regen braking

[cruiserOAP]

The Yaris Cross manual isn't clear on exactly when braking switches from regen braking to friction braking when slowing down. I'm assuming that light braking is using the generator rather than the brakes, but there's no indication on the dashboard when the brakes kick in during harder braking.

Also, there seems to be some confusion by road testers about B mode. The manual describes B mode as engine braking, whereas some road testers call it extra strong regen braking.

The speed limiter and the cruise control both brake the car going downhill to keep to the set speed. I assume it's using regen and not the brakes to do this? I would like to use regen braking instead of the brakes as much as possible, but it's not obvious which is which when slowing down.

[anchorman]

It varies Mike depending on Battery charge but it blends the two automatically.   The regen mode does the same and then when the Battery is fully charged, it takes the field off the motors to let them freewheel.  At that point it handsoff to the engine for overrun braking and you’ll hear the engine revving.   Trouble is the Atkinson cycle doesn’t lend itself to engine braking so despite it connecting directly to the epicyclic box, it can’t generate much retardation.   You can force more regeneration by using the B mode up until the Battery getting fully charged.  Some of the rubbish the journalists come out with - they’ve clearly just flicked through the press pack.  I read one on a UX the other day saying the paddle shifters give it 12 speeds.   There are just a way of stepping regen or power modes.  

[Ralph H]

Something I’ve noticed in my mk4 is when slowing down gradually I can definitely feel when the braking changes from regen to actual brakes. I get a slight release of the brakes when it changes over requiring slightly more pressure on the pedal.
I never noticed this on my mk3 but it’s brakes were more grabby. 

[jthspace]

When I had a Mitsubishi PHEV, I used regen braking which was more effective than the Yaris.  However, I was told more than once my brake lights were not working so always good to touch the brake pedal to let the car behind know what's happening. 

[MikeSh]

This is how I see it on my MK3, but I expect it's going to be the same.

The limit for the main motor supplying power or braking (generating) will likely be the same kW/Amps. On the power display the mark beside the letters ECO is the same distance up from the 0 as the bottom of the regen scale is below. On mine the engine will always run if the power is above that mark beside the eco tag, so I deduce that that is the maximum the motor can produce and therefore the bottom of the scale is the maximum it can generate (braking). I assume that when the needle goes below that then friction brakes will be added.

So I just try and keep the needle inside the regen scale to maximise regen and minimise friction brakes.

[TonyHSD]

2 hours ago, Ralph H said:

Something I’ve noticed in my mk4 is when slowing down gradually I can definitely feel when the braking changes from regen to actual brakes. I get a slight release of the brakes when it changes over requiring slightly more pressure on the pedal.
I never noticed this on my mk3 but it’s brakes were more grabby. 

This happens because of two reasons: 1 the actual brakes are either new and not bedded in yet or 2 there are  rust accumulated on the friction surfaces and or stuck slider pins.
Perhaps you can do a couple of moderate to progressive when coming off A road or motorway to help polish the surfaces and reduce any noticeable difference aka switch between regen and actual brakes.
In rare cases can be the other way around and some describe it as grabby brakes., this often happens when driving in heavy rain and your brakes gets wet, first they will be weak, weaker than a car without regen braking because they will dry the discs slower, something all hybrid owners has to have in mind , then they will become grabby and then after some more drive they will clean themselves and work normally again. 
The B mode in Toyota hybrids uses regeneration more indeed and the cruise control uses regen to slow down the car, this can be seen on power meter. There are also two different  types of reviving up the engine, the first one as explained is to maintain speed and the second one is to discharge the Battery, this is when the rpm goes very high for a short time and also the engine may start after you had completed the descend or have come to a complete stop at junction, traffic lights etc. 

[Ralph H]

Once left my mk3 hybrid stood for a week and the rear brake stuck on, so now I like to give the brakes a good workout every now and then when exiting the motorway probably at least once a week. Seems to keep them rust free it also helps that the car is used most days. I only noticed the transition between regen and real braking when I first got the car although it still does it now i don’t notice anymore.

