake, but without being fed with gas; internal friction and air compression act as brake, wasting the energy that can not be regenerated (need more braking than can by applied by regeneration, battery is full, etc.). I don't remember where I read that, but it makes perfect sense with what you observed: 1. Around 5:30, before you shift into B, regenerative braking is quite strong, as seen in multi-info display; dropping in B-mode, while barely gaining any speed, the regeneration gets rather low. 2. You hear the engine being on, but the hybrid display shows that it does not generate energy -- consistent with engine in motion, but not consuming gas (instant MPG is over 100). The B-mode is useful in two cases: 1. You need more braking than can be provided by regenerative braking 2. Your battery is full, but you still need braking; regenerative braking can't store any more electricity. Short version, in B-mode, braking energy is wasted, not regenerated, which is why you are advised not to use it. The guys using it all the time will get worse overall mileage because of this.

[@consumercellc1109]

That's not true, B mode turns the regen on full blast. If you have an app thats monitors your battery you will see how quickly the amperage jumps up and the voltage reaches full charge after just a short time on B mode.

[@Koover88]

"B" mode is also fantastic for snowy downhill driving. It just slowly grips it's way down the road without having to use foot braking which is where most skids start. Getting some good winter tires and using the prius technology to your advantage can make this car VERY good in the winter.

[@JIllMalanga]

I just did Mt Washington in NH in my 2014 Prius. I used B mode on the 8 mile downhill. It is 6,000 ft of elevation and steep. I did have to use the brakes all the way down, pumping rather that riding and stop as often as possible to cool the brakes.They did get warm and smell hot from time to time. I am glad we made it, but probably wont do again.

[@Jay-vw6hn]

I absolutely love the Toyota Prius. Fantastic car.

[@tractorguy1994]

Excuse me what

[@conorburby2083]

@@tractorguy1994 I mean it gets great gas mileage, 2016 doesn’t have horrid control like 2015 and lower. Yeah if u want a fast car then this isn’t for u but u want cheap driving then yea

[@GraemePayne1967Marine]

Thanks for a great video. I use B mode frequently on my 2004 Prius. (I'm the original owner.) Thanks to that and other practices (like trying to coast to a stop at traffic lights) I will be having the brake pads & shoes replaced for the FIRST TIME at the 200,000 mile service interval in a couple of months. * The engine may sound like it's running, but it is not. The vehicle is using the engine compression, without fuel, to help control the speed. It's the same as downshifting in a conventional transmission but keeping your foot off the gas. * My car manual says not to use B mode above 40 mph. Later models may be different. * My father-in-law had a small Farmall tractor from the early 1950s with a CVT transmission. So does my wife's 2003 Saturn Vue.

[@nationofgandhis]

2020 manual..."When the vehicle is driven at high speeds, compared to ordinary gasoline fueled vehicles, the engine braking deceleration is felt less than that of other vehicles. p. 345

[@lin498]

Hi JL. Got my own Prius now and really enjoying it, thanks for all the useful advice you've passed around. BTW, in B Mode going downhill the engine turns over to provide mechanical friction braking without burning any fuel. This is like a typical has engine coasting downhill doesn't use fuel, but the Prius in B Mode will not overcharge the battery from regeneration. I hope this helps you and your many followers to understand the Synergy motor better. Happy Thanksgiving to our American cousins from UK with best wishes for the Holidays.

[@allenfischer6472]

I've had my 2016 Prius for seven months and love it and almost have 30,000 on it now, I do a lot of driving. About 5000 miles a month

[@BlikeNave]

Driving down a slight gradient in B mode as a Prius driver, then seeing your battery charge is one of the best things. Happens all the time. Every time I press on the brakes it feels like I'm making money. Love this car.

[@Hilljoona]

Except the B mode doesn't affect the charge. In fact, it's charging better in D mode, because the combustion engine does not brake the car by using part of the driving force. Moreover, this is perfectly visible in this video. In D the load bar fills up completely, while in B it only goes up to a third. Moral: in B, you brake more and better, but you don't charge the electrics better or faster.

