Warm-up Period

[MEP's Yaris GS]

Well

I think I found my idea driving style....

1. No warm up required

2. Start as usual

3. ECO button ON

4. Leave stereo / aircon on if want to

5. Drive as civilised as possible, if need more grunt then right at top of ECO bands

6. If want more GRUNT or uphill, then do not think twice about pressing PWR button - and use leisurely :)

7. Use B position on gearstick for longer than usual (or steep) downhill

Initial AVERAGE MPG has shown I got the BEST figures yet! :) :) :)

And I HAPPY with the driving style too (ECO to save fuel, PWR go have fun!)

I agree with everything except 7, B should be used as infrequently as possibly as will be wasting energy rather than maximising regen from it.

IMO should only use it on steep hills where brakes are not enough and when the Battery is maxed out, although the car will automatically do the equiv of B mode anyway at that point.

[Wayne2015]

Well

I think I found my idea driving style....

1. No warm up required

2. Start as usual

3. ECO button ON

4. Leave stereo / aircon on if want to

5. Drive as civilised as possible, if need more grunt then right at top of ECO bands

6. If want more GRUNT or uphill, then do not think twice about pressing PWR button - and use leisurely :)

7. Use B position on gearstick for longer than usual (or steep) downhill

Initial AVERAGE MPG has shown I got the BEST figures yet! :) :) :)

And I HAPPY with the driving style too (ECO to save fuel, PWR go have fun!)

I agree with everything except 7, B should be used as infrequently as possibly as will be wasting energy rather than maximising regen from it.

IMO should only use it on steep hills where brakes are not enough and when the Battery is maxed out, although the car will automatically do the equiv of B mode anyway at that point.

Is it?

I thought B apart from like-engine-braking it also increases the Battery charge up?

Why does it wastes energy?

[MEP's Yaris GS]

Well

I think I found my idea driving style....

1. No warm up required

2. Start as usual

3. ECO button ON

4. Leave stereo / aircon on if want to

5. Drive as civilised as possible, if need more grunt then right at top of ECO bands

6. If want more GRUNT or uphill, then do not think twice about pressing PWR button - and use leisurely :)

7. Use B position on gearstick for longer than usual (or steep) downhill

Initial AVERAGE MPG has shown I got the BEST figures yet! :) :) :)

And I HAPPY with the driving style too (ECO to save fuel, PWR go have fun!)

I agree with everything except 7, B should be used as infrequently as possibly as will be wasting energy rather than maximising regen from it.

IMO should only use it on steep hills where brakes are not enough and when the Battery is maxed out, although the car will automatically do the equiv of B mode anyway at that point.

Is it?

I thought B apart from like-engine-braking it also increases the Battery charge up?

Why does it wastes energy?

It doesn't increase regen braking (I believe someone on Prius chat tested it with an amp meter in the states) it just engages the engine for engine braking, and as such wastes energy through heat from the engine block, rather than converting it into electricity to top the Battery up.

[Wayne2015]

Well

I think I found my idea driving style....

1. No warm up required

2. Start as usual

3. ECO button ON

4. Leave stereo / aircon on if want to

5. Drive as civilised as possible, if need more grunt then right at top of ECO bands

6. If want more GRUNT or uphill, then do not think twice about pressing PWR button - and use leisurely :)

7. Use B position on gearstick for longer than usual (or steep) downhill

Initial AVERAGE MPG has shown I got the BEST figures yet! :) :) :)

And I HAPPY with the driving style too (ECO to save fuel, PWR go have fun!)

I agree with everything except 7, B should be used as infrequently as possibly as will be wasting energy rather than maximising regen from it.

IMO should only use it on steep hills where brakes are not enough and when the Battery is maxed out, although the car will automatically do the equiv of B mode anyway at that point.

Is it?

I thought B apart from like-engine-braking it also increases the Battery charge up?

Why does it wastes energy?

It doesn't increase regen braking (I believe someone on Prius chat tested it with an amp meter in the states) it just engages the engine for engine braking, and as such wastes energy through heat from the engine block, rather than converting it into electricity to top the Battery up.

