Electronic Brake on IS ?

kal · October 2, 2017

I'm considering looking at the IS for my next car. I currently drive a CT which has a "B" on the gear slots for regenerative braking. Ideal when rolling down slopes.

Is there anything similar on the IS?

PaulWhitt20 · October 2, 2017

No

But you can use the flappy paddles to select a lower "gear"

bluenose1940 · October 3, 2017

I use my paddles all of the time to keep within the speed limits when going downhill.

NemesisUK · October 3, 2017

Not on an IS but I always use the foot brake on my RC300h, doesn't use the discs and pads and gives much better regen results. Using the paddles brings in the ICE to provide the braking force

kal · October 3, 2017

20 minutes ago, NemesisUK said:

Not on an IS but I always use the foot brake on my RC300h, doesn't use the discs and pads and gives much better regen results. Using the paddles brings in the ICE to provide the braking force

Sorry not sure what you mean?

"I always use the foot brake on my RC300h, doesn't use the discs and pads"

NemesisUK · October 3, 2017

1 hour ago, kal said:

Sorry not sure what you mean?

"I always use the foot brake on my RC300h, doesn't use the discs and pads"

For gentle to moderate braking the hybrid will use MG1 as a generator to retard forward motion. The mechanical brakes, i.e. discs and pads will come into use with more severe braking and once down to much lower speeds (I think it's approx 5-10mph?)

Using gentle braking whilst descending a hill in a hybrid will recharge the batteries. In a normal car one would usually use the gears to invoke engine braking to help prevent brake fade.

Ala Larj · October 3, 2017

I occasionally use the flappy paddles on my GS to slow down but have noticed that recharging is less than when using the brakes. However, the flappy paddles feel more 'realistic' and similar to driving a manual.

Carl1983 · October 3, 2017

I know what you’re on about with the B mode my Toyota had that. In the IS you can use the steptronic or paddles to move through the gears, when you shift into the lower gears you can feel it holding you back and going into charge

rayaans · October 4, 2017

Agree with all the above comments.

Stick your foot on the brakes rather than using the paddles - much more regen that way and doesn't use the mechanical brakes.

Bratman91 · October 6, 2017

On 03/10/2017 at 9:13 PM, NemesisUK said:

. In a normal car one would usually use the gears to invoke engine braking to help prevent brake fade.

In days well past when drum brakes were the norm, it might have made sense to employ engine braking to avoid brake fade. However, I really do doubt that modern disc brakes with better air flow for cooling ever suffer from fade under any but the most extreme circumstances. Why use highly expensive gear boxes and transmissions to do what relatively inexpensive brakes are designed to do? I have hardly ever used engine braking since the days when I was a boy racer and it seemed macho to show my "skill" at driving.

Ala Larj · October 6, 2017

Not sure I'd just really on the brakes when driving down a mountain road!

Bratman91 · October 6, 2017

15 minutes ago, Ala Larj said:

Not sure I'd just really on the brakes when driving down a mountain road!

I did say "any but the most extreme circumstances" but, even so, if you think that the brakes are fading, you can always change down.

Britprius · October 6, 2017

On 10/2/2017 at 7:08 PM, PaulWhitt20 said:

No

But you can use the flappy paddles to select a lower "gear"

The basis of the Toyota/Lexus hybryd transmission apart from the very latest versions is that they do not have any gears to change. Not even for reverse. Everything is a balancing act of the speed, direction, and if MG1 is being used as an electric motor or a generator. MG2 is coupled to the wheels at all times, and when they are turning so is MG2. This also can be used as a motor or a generator. This also gives reverse by MG2 being driven backwards. If the engine runs while going backwards it impedes the action of MG2 as the engine is running in the wrong direction for reverse.

The friction brakes are arranged to work if the ABS system senses a wheel slip, the high voltage Battery becomes full charged "actually only 80% full" or the current generated under heavy braking is to high for the safety of the HV Battery. They also work below 7 mph as there is to little kinetic energy going to the generators to stop the car.

John.

bluenose1940 · October 6, 2017

I will happily continue to use my paddles. It's much easier sometimes to 'change down' to third gear to maintain the car within the speed limit, especially in a 30mph and even more so in a 20mph zone.

rayaans · October 6, 2017

2 hours ago, Ala Larj said:

Not sure I'd just really on the brakes when driving down a mountain road!

It won't be using the mechanical brakes for most of the braking though - only at lower speeds.

Ive managed to get down roads using just the brakes on my RX - all 2.1 tonnes of it and it was charging all the way down rather than using the mechanical brakes

kal · October 6, 2017

Wow, I've had my CT now for 4 years, but I've now learned something about how it runs that I never knew about. Never knew about the MG1 and MG2. Thanks for the info.

Found this quite informative...

http://prius.wikia.com/wiki/Hybrid_Synergy_Drive_(HSD)

NemesisUK · October 6, 2017

1 hour ago, rayaans said:

It won't be using the mechanical brakes for most of the braking though - only at lower speeds.

Ive managed to get down roads using just the brakes on my RX - all 2.1 tonnes of it and it was charging all the way down rather than using the mechanical brakes

I do this every time I go home, long steep downhill recharges the traction Battery ready for a silent departure next day