[@BlikeNave]

​@@HilljoonaCorrect, D is the main. I was just expressing my love for driving downhill in B mode, on top of the typical charging gained from rolling around. Also should replace the word "brake" in your moral so people don't get confused, as B as you stated uses the engine to slow the car and not the brakes. :}

[@FishingWithMichaelTruong]

I use B mode on my gen 2 Prius for emergency breaking situations or going down steep hills and needing to apply additional break force.

[@simonsmashup]

It's also good in traffic, save a lot of work to put on the brake.

[@k30v6xxzeapm]

You have 3 means of braking - regen, friction and engine braking. When you use B mode, it not necessarily means that you are regenerating better. Most of time its better to use D-mode and apply brake pedal slightly, as long as the CHG range is not exceeded. B-mode is OK for really steep hills and loaded car. It also automatically uses the B mode, when the battery is full. Tested yesterday when driving downhill from large hill. Of course its stupid to worry about high rpms, its made to do this!

[@rawadhasan9111]

Thanks. Your video helped me understand this 3 year long mystery in my brain.

[@albyyaris2]

While going downhill, the dealer told me to keep driving in D mode. Once your battery is fully charged, you can shift into B mode. Also, they say "B mode" is very useful while driving in the snow ( I guess it's because that helps slow down the car without touching the brake pedal, which is a good thing when you have to deal with icy/snowy roads )..have you ever had the chance to try it?

[@Espr14]

B is to keep friction brakes cool (avoid deforming). So if you're going downhill and the battery is nearly full, use B mode. This happens normally on big hills with fully loaded car.

[@hunterhalo]

the dealer said, the dealer said, the most misleading conception that i always heard people said. listen to this guy he knows what he is talking about, and please read the manual, it will explain to you, and there is no part that said you need to fully charge the battery before engaging B mode.

[@aysennooris2340]

Hi there, Can I shift the gear to B mode while gear is on D and the car is moving?

[@nationofgandhis]

@@aysennooris2340 yes! NO problem, done it many times!

[@danielbaboiu2288]

@@hunterhalo You can engage B-mode any time you drive, but if you do, energy that otherwise be regenerated is wasted as friction in the combustion engine. That's why it is advised to use B-mode only after the battery is full, to maximize regenerative braking.

[@officebear4637]

An interesting thing to note with priuses is that even though they have a lot of engine braking, you need to use the brakes every once in a while because depending on humidity, they can inflate just enough so that the pads rub against the rotors, slowing the car down and eating up a lot of battery and fuel. Happened to my grandpa because he lives near the sea, he started breaking more often and now the problem is gone.

[@jettlash1000]

Good advice!

[@henkgrui]

My Prius 3 was able to charge the whole battery (all lines) in the French mountains. I drove 4000 km in Europe from the Netherlands to the French Pyrenees and back again. Average usage 5.1 liters per 100km, this is not bad in my opinion if you know that on the Highways was the speed was 130km per hour and a lot of steep hills. In the hill's B mode worked perfect but sometimes the engine made a lot of RPM's when it was very steep.

[@simonajbrown]

I had wondered what the B was for, thanks for the explanation.

[@brento2890]

Thank you for all the videos you post. I find it very informative. I drive a 2013 Prius.

[@jettlash1000]

Thank you very much!

[@infernonine]

Thank you just got 2 2018 Prius two cars for me and my wife very informative

[@jettlash1000]

Awesome, enjoy!

[@Itsme_yaGuRL_]

Thank you for sharing this information. I just bought our first prius today. Cool stuff to know

[@oo-dd3lk]

Excellent ! Straight talking, no hype. Thank you.