In that case....it will be back to the "engine braking vs wearing disc/pad down"

I would still prefer to use B then :)

Let me dig out user manual....were sure it said increases battery charge...or did I read it on the Toyota website....

[MEP's Yaris GS]

Main dealers have been known to incorrect advise on it. So that maybe where you've heard it.

Like you say if you've maxed out regen braking in D and need more then use B, but if you can get away with using regen braking and going near to, but not over, Max then you'll be better off doing this, as the friction brakes don't kick in until it's been maxed out so you won't be cooking them :)

[YarisHybrid2016]

The B mode does increase regen braking ONLY for the case where your feet are clear of both pedals, otherwise it is the equivalent of slightly applying the brake to increase regen braking in D mode (IIRC it drops to the first tick mark in the blue).

[Wayne2015]

Interesting article here:

http://prius.ecrostech.com/QandA/BMode.htm

>>>

Questions about B Mode

When to use B Mode

Use the B position of the Mode Selector Lever in exactly the same circumstances as you would change to a lower gear to slow down a conventional car. If you are going down a long and steep hill, controlling the car's speed using only the brakes can cause them excessive wear, get them hot and may also tire your foot. The solution in a conventional car is to select a lower gear. The engine then spins faster and the energy it takes to do this holds back the car. Less brake pressure is needed to maintain a slow rate of descent. The Prius, however, has no gearbox in the usual sense of the term. Toyota have made special provision for engine braking and to activate this you put the Mode Selector Lever in the B position. By a special configuration of the motor/generators, the engine spins and helps hold back the car just as in a car with a gearbox (see How B Mode works, below).

When not to use B Mode

There is no benefit to using B mode in a situation normally calling for the use of the brakes (except one, see Advanced uses of B Mode below). If anyone, even someone who should know what they're talking about, tells you that in B mode you recover more charge to the Battery, they are wrong. You recover less for the simple reason that the purpose of B mode is to throw energy away by spinning the engine. The B does not stand for Battery, it stands for Brake. However, as far as I know you will not hurt the car by using B mode inappropriately. If you press the accelerator, there is no difference between B and D modes. So, if you don't care about recovering braking energy to the Battery and you get a kick out of flipping the Mode Selector Level to slow down, by all means do so. Just don't be surprised if other Prius drivers roll their eyes at you.

Advances uses of B Mode

There are two situations in which B mode has been found useful other than descending long steep hills.

The first is in slow descents of bumpy roads when you might not normally think of using engine braking. What happens in such a descent is that the car's traction control system disengages the regenerative braking system. This means that you are not recovering very much of the energy of the descent as charge in the battery. You won't hurt the car and there is no need to do anything about this except to brake a little harder, which you will do automatically. But, if you want to recover as much energy as possible, you can switch to B mode. A side-effect of the way in which B mode works causes an increase in battery charging at lower speeds when regenerative braking is disengaged. Note that if regenerative braking were to operate, for example if you reached a smooth section of road, you would get the most regenerated charge by switching back to D mode and increasing brake pressure. It may be necessary to release the brake for an instant to let regenerative braking reset itself.

The second is in stop-and-go traffic queues. Normally, when you move the car forward you will use battery only mode and the engine will not start. After a while, however, the battery charge level drops and you will find the engine starting for each short movement and then shutting down. There is nothing wrong with this, but if you find it annoying you can switch to B mode during a forward lurch. When you come to a stop, the engine will continue to run and charge the battery for a while. Why this happens is not understood.

>>>

[Wayne2015]

This confuses me

No it does not charge Battery

Yes it does!

No it dosent!

https://en.m.wikibooks.org/wiki/Toyota_Prius/Driving_tricks

[YarisHybrid2016]

A side-effect of the way in which B mode works causes an increase in battery charging at lower speeds when regenerative braking is disengaged.

Confused...I thought regen braking (AKA "decelerate the car by applying electrical load in the form of recharging the HV battery") was disabled in certain situations, meaning ALL energy is lost somewhere else (mechanical brakes and/or engine braking). If regen braking is disabled, then B or D mode doesn't matter - it's disabled???????