[cruiserOAP]

17 hours ago, cruiserOAP said:

The Yaris Cross manual isn't clear on exactly when braking switches from regen braking to friction braking when slowing down. I'm assuming that light braking is using the generator rather than the brakes, but there's no indication on the dashboard when the brakes kick in during harder braking.

Also, there seems to be some confusion by road testers about B mode. The manual describes B mode as engine braking, whereas some road testers call it extra strong regen braking.

The speed limiter and the cruise control both brake the car going downhill to keep to the set speed. I assume it's using regen and not the brakes to do this? I would like to use regen braking instead of the brakes as much as possible, but it's not obvious which is which when slowing down.

I'd like to see an indication on the dash when the friction brakes kick in - perhaps an orange light? This would help to maximise regen braking and reduce brake wear.

I'd also like a rev counter on the dash somewhere, even an led light bar would do the job, then when the engine is  running I could keep the revs as low as possible by feathering the throttle. This would be a bit like the vacuum gauge I fitted to my old Volvo. Keeping the reading as high as possible by feathering the throttle helped with fuel economy. Many hybrid owners probably aren't interested in the goings on with the hybrid system, but I like to see what's going on in there.

To nerdy types like myself, maximising the efficiency of the hybrid system is satisfying, not least because I am now averaging 81.5 mpg since new, including one 30 minute cross country drive at 127.5 mpg!

 

[Ralph H]

18 minutes ago, cruiserOAP said:

I'd like to see an indication on the dash when the friction brakes kick in - perhaps an orange light? This would help to maximise regen braking and reduce brake wear.

I'd also like a rev counter on the dash somewhere, even an led light bar would do the job, then when the engine is  running I could keep the revs as low as possible by feathering the throttle. This would be a bit like the vacuum gauge I fitted to my old Volvo. Keeping the reading as high as possible by feathering the throttle helped with fuel economy. Many hybrid owners probably aren't interested in the goings on with the hybrid system, but I like to see what's going on in there.

To nerdy types like myself, maximising the efficiency of the hybrid system is satisfying, not least because I am now averaging 81.5 mpg since new, including one 30 minute cross country drive at 127.5 mpg!

 

If you have an android phone and a bluetooth obd connector you can get an app for all that and more information.
I’ve not tried any myself though. 
perhaps this one 

https://carvitas.com/blog-and-news/hybrid-assistant-obd2-app

[cruiserOAP]

1 hour ago, Ralph H said:

If you have an android phone and a Bluetooth obd connector you can get an app for all that and more information.
I’ve not tried any myself though. 
perhaps this one 

https://carvitas.com/blog-and-news/hybrid-assistant-obd2-app

That's a good idea! I do have a carista OBD device which I can activate with a subscription.

[CPN]

3 hours ago, Ralph H said:

If you have an android phone and a Bluetooth obd connector you can get an app for all that and more information.
I’ve not tried any myself though. 
perhaps this one 

https://carvitas.com/blog-and-news/hybrid-assistant-obd2-app

That is definitely the best there is out there. I have been extolling its virtues for long enough here in these forums and use it daily or whenever I am driving anyway. 

It will tell you anything you need to know about your hybrid's performance. If you need any help with it, just shout... 

[YarisHybrid2016]

8 hours ago, MikeSh said:

This is how I see it on my MK3, but I expect it's going to be the same.

The limit for the main motor supplying power or braking (generating) will likely be the same kW/Amps. On the power display the mark beside the letters ECO is the same distance up from the 0 as the bottom of the regen scale is below. On mine the engine will always run if the power is above that mark beside the eco tag, so I deduce that that is the maximum the motor can produce and therefore the bottom of the scale is the maximum it can generate (braking). I assume that when the needle goes below that then friction brakes will be added.

So I just try and keep the needle inside the regen scale to maximise regen and minimise friction brakes.

I reached the same conclusion regarding my Gen.3, too!