[@Landrew0]

Let me help by putting this in simpler terms; Normally when a Prius going downhill, coasting and braking are regenerating kinetic energy into electricity by charging the battery. However, when the battery is full, there can be no more regeneration, therefore some other type of drag is required. This could be from the brake-pads, but that can be destructive and wasteful. In a normal vehicle, some engine-braking can be accomplished by not applying the accelerator, and allowing air pressure and friction from the engine to provide some drag. It's no mystery why the Prius engine is running while in B-mode. To provide drag without braking or regeneration, the engine is bleeding off energy by compressing air, when the other two options are not possible or desirable.

[@stargazer7644]

Except that the engine doesn't come on for a while in B mode, and the engine also eventually starts in D mode when using regen down a long hill.

[@lavatrip9344]

So it looks like you're starting to answer my real question. But are you sure that you know what you're talkin about? Are you sure that it's using actual engine compression to help slow you down after the battery is full. I understand the battery can't help slow you down by charging when it's full because it's already full. My gen2 is not really showing me how much regenerative action is happening and I'm having trouble Discerning when the actual brakes are being applied and wasting energy. So if putting it in the B mode increase is regenerative braking when possible can I further increase the regenerative braking by pushing the brake pedal? Or does that max out the regenerative braking simply by letting off the gas pedal?

[@channel_B5]

en.wikibooks.org/wiki/Toyota_Prius/Driving_tricks

[@mikesdav]

It did this in my Ford Escape hybrid in L gear. It is using the 2nd motor to spin the engine to waste some of the excess energy when the battery is full. If the hill was more steep you would hear the engine rev higher. A Tesla does this and has settings to adjust how aggressive it is except it is impossible to do at full charge.

[@GeorgHekt]

I had the super full battery recently as well and initially assumed that not having EV mode at that moment meant a problem with the car. Then I checked the manual and it said that when the battery is showing completely full it means that it is simultaneously running hot. So the car stops using it for a bit in order to cool it off.

[@nationofgandhis]

good point! what year?

[@GeorgHekt]

@@nationofgandhis my Prius is 2009

[@meletispogkas1475]

its not only the transmission that is breaking the car but also the high compression ratio of the prius engine (13:1 rather than 10:1 in a regular otto engine) witch produces a "bigger" vacuum in the cylinders as the pistons are moving downwards.

[@martinbernard1250]

I have a 2020 Prius prime and b mode disabled my cruise control and keeps the engine running while in hybrid mode. The engine never turns off when coasting or when stopped.

[@jettlash1000]

I’m jealous. I’d love the prime! How do you like yours?

[@nationofgandhis]

@@jettlash1000 love mine, though dealer does not use W16 as requested by manual. If W20 oil used change every 5k otherwise 10k. some say heavy acceleration not available w/out engine in EV mode but I have never had that problem when tested... nice electric torque now we have insurance discount for safe driving...

[@kostasg7109]

B-mode is really for continuous hilly terrain like how you find in Europe in mountainous areas. Typically just before reaching the bottom of the hill you gas the car and remove your foot off the gas pedal around half way to allow the momentum and battery power to move you to the top; once at the top of the hill you place the car in B-mode to allow the brakes to charge the batteries much faster in order to repeat the process again at the upcoming hill. Doing so decreases fuel consumption quite a bit in such terrain.

[@Speed74LP]

When going down hill, and you want to charge the battery, you better stay in D and brake several times. Since D Mode retrieves more energy as B Mode. In D Mode only the generator brakes. In B Mode the generator AND the gas engine brakes (you can see that, when you turned into B the green EV Mode light is going black, showing the gas engine running, it needs to run, since in B Mode it brakes too). So when the battery is low level and you go down a hill, better use D Mode and brake more. When the battery is full, you can use B Mode. Either way, D mode is more efficient. But i think the system warns after a period of time, going down hill only in D Mode, that you should go to B Mode so that the car can brake more and the generator doesn't overheat or something.

[@jettlash1000]

I agree!

