regen braking

[TonyHSD]

Ok, 

just had done an experimental drive in B mode on a flat roads in Watford town  and the car does drive very similar to D but with stronger regenerative braking. And can confirm that the Auris hybrid does drive in B on ev only up to 30 mph like in D and engine doesn’t start all the time also when slowing down does harder in ev only without engine to intervene. I am positive about it as I did on very quiet place and with windows down plus been watching dashboard. The feeling is like driving ev with stronger regenerative braking or been a passenger in my gf car , not very pleasant experience 😂👍

[Cyker]

It's quite interesting the differences - The Mk4 will immediately spin up the engine in B-mode when you lift off at any speed above maybe 5mph-ish?

Like yours, the slow-down is very strong; It's amazing how much retarding force it produces considering no friction brakes are used.

 

[MikeSh]

6 hours ago, CPN said:

Also, it does create "regenerative power" back via MG1.

6 hours ago, CPN said:

if you engage "B", the ICE will always get started up

The engine isn't actually started or running in overrun in B mode. MG1 in conjunction with the road wheels is spinning the (dead) engine at high rpm to create large pumping losses and thus 'engine braking'. As such MG1 is probably consuming some of the power being generated by MG2 since it (MG1) is having to push the engine round against the road wheels to provide the extra 'braking' force.

[CPN]

Well ok Mike, I guess you could substitute...

"if you engage "B", the ICE will always get started up"

with:

if you engage "B", the ICE will always get connected via the power-split device; similar to when the ICE gets started by MG1.

Whether it is "started" and providing power or whether it is spun up against the resistive forces of no spark or injection but compression, the end result will be the same... ie. "engine braking" of a sort.

[TonyHSD]

Good morning, 

just on the way home now on my usual downhill drive I engaged B and let it hold the car at steady speed although the regen was a bit too strong I manage with accelerator slightly depressed and the car maintained constant speeds and slowed down with actual brakes only used just before the junction where the car came to a complete stop and engine shuts off too. Then I selected EV button while still in B mode and continue to my house in ev drive only with B mode selected and no engine interference at all, just like bev with one pedal drive, honestly very strong regen only from the mg2.  Now I can say for sure that not always the engine will engage when selecting B mode.
At lower speeds you can have stronger regeneration without engine running. 
The thing is you need to select B and drive the car in different situations at different speeds, stop , then start moving off the line in B mode to find out if your cars will behave the same way. Flipping to B while driving at 35-40 or 60mph will engage the petrol engine for sure but at lower speeds most likely not always. , I believe yours will behave like mine, I don’t see a reason why should be different. 

[anchorman]

I’m fairly sure the programming won’t be the same as a 2010 and a 2020+.  We’re on version 4-5 now so things might not be the same so I’m not surprised we’re seeing differences.  

[YarisHybrid2016]

@CPN Thanks for testing this!

From what I've seen so far, the Gen.3 spins the engine under braking (I could really wind it up on a short but steep down-hill grade if I braked, but this didn't happen with B mode alone).

Regen braking I think is maximized without brake input (it felt like it, and the needle went deeper into the blue).

The Gen.4 seems to work similarly; just selecting B mode results in maximum regen, and spins the engine under braking.

The Gen.4 gets weird when we start talking cruise control vs. speed limiter.

If the speed limiter is active when going down-hill, and you're at the set limit, it will use minimum regen (1 bar), and spin the engine to maintain speed.

In cruise control however, it seems to be able to use the brakes (and it must in order to come to a dead stop). I haven't heard the engine spin in cruise, but did notice the lack of EV while decelerating quite hard.

For down-hill grades, I kick the limiter off and brake manually in order to benefit from regen.

[MikeSh]

10 hours ago, CPN said:

Whether it is "started" and providing power or whether it is spun up against the resistive forces of no spark or injection but compression, the end result will be the same... ie. "engine braking" of a sort.

Yes. My point really is that we use correct terminology as I have seen (in a previous thread, perhaps not this one) people saying that the engine is started and is somehow driving the extra braking.

[MikeSh]

2 hours ago, anchorman said:

I’m fairly sure the programming won’t be the same as a 2010 and a 2020+.  We’re on version 4-5 now so things might not be the same so I’m not surprised we’re seeing differences.  

From the descriptions given it seems clear that B mode is really only operating with foot off the throttle. As the throttle is depressed it will transition into a 'normal' operation. As you say, how that blending is done is obviously quite different between versions.

[CPN]

Ok, brace yourselves for a long post! A day later than promised but I think I managed to catch some good screenshots from today's journey...

This was just after we had set out 9 miles down the road on a dual carriageway with a 50mph limit... ICE fully warmed up etc. Happily pootling along in EV mode drawing 8.6kW from the HV Battery... (note that HA considers it not ideal though - red highlight for both "EV" and "blob")

Onto the A19 now heading south. Cruise control on at 70mph (note the difference to actual speed). Very little traffic today so far. "Blob" in it's ideal place and colour (between the two power meters to the right - ICE Left, HV Batt right). Note the mpg! (which is instantaneous as opposed to average) ICE providing 12kW (~16bhp) and system feeding back 400w back into the HV.