The second is in stop-and-go traffic queues. Normally, when you move the car forward you will use battery only mode and the engine will not start. After a while, however, the battery charge level drops and you will find the engine starting for each short movement and then shutting down. There is nothing wrong with this, but if you find it annoying you can switch to B mode during a forward lurch. When you come to a stop, the engine will continue to run and charge the battery for a while. Why this happens is not understood.

Does the engine ever stop in B mode? Might be related to preparing the engine to switch to braking mode?

To pour more fuel on the fire...I have seen it written that use of B mode can increase fuel usage in normal driving. If the engine will keep running, and won't for example enter EV mode, then that would make sense.

What I have never seen adequately clarified is this:

Is it OK to drive, AT SPEED AND FOR EXTENDED DISTANCES in B mode, not counting the fact the car may not enter EV mode?

As I understand it, B mode configures the engine timings so it is as inefficient as possible to maximize energy losses during deceleration (no fuel injection or combustion takes place). Does this translate when accelerating in B mode, or does the computer switch to D mode configuration when power is demanded (no matter how slight)? The few times I actually used B mode on a hill, the transition from engine braking to power delivery was seamless, and no change from D mode was observed.

I'll go take it out for a drive and see if I can hear any difference between D and B modes under power.

* goes to lie down in a darkened room *

[PeteB]

When in B mode, pressing the accelerator enough to maintain or increase speed will disable B mode, but as soon as the accelerator is eased off enough to cause loss of speed B mode kicks back in.

Unless the HV Battery is maxed out, you will get some regeneration while in B mode, just not us much as without.

Regen braking will not occur if you put the car into N while moving and hit the brakes. Some people do this occasionally to de-rust the discs.

Another use for B mode is on icy/muddy/snowy roads, when it sometimes allows better control with easing back on the accelerator than just braking.

[johalareewi]

the purpose of B mode is to throw energy away by spinning the [petrol] engine

[Wayne2015]

When does the AVERAGE or/and INSTANT MPG get stuck on 99.99mpg?

I know they show that sometimes when u coasting or downhilling fast etc

But its never happened on my Auris yet

And certainly not get STUCK on 99.99mpg for a good few miles - eeek!

Try pressing the button a few times - but no good.

After a few more miles it went back to normal....

[YarisHybrid2016]

I usually see 99.9 any time it's in EV mode, or the power needle is at one tick mark above the middle of ECO or lower with the car at a steady speed. It would appear that even if the ICE is running in this condition, there is sufficient torque from the electric motor that it can completely idle the engine.

Interestingly, in EV MODE, you can accelerate to the tick mark above the middle of ECO without the ICE starting, but not in normal mode (in NORMAL, going above the middle of ECO will start the ICE). I'm thinking there is something to this when the ICE is running (it's acting only as an electrical generator).

[Wayne2015]

Cheers :)

The only reason I asked is because it would skew my average mpg....

[YarisHybrid2016]

It's a good skew, surely?! :D It increases the MPG towards what it really is. If the ICE is running and pulling the car then instantaneous MPG drops significantly.

[Wayne2015]

It's a good skew, surely?! :D It increases the MPG towards what it really is. If the ICE is running and pulling the car then instantaneous MPG drops significantly.

Lol

[Lesolee]

Well

I think I found my idea driving style....

...

7. Use B position on gearstick for longer than usual (or steep) downhill

Using B mode is never good for fuel consumption! You are just wasting regeneration power. The only use for B mode is when you have fully charged your Battery going downhill and you need to slow down. Rather than burning out your brakes on a long descent (since you can't regenerate into your now full battery) you can use engine braking.

[johalareewi]

...

The only use for B mode is when you have fully charged your battery going downhill and you need to slow down. Rather than burning out your brakes on a long descent (since you can't regenerate into your now full battery) you can use engine braking.

FWIW the Gen3 Prius (and I imagine later Toyota Hybrids) automatically use B mode when the HV Battery is full.

B mode is also useful when driving in snow.