[@ruimsfreire4919]

MODE B IS ALSO USEFUL WHEN WE LEAVE A HILL AND THE FLOOR IS VERY BROKEN, SO WE DO NOT LOSE REGENERATION

[@qztronic]

You shouldn't go a long decline in D, because as you brake to keep the car in constant speed the battery will constantly be charge as you go and the charging-habit is "as much as possible" in D vs "charge only litely and throw most away( to the engine) " in B. when driving in D, only after a short while the battery will finally get full or overheat (or both) causing the regenerative braking to not be anymore possible, then the car have to call for a special braking mechanism of which B mode use anyway. so by driving in D you will instead end up with a hot battery for no reason in long decline. They put B mode for you to really use when going down hill so I recommend to just trust the system. PS. B mode mechanism explain: because the Toyota's hybrid car always contain atleast two MG-unit (motor/generator unit), B mode produce engine brake by using MG2 as generator creating electricity as you brake (if not back to the battery where can the power go) so they send it back to MG1 to act as a motor to spin the engine, the engine work in engine-brake mode pumping air to create heat (the engine that you here revving when going down hill involved no fuel injection, it rev up just to pump air to create heat loss to use up those excess electricity cheers.

[@dimosk7389]

although it makes sense for fuel economy and battery charging, i would never risk overheating the brakes on a long decline for the sake of battery charging ;)

[@StanTrnik]

Not true, you can't overheat battery with braking in D, you should drive down the hill in D whole time until you fill your battery completely. You should use B mode only if regenerative braking is not enough to slow down the car to speed you wish OR if your battery is fully charged and you want to save brake disks. If you will drive down the hill in D mode for like one hour, there will be no damage/overheating to your battery at all. Also energy created by generator is not used to spin motor in B mode, it's just not connected in to the circuit at all. Combustion engine is connected to wheels via eCVT and pumps air through engine.

[@MatteoBurroni]

Thanks for the info, so it works like all the other Toyota hybrid. Anyway in B mode the petrol engine runs continuously in order to slow down the car, it's like as you said at the beginning putting a low gear in order to save the brakes. Since on the Toyota hybrid when the battery is full the regenerative brake drops (otherwise you'll overheat the battery), the only way to avoid the brakes is to kick in the petrol engine and let it "absorb" the energy. Unfortunately to do this the ecvt has to burn some petrol, instead of the "standard" car that doesn't burn at all when the engine is drag. Maybe in USA is not so useful, but try to come in Italian appennini's roads whitout using the B and you'll burn your brakes after the first hill :)

[@allenfischer6472]

I like to B mode for going around sharp corners on Highway ,it help you keep in Control

[@allenfischer6472]

I love theToyota Prius 2016 sport suspension too

[@dcabana1]

I've had my 2012 Prius now for a month and I've been using the B whenever I want to slow &stopfrom around 70 mph. Will this cause the engine to over reve,and possibly damage the engine?

[@10babiscar]

it should have a fuel cut off for when the engine is being driven by the cars inertia, this is what happens in all modern cars.

[@Maximonious]

Technically... the engine is not "running"... it's just spinning faster... to duplicate downshifting... and not sucking down gas!

[@rickkern5785]

The poor mileage he is getting indicates it is burning gas...

[@cybergypsy6380]

I really need more Info. like this, well done... Thanks

[@anthonymalovrh2912]

I have maxed out the bars on my 2010 Prius using B mode in the Smokey Mountains.

[@ArkDiabLord]

I hardly steps on the break, I've always use the Break mode, to exit a highway or slow down from the traffic or slide down from a hill, 50,000+ odo now and the breakers condition are still excellent!

[@130rapid]

The best for long transmission durability is changing from Eco to B when speed is constant. To prevent a jerk which happens because mode change when slowing down.

[@nickhahn5412]

唐托尼 brake*

[@WujoJulo]

Great explanation. Thanks from Poland 😊

[@jettlash1000]

You are welcome!

[@demagab]

I think the engine stays on in B mode so it can additionally slow down the vehicle in the same way when you downshift a gas vehicle down the hill

[@robertrose3068]

Awesome explanation! I have a 2014 Prius V 5 on the way from LA (Carmax) so I'm learning all I can about these. I'm a techie person so I already know this will be fun to drive.