A bit further and here's an example of what I call "super milk float mode"! Still at the national limit with cruise control on MG1&2 and the invertor fully warmed up now. 300w coming from the HV Battery and the ICE doing its "idle check" thing (it briefly comes up in the piston icon then drops back to 1000(rpm) as you can see (I missed the "idle check"). Flat-level road in effective EV mode not even having to try really. Note the mpg!

~4 miles later and it has finished its "idle check" procedure and the EV has taken over proper drawing 6.7Kw from the HV Batt; ICE shutdown. Good SoC at 61%. (Had to slow down for a lorry...)

Cruising back up to 70 (67 really!) again and this is what I would describe as a more "normal" kind of ideal display from Hybrid Assistant during high-speed cruising. Roughly 15kW combined driving the car (~20bhp) at an excellent 72.29mpg. The "blob" is an ideal green and the HV Battery is starting to warm up a little (centre of the display).

Had to slow for some traffic here. Quite a bit further on in the journey. ICE off, HV chucking out 8.5kW (~11bhp). Again, not ideal but great fuel consumption!

I only included this next one to show the rapid change in HV Batt temperature when there are many speed changes and current flow in/out of the HV Batt...

A bit further on and back to more ideal conditions (green "blob")

Okay, now the interesting bits. This was entering the slip road (mild downhill) coming off the M18 and simply cancelling cruise control... Start of regen braking. 4.8kW (6.5bhp) reverse (power into the HV Batt).

Switched from "D" to "B" (foot off the throttle). Increase to 5.6kW reverse (7.5bhp) but also note the ICE has also gone reverse power to the tune of 11kW reverse (~15bhp)

Just before the end of the journey, I tried to show what the maximum regen braking I could muster from my right foot without bringing in the mechanical brakes (by watching the brake cylinder icon top left of centre - small green blob at the start of 5) and this was the result. It actually jumped to "-22" that I saw but wasn't quick enough to catch it. Even so, -16kW represents ~21.5bhp in reverse. That is some serious regen braking! Also, note the effect on the temperature of the HV Batt of all this. The fan has cut in at its first speed setting at 35°C.

On the way back now and I managed to do better!! 😉

Lots of good green stuff in this one! (good mpg too!)

This is weird! No ICE, and HV being charged! You guessed it cruising downhill!

Stupid idiot cut in front of me here!! However, not "B" mode and note the ICE negative kWs... (but heavy braking of course - combined regen and mechanical)

The best regen (only) that I managed. Slowing down the slip road for the filling station... That's the equivalent of ~35bhp in reverse!

...and finally, this is a special one for @Cyker 😉

"givin' it the beans"!! ...winding up onto the slip road to match traffic speed! That combined 82kW represents 109.964bhp (!!) so I guess Toyota doesn't lie about its platform! 🤣

...and really finally this time, this is to celebrate the milestone my trusty Red Baron passed today! 😁

Enjoy! 

 

[Cyker]

Wow, that's some really good and comprehensive info! Cheers!  

So it seems the regen doesn't get past 6kW in B-mode, but you managed 22kW regen with manual braking? Those are good benchmark figures to compare if someone with an Auris would like to try the same thing!  

Also, I approve of your 5000rpm beans-giving  

 

[MikeSh]

1 hour ago, CPN said:

Cruise control on at 70mph (note the difference to actual speed).

I've found most modern (last decade or so) cars I've driven have driver speedometers that read about 3 mph fast. To comply with UK/EU regs that don't allow any under-reading.

When I set the CC I always aim for about limit +3 (and Google nav generally agrees).

[CPN]

7 minutes ago, Cyker said:

Wow, that's some really good and comprehensive info! Cheers!  

Thank you! 🙂

7 minutes ago, Cyker said:

So it seems the regen doesn't get past 6kW in B-mode, but you managed 22kW regen with manual braking?

Check the screenshot before the beans one, 26kW actually 😇

7 minutes ago, Cyker said:

Those are good benchmark figures to compare if someone with an Auris would like to try the same thing!  

Yes. that would be interesting...

7 minutes ago, Cyker said:

Also, I approve of your 5000rpm beans-giving  

(snigger...)🤩

[CPN]

1 minute ago, MikeSh said:

I've found most modern (last decade or so) cars I've driven have driver speedometers that read about 3 mph fast. To comply with UK/EU regs that don't allow any under-reading.

When I set the CC I always aim for about limit +3 (and Google nav generally agrees).

Indeed. That's how I usually set it myself...

[MikeSh]

3 hours ago, CPN said:

Indeed. That's how I usually set it myself...

Any particular reason why not in this case?

[CPN]

10 minutes ago, MikeSh said:

Any particular reason why not in this case?

No particular reason. Just set it to 70 knowing that it would show the real speed on HA... I suppose to highlight the over-read of the dash...