[dannyboy413]

1 hour ago, CPN said:

That is definitely the best there is out there. I have been extolling its virtues for long enough here in these forums and use it daily or whenever I am driving anyway. 

It will tell you anything you need to know about your hybrid's performance. If you need any help with it, just shout... 

What OBDII reader would you recommend? For the money, the 'Veepeak' seems to get some good reviews.

https://www.amazon.co.uk/Veepeak-Bluetooth-Scanner-Automotive-Diagnostic/dp/B011NSX27A/ref=sr_1_8?keywords=obd2+bluetooth&qid=1693598446&sr=8-8

[isnsiie]

What I learn from the hybrid assistant is that the regen braking requires pressing the paddle very very little and holding it when you start braking, and increase the brake pressure very slightly according to the distance to the stopping point.  Thats mean you need a very long braking distance.

I can clearly see that on the hybrid assistant. MyT and car system can’t tell anything about it.

[Cyker]

On mine, there are 3 blocks for the 'regen' - block 1 is when I just lift off, 2 blocks is light braking and 3 being heavier braking.

Blocks 1 and 2 are always regen-only braking above 5-10mph - I find generally the friction brakes won't get used unless I'm braking to level 3.

That said, it's usually quite easy to tell, as I find the friction brakes very noticeable when they're cold and especially after a lot of rain.

Once they've warmed up and been used a bit, the blending between regen and friction braking is practically seamless.

I will say the regen in the Mk4 is noticeably stronger than in the previous gen HSD like the Mk3 and the Auris and seems like they do 90% of the braking in my normal driving; I feel most of the time the friction brakes only cut in during that last 5mph to actually stop the car - I think if it wasn't for the suicidal pedestrians and blind SUV drivers I routinely have to contend with, my brakes would be a lot rustier!!  

[Stopeter44]

@cruiserOAP Don’t over think the regen/physical braking switch over. 
 

Anchorman explains very clearly, IMO, what happens with regen to normal braking switch over. One becomes attuned to the different feel of the brakes as the system switches over.

 

When I first had my Yaris IV I was surprised by how the hybrid coaching section in the MyT app would tell me I was braking too late and too hard. Nowadays, that rarely happens, I’ve adjusted my driving style accordingly.

I also think that trying to outguess the hybrid system is a waste of mental energy, the hybrid system revs the motor according to what’s needed, and if you have long downhill sections, the motor will be spinning a lot, but it’s not burning fuel, nor after a certain point is there any extra energy being put into the traction Battery.

 

A number of posts on the forum on the system will point to ressources on explaining HSD, if you haven’t looked at those already.

[TonyHSD]

Absolutely agreed with last few comments.
Accelerating too gently and braking slowly won’t really add much to the efficiency., even quite opposite.
Moderate driving with progressive acceleration and slow downs with longer free rolling is the key to achieve greater efficiency and pleasant driving sensation without getting bullied by others for been way too slow. The pulse and glide technique at any speed , this actually works even on non hybrid petrol or diesel manual cars and of course all evs. When slowing down with hybrids you can use the brakes as hard as you wish and you still gonna have full regen benefits plus clean and rust free brake discs. 

[Trewithy]

I was told to keep an eye on the Charge/eco/power meter.  as you brake the meter moves into the charge section.  The further into the charge sector the more regeneration is created.  When you hit max regen the mechanical brakes start to operate.  I have a Corolla but it must be the same for all Toyota hybrids.

[MikeSh]

1 hour ago, TonyHSD said:

When slowing down with hybrids you can use the brakes as hard as you wish and you still gonna have full regen benefits

Sorry but that's just wrong.

The car has X amount of kinetic energy and if you can get to near stopped using regen then most of X is pushed into the Battery. If you brake harder then X gets divided between friction brakes and regen so less than X goes to the Battery. The harder you brake the more goes out as heat and less to the Battery.

In an emergency stop you'd probably get about X/100 into the battery.

[TonyHSD]

56 minutes ago, MikeSh said:

Sorry but that's just wrong.