[@haroldingpatrick1924]

Try using the cruise control to hold the speed going downhill - my 3rd generation model will automatically employ heavy regen (filling the battery completely full, the only time I see it) and then engine braking to hold the speed. It's kinda like the hill assist mode on Ford hybrids. I'm curious if the 4th gen does the same thing - let us know! Thanks for the videos.

[@allenfischer6472]

Yes, the cruise does Hold the Hills with the 2016 Prius

[@ralanham76]

In 2013 Prius you can't set cruise in B mode

[@Paulviet]

I do the same with my Prius C, cruise control set and press it down a few times to slow the car down even.

[@gushammerly5345]

I think B mode works better for very steep downhills, never felt the need to use it. In long hill descends I just use cruise and it regens until the battery is full, then the electronics make the engine brake. Very smooth transition from elecric regeneration to cvt controlled engine braking. Best cruise control of any car I ever driven. B mode may be better suited for long descends on sinuous curvy roads where it would be inconvenient to drive with cruise control or normal mode could overheat the brakes.

[@regalswim]

I just subscribed. Good luck getting from 9.99K followers to 10,000. I was hoping I would be the one to push you over the edge.

[@adam_explosion]

Can you shift to B while the car is still going or do you have to fully stop?

[@tekinbozbey6551]

B mode is also very useful in low speed very busy traffic, keeps not to touch to break very often.

[@vink6163]

Problem is, then you're burning fuel to use the engine to slow down. If you use the brakes then the car puts that energy into charging the batteries instead, so you can get that energy back later to accelerate again, saving fuel. The car doesn't use the brake pads unless you stamp on the brakes, which is why they last for so much longer than on other cars. The only time you need to use B mode is when you need to do a lot of braking and the batteries are full, so there's nowhere for the excess energy to go. B mode burns fuel to shed that excess energy.

[@MBarram]

Prius isn't using a CVT transmission as used in other vehicles. The Electric Motors (2 of them in non-awd versions) are used as generators when not in use. B-Mode forces the Electric Motor into Generator mode increasing induction to the drive-shaft and slows down the wheels/car. The generated energy gets stored in the battery pack. The fact that this car is not using a conventional transmission or CVT and the inline configuration of all 3 motors - petrol engine and 2 E-motors make it possible to use this car even when the battery will go bad. The Prius drive system uses e motors to keep the petrol engine in a sweet-spot for rpm and drive-shaft load using advanced electronics resulting in good fuel economy. Watch as reference "Niels Blaauw - Prius Hybrid Drive Explained". One reason why the Prius is mechanically a reliable car: simpler "transmission", no conventional starter motor, engine running at ideal load and rpm. Keep fluids right and you will enjoy a great car for a very long time (ps don't forget to change the air intake filter for the batteries)

[@Escorpio123PS]

Just found your channel. Just saw you explained Prius stuff. Subscribing. :). Keep it coming :).

[@johnpi1342]

B mode is just like a truck's engine brake. It'll slow you down when engaged.

[@0608kmillard]

Not like a truck's engine. Are you referrimg to "jake brakimg" (compression)?

[@307Smallmouth]

I just bought a 2017 Prius and this was great information! I was wondering what B mode was.

[@Hilljoona]

The B mode doesn't affect the charge, like many people seem to think. In fact, the engine is charging better in D mode, because the combustion engine does not brake the car by using part of the driving force. Moreover, this is perfectly visible in this video. In D the load bar fills up completely, while in B it only goes up to a third. Moral: in B, you brake more and better, but you don't charge the electrics better or faster. I don't even know if we're really saving fuel anyway. But I do know that it avoids the need for brake discs. So good point for the mechanics.

[@officebear4637]

I love Prius videos, even though I don't own one they're relaxing. Prius drivers are so easygoing. Refreshing from all those crazed soccer moms I see on the road who give me road rage when I don't go 0-60 in 5 seconds.

[@jettlash1000]

Hahahaha.

[@steveturpin4242]

Well done and thanks. Now I know how to drive my new Prius beauty. cheers

[@alexs6545]

When going down the hill- does it have to be one or the other? use only Cruise Control or use only the B mode?

[@nationofgandhis]

I think the cruise control is unavailable? priuschat.com/threads/ev-b-rake-mode.179453 2020 manual p. 406 ■Situations unsuitable for dynamic radar cruise control with full-speed range. ●On steep downhills, or where there are sudden changes between sharp up and down gradients Vehicle speed may exceed the set speed when driving down a steep hill. p. 415 : ■Dynamic radar cruise control with full-speed range can be set when ●The shift position is in D."

[@Mike-sk4dj]

This should've been a two minute video. I really didn't need five minutes of you blathering on while you drive up a hill waiting to find out what "b" mode is.

[@konstantinusstoyanov9749]

I did not have any ideas, great video

[@jettlash1000]

Thank you!

[@MontyGumby]

you do that all the times ? - looking to the rear when backing up (instead of just relying on the camera)

[@Clayton139]

This was great explanation and demonstration of B-mode on the Toyota Prius. I am in hopes that you will do more video explanations and demonstrations on the Toyota Prius... Especially the Gen-4 Prius for me :) Very informative!

[@Boss-gk1ym]

Awesome this vid helped a lot! Thanks man!

[@jimscheltema670]

Does B-Mode provide battery charging similar to the regenerative braking?

[@Hilljoona]

Yo, it doesn't affect the electric recharge. Basically you don't charge better with the B mode, in fact it's quite the opposite.

[@cyndie26]

In some places, truckers aren't allowed to use their engine brakes/Jacobs brakes/Jake brakes at night. Does that apply to this Prius feature?

[@MrMariohere]

Probably not because the reason the trucks are not allowed to is based on the loud noise that it makes. I'm pretty sure the Prius is quiet.

[@cyndie26]

Is it also because of the way each feature works? (e.g. On a truck's engine brake, air gets released from the cylinders, thus lowering the amount of air the fuel can react with. For some reason, I don't see that happening with a Prius, but possibly with a big diesel engine.)

[@TheShamarski]

enator71 I know I'm late, but just in case you haven't found out. engine braking works by slowing the car with the compression of the engine. No fuel is used. The higher the RPMs, the more the wheels have to turn over the engine. Precisely why engine braking in 1st is stronger than 5th/6th in a manual. I can only explain for most manual cars, I can't comment on other vehicles really

[@wjj4832]

Where you were coming back down in B mode and the car slowed below 25 MPH, I would have dropped over to Neutral for a few seconds to pick up speed, as opposed to stepping on the gas. When the speed picked up adequately, I would quickly bump it into Drive and back into B mode. This has been very effective for me, and I now have 137K miles on my 2011 Prius with no battery or engine problems. Best tank to date was over 600 miles, averaging 65.2 MPG (all in-town driving in a single day.

[@jettlash1000]

Nice one!

[@bushputz]

Alternately, you can go between Drive and B mode. That's what I do when I'm coming down I-70 from a day of skiing. I can usually control my speed to match traffic this way, rarely touching either the gas or brake pedals all the while charging the battery.

[@niubaiwan]

Will using B mode accelerate the charging speed of the battery?

[@waterflawsnomdeguerre2045]

Coming down a very steep and long mountain road (in Colorado) our Prius started making strange noises in B-mode. Any ideas/observations?

[@jettlash1000]

Is it only when the battery gets fully charged, or is it anytime the prius is in B mode?

[@waterflawsnomdeguerre2045]

It seemed to be AFTER the battery was charged, and the noise continued, whenever I put it in B mode, until I got to the bottom of the hill and shifted to D. I've been afraid to turn it on again.

[@jettlash1000]

I would say my car also sounds slightly different in B mode and after the battery is fully charged. If it isn't a bad sound, it could just be due to the hybrid system changing it's cycle.