The car has X amount of kinetic energy and if you can get to near stopped using regen then most of X is pushed into the battery. If you brake harder then X gets divided between friction brakes and regen so less than X goes to the battery. The harder you brake the more goes out as heat and less to the battery.

In an emergency stop you'd probably get about X/100 into the battery.

Maybe it’s wrong , but I have experienced it’s right. 
When the actual brakes engaged when you slow down sharper you don’t loose any regen but actually you maxed out and any extra stopping power comes on top from the actual brakes as friction and accumulated heat. 
Anyone if in doubt can test and see and hear it for themselves .
Do two hard brakes in 400 meters and your Battery will top up full.
Do prolong brakes and you won’t put as much energy  as when hard braking. Often people who dive more spirited can achieve better average efficient because they add more power to the Battery and then they can use this energy to extend their ev time. If you drive very slow trying to be gentle on both accelerator and brakes you won’t achieve much because you will reduce ev time, the free rolling which is the most important for greater mpg. 
Unnecessary hard acceleration and hard braking will kill this free rolling and reduce efficiency. Moderate with anticipation and free rolling is the way to go. Everyone free to think and believe otherwise. We all have our different views and experiences so no need always to match. 👍

[Lawnmowerman]

On 8/31/2023 at 11:43 PM, anchorman said:

Trouble is the Atkinson cycle doesn’t lend itself to engine braking so despite it connecting directly to the epicyclic box, it can’t generate much retardation.

Hi Don - interesting. I know my RAV4 PHEV was Atkinson cycle but understood my YC was not.

Where did you get your information?

Cheers

[Cyker]

All the Toyota hybrids have been Atkinson/Miller-cycle since the original one, although the newer ones (Mainly the Dynamic Force-branded engines)  can switch between that and normal Otto-cycle mode at will, which is partly why they feel so much more powerful when given the eponymous beans (Albeit at the cost of mpg!)

 

[CPN]

On 9/1/2023 at 9:11 PM, dannyboy413 said:

What OBDII reader would you recommend? For the money, the 'Veepeak' seems to get some good reviews.

https://www.amazon.co.uk/Veepeak-Bluetooth-Scanner-Automotive-Diagnostic/dp/B011NSX27A/ref=sr_1_8?keywords=obd2+bluetooth&qid=1693598446&sr=8-8

OBDLink LX without question. Yes, I know it's among the most expensive but I have tried 2 cheap options and they were useless as they couldn't keep up with the polling/scanning rate required by HA. I would put the Veepeak that you cited in the same category as these.

I also used a Carista for a while which is better but again, eventually, it can't keep up.

OBDLink takes it all in its stride. It's also the one that uses the least standby current (when it goes to "sleep") so can be left plugged in without the danger of it draining the 12v Battery.

Note: Torque and Torque Pro do not place the same kinds of demands on the OBDII scanner as Hybrid Assistant which monitors multiple PIDs simultaneously in real-time - and is why OBDLink LX & MX wins every time.

[YarisHybrid2016]

Max regen yes, max recuperated energy, no. That's what @MikeSh is trying to say.

Any energy dissipated by the brakes is lost.

It's best to use moderate regen-only braking for as long as possible, to capture as much energy into the Battery as possible (two bars).

If you're going down-hill with the limiter ON, and you're bouncing off the limiter itself, cancel it and manually brake, otherwise the limiter will just use minimal regen and spin the engine, losing an opportunity to put charge in the Battery.

Use of B mode must also be done sparingly, as it too spins the engine, losing energy.

The more charge is in the Battery, the harder the brake pedal becomes.

[CPN]

50 minutes ago, YarisHybrid2016 said:

Use of B mode must also be done sparingly, as it too spins the engine, losing energy.

Contrary to popular opinion, when in B mode the HV battery does receive some charge from the effect of regen braking while slowing down.

This can be seen in reality when using Hybrid Assistant on the move... (which shows clearly on the power gauge to the extreme right and shows both energy in (charge) and energy out (discharge) of the HV battery)