[@Espr14]

If the noise is like full power engine running up the hill then it is OK.

[@RennieAsh]

What kind of noise? The petrol engine will "rev up" to do the engine braking that would normally happen in other cars. It's not using fuel during engine braking of course, only uses the car's momentum to spin the engine.

[@camfam52002]

B mode in a Prius simply spins the ICE without firing it to simulate engine braking. In effect it diverts energy through the engine rather than the generator as it won't provide the level of retardation required for steep descents. The reason you see that the engine is on is because the crank angle sensor reads as if it running, when ofcourse it's not. Don't use it, it is dumping the kinetic energy that you can otherwise divert to the battery pack. Lightly touch the foot brakes to increase the field strength of MG1 and maximise the efficincy.

[@stargazer7644]

This is incorrect. There is no direct connection between the wheels and the engine in a prius. Both D with light brakes, and B mode regen and charge the battery. Eventually however, the motor will start and it will reduce regen. I suspect something begins to overheat. Regen charges the battery very quickly.

[@SHx589]

How does the Prius handle steep heels 👠

[@rainafortini5797]

Unclear. So it ships out of B-mode automatically when exactly? Is it possible to forget to take it out of the mode because I don’t see you using your hand actually shift anything it just automatically went out of the mode because you accelerated or stepped on the break?

[@asadullahwafa8897]

Can I drive my Prius on B mode in the highway?

[@LivnLife92]

I've noticed as well when driving my 2016 that if you have cruise control set & start going down hill it seems to automatically kick in Engine braking although the indicator doesn't show it in "B" mode trying not to go past the set speed & man i can imagine how quickly you would have gained speed going down the hill in neutral because mine definitely gains speed even quicker in neutral going down hill =p

[@ArnoldJagt]

While the engine may be turning in "B" mode, it is not getting any gas or spark, just air. By the way, "B" mode is great for stop-and-go traffic as it slows you down nicely whenever you take your foot off the gas pedal.

[@AmericanRoads]

Instead of B-mode, what would happen if you stay in D-mode and partially depress the brake pedal (enough for regen, but not enough to engage the physical brake) as you are travelling down the hill? In other words, you are regen-braking all the way down. Is regenerative braking alone enough to keep the downhill speed under control?

[@jettlash1000]

On this hill, the brake itself would use the physical brakes to keep speeds in check. In B mode, it didn't require any use of the physical brakes.

[@jasonmartinez7667]

Is B mode like regenerative braking on Tesla?

[@heidiborton5284]

I have noticed in B mode, with the battery fully charged, the engine makes much more noise when running. I am not sure if that is because the battery is fully charged? It is a little worrisome. Do you notice this too? Is it a problem?

[@jettlash1000]

I didn't notice the engine being louder, but I do notice more power when the battery is full.

[@MontyGumby]

so you're implying that B-mode, going downhill, charges the battery more effectively ?

[@richt8113]

Suppose you're going down a hill beginning at 55mph and you want to control your speed. Can "B" mode be used at this higher speed?

[@timogronroos4642]

You can use it in whatever speed you want, even with adaptive cruise. It's just to simulate engine brake like in traditional transmissions to save your brake pads. Remember Toyota Hybrid Drive does not have any gears, so it can't change into lower gear, it uses software programmer magic when B is activated

[@anitaphillip8772]

@@timogronroos4642 so can I say B is like shifting to a lower gear, like in a Manual to Gear 1?

[@dmccarthy100]

I also have a Prius (2016). when in B mode and it's strictly charging the drive battery, if you change your MID to display the electrical layout it shows that the wheels are charging the battery but the ICE is not engaged/active. So it is in a sense in EV mode, but not showing the green ev icon

[@jettlash1000]

Good feedback, I'll have to look at that!

[@hamodah82]

Can I shift from B to D mode at the end of the hill while driving?

[@jesseobrien5864]

First. Thank God for you. I watched so many videos that just wasted my time until you showed up. Second. So you just shift on the fly right? Does it stay in B until you pop it back up? Do you have to shift back to drive from B? That's cool. So basically find a hill. Charge it and your Gucci. I'm gonna read the manual. But this helped a lot for a 2013 Prius Persona

[@EddiePassions]

do B itch mode grabs strongly?

[@ronaewilson5843]

I used B mode for the first time going down a hill however the rpm started to climb rapidly.is this normal?

[@PITU-f7f]

Do you need to press break before shifting from D to B?

[@robertolouth7468]

Very interesting seeing the way this Prius works. Probably going for my first Hybrid soon. Do you think I will miss my Camry’s comfort and 2.5 + 8 speed transmission kick?

[@jettlash1000]

The Prius is pretty comfortable. I've ridden in a Camry and they felt pretty comparable.

[@symmetry08]

I think, those engineers have put an additional B1,B2 and B3 modes so that to vary power of recycling and how fast it will descend.

[@qztronic]

symmetry08 there's no B1 B2 unfortunately, but we balance the energy input and output in B mode, that's why the engine kick-in to create heat loss as load (free pumping with no fuel injected) , it also rev higher according to the excess regeneration resulting is a dynamic effect (the car mimic engine-brake harder the more you press the brake pedal)

[@cutflow2]

Can you use b mode to slow down on the highway when the traffic up ahead is slowing down or still

[@VocalVirgo]

You said you've never had 8 bars/a full battery… But at 7:36 seconds, your battery shows it just reached 8 bars/full battery. You can thank B mode for using what would normally be wasted energy and wasted brake pads to charge your battery as well. :-). The B mode is your friend, especially in a Prius Prime.

[@jettlash1000]

Very true, you normally wont hit 8 bars under normal conditions.

[@alext9067]

Do you feel that the engine is slowing you down or is it the regen braking?

[@bobbabai]

alex tworkowski I'm guessing regen is used less in B mode and the gas engine is more directly coupled to the wheels by the drive system, allowing greater use of normal gas-engine high-vacuum braking (the gas engine revs higher in B mode).

[@BillGrates1]

it would be good if you could tell us how much money in gas it saves using B mode instead of D on hills. thanks.

[@cadacabezaesunmundo6496]

I have never had a Prius, but My next car may be a hybrid so I am learning. Could B mode be intended for short hills then?

[@CoronaBier-pn6gm]

Yes, and when the battery is full and therefore no regenerating is engaged anymore. Regenerative braking power is about at least 20 kW (differs because of the variance in HSD models) when you touch the brake pedal and in B-Mode engine braking comes on top which are about 35 kW. Engine braking power in Toyota hybrids is not as high as in conventional gear-driven cars at low gears with high engine rpms because the HSD although it is continous variable in gear ratios with the help of the Engine-Generator 1 it is more limited. Therefore engine rpm is lower than in conventional gear-driven cars and so is engine braking power. But you get the regenerating power on top and you are even or better. Only on long hills and especially the non plugin Toyota version with the small batteries which are charged full in a small time and from then on no regenerating power. Therefore it makes sense to put the car in B-Mode on steep hills or long desecendings to give the mechanical brakes a longer time to dissiapate the heat.

[@dessieb123]

Do you have to put your foot on the brake, to engage B mode? Great video

[@jettlash1000]

No you don't, thank you!

[@Realistis]

I don't have this kind of slope nearby. On my European Prius, I can force EV (below 50km/h). I wonder what happens in B mode in EV only: 1- charge faster (gears ratio on electric motor only), 2- starts ICE to use gears ratio on ICE, 3- it does 1 then 2 depending on battery levels to prevent overcharging. Or maybe I don't need to force EV at all.

[@amandastansfield4896]

Excellent explanation .

[@Obelisk57]

How's this any different than down shift into L in any traditional automatics? I do that all the time in my old car?

[@nickhahn5412]

I love the videos man thanks a lot

[@jettlash1000]

You're welcome!