ALAW

Paddle shifters Re gen braking power

Recommended Posts

Before i purchased the UX i watched a lot of you tube videos. One of them specifically mentioned using the steering wheel paddle shifters to achieve re generative braking putting power back to the vehicle. Got to be honest i didnt have a clue. My dealer when asked was a bit sceptical. On another thread on the UX forum i can see some have mentioned about the shifters but not putting energy back to vehicle. Be interested to know what your thoughts are. 

Brent

Share this post


Link to post
Share on other sites

I had a similar question regarding the "B" braking on the transmission of my 400 h. Does using B going downhill increase regenerative braking? Consensus of opinion was that it will only regenerate to a maximum the traction battery will take. Correct me please Colin, if I have got this wrong.

Share this post


Link to post
Share on other sites

The paddle-shifters in the UX250h simply force the transmission to run the engine in a higher rev-range, creating engine braking. It doesn't affect how much energy the electric motors can capture, and in fact wastes a bunch of energy as heat and noise. A far better idea is to squeeze the brake pedal until you max out the "regeneration" indicator on the dash - that's the maximum energy the electric motor can capture - squeeze it further and brake disks come into play, at which point you're once again turning momentum into heat instead. If you can start braking early enough using maximum regeneration you can actually come to a complete stop without using the brake pads at all.

I understand that the "B" mode simply increases the amount of automatic regeneration that the motors apply when you release the accelerator peddle, even before you touch the brake. It means you can't coast as well, so not as efficient in many cases, and probably why Lexus stopped putting a "B" mode on their newer models.

Hope that helps!

Nick

Share this post


Link to post
Share on other sites

If you can start braking early enough using maximum regeneration you can actually come to a complete stop without using the brake pads at all."

 

And that is how Tony Richa,  a former Member was able to obtain 200,000 miles from brake pads/Disks.

Make one ponder eh ?

Share this post


Link to post
Share on other sites

*low whistle*

Honestly? I'd love it if Lexus could find a way to wildly increase the amount of regeneration braking the motor could provide to the point where you'd only need pads to hold the car at a stand-still. Time to go read up on how alternator/generators work...

Nick

  • Like 1

Share this post


Link to post
Share on other sites

1 hour ago, EvilRacer329 said:

I'd love it if Lexus could find a way to wildly increase the amount of regeneration braking the motor could provide

On the IS300h (and I imagine other Lexuses and Toyotas are similar) the limit doesn't seem to be the motor/generator. I don't know the exact number but on this car MG1 has a capacity of around 40 kw.

The Battery, however, has charge and discharge limits of around 23-25 kw. These numbers vary with temperature and state of charge.

My guess would be that a bigger Battery could take higher charge and discharge rates. (I hope someone will correct this if it's wrong.) If this is the case, to get more regeneration you would need a Battery that was bigger (takes up more boot space) heavier (reduces fuel economy) more expensive (pushes the retail price up). So the current configuration was presumably the best compromise at the time the car was designed. These factors will change as batteries get cheaper, smaller and lighter.

Share this post


Link to post
Share on other sites

This is one area where I prefer Tesla's approach. The brake pedal solely operates the friction brakes. All acceleration and regen braking is handled by the throttle pedal.

Take your foot off completely and you have maximum regen. If needed, supplement with the brake pedal if extra deceleration is required. Almost allows for one-pedal driving.

 

Share this post


Link to post
Share on other sites
44 minutes ago, Thackeray said:

My guess would be that a bigger battery could take higher charge and discharge rates. (I hope someone will correct this if it's wrong.)

It's not the actual size of the Battery as such, although as you say a bigger one could probably take more, but rather the rate of charge.

Squirt too much power in at one go and any Battery will be damaged, so the charging rate is limited.

Share this post


Link to post
Share on other sites

Ah, that makes a lot of sense - thanks, Thackeray/Herbie! It figures that the limit is the Battery's charge rate rather than the amount of load/electricity that the generator can, well, generate. I gather that one of the reasons Lexus/Toyota are still using Nickel-Metal Hydride batteries is because their fast charge/discharge rates are slightly better than lithium ion, even though they're less energy dense and heavier as a result.

I didn't realise that Teslas had no coast mode - can you adjust the level of automatic regenerative braking in case you want to coast etc.?

Nick

  • Like 1

Share this post


Link to post
Share on other sites
4 hours ago, EvilRacer329 said:

I didn't realise that Teslas had no coast mode - can you adjust the level of automatic regenerative braking in case you want to coast etc.?

You can adjust it - there is the option of "normal" off-throttle deceleration to mimic regular automatic cars or enhanced regen that gives you more off-throttle decel.

These were the two options in the Model S that I drove a while back, although it could have changed since with subsequent OTA updates. Either way, there is no blending of regen braking with friction braking on the brake pedal.

Share this post


Link to post
Share on other sites
16 hours ago, Spacewagon52 said:

I had a similar question regarding the "B" braking on the transmission of my 400 h. Does using B going downhill increase regenerative braking? Consensus of opinion was that it will only regenerate to a maximum the traction battery will take. Correct me please Colin, if I have got this wrong.

B mode does increase the amount of regen braking when you come off the accelerator, so you feel more deceleration than normal but this isn't anything more than you could achieve yourself by lightly pressing the brake pedal.

The main purpose of B mode is at higher speeds. To provide a braking effect the system engages the petrol engine so the wheels are effectively spinning the engine over creating a load, because the regen system cannot convert enough kinetic energy into electrical energy on its own (either because the generator isn't powerful enough or the hybrid batteries cannot take the current). The engine isn't providing any power, it is shut down with no fuel being injected or plugs sparking. This stops the mechanical brakes needing to be engaged, and potentially overheating, and is really only intended down a very long and steep hill where you would otherwise accelerate away.

The fact that the mechanical engine is being made to spin, producing heat and noise, means it is less efficient than normal mode and why it shouldn't be used more than necessary.

If the vehicle has a simulated gearbox then there is no need for a dedicated B mode as using a low gear achieves the same thing - so in the current range of Lexus vehicles only the CT200h has a B mode. 

Share this post


Link to post
Share on other sites
16 minutes ago, ColinBarber said:

B mode does increase the amount of regen braking when you come off the accelerator, so you feel more deceleration than normal but this isn't anything more than you could achieve yourself by lightly pressing the brake pedal.

The main purpose of B mode is at higher speeds. To provide a braking effect the system engages the petrol engine so the wheels are effectively spinning the engine over creating a load, because the regen system cannot convert enough kinetic energy into electrical energy on its own (either because the generator isn't powerful enough or the hybrid batteries cannot take the current). The engine isn't providing any power, it is shut down with no fuel being injected or plugs sparking. This stops the mechanical brakes needing to be engaged, and potentially overheating, and is really only intended down a very long and steep hill where you would otherwise accelerate away.

The fact that the mechanical engine is being made to spin, producing heat and noise, means it is less efficient than normal mode and why it shouldn't be used more than necessary.

If the vehicle has a simulated gearbox then there is no need for a dedicated B mode as using a low gear achieves the same thing - so in the current range of Lexus vehicles only the CT200h has a B mode. 

Thanks Colin that explains it clearly. Hence why the handbook (yes John!) says do not leave the car in B or economy will suffer! 

Share this post


Link to post
Share on other sites

Well some interesting replies here thanks. So reading your threads have i interpreted correctly by thinking the paddle shifters change the revs, and by simply easing off the accelerator or taking the foot off completely especially going downhill (like you would get going to Cornwall down the A30) . This would put regen energy back into the Battery and you would be travelling in EV mode. This B mode thing confused me at first i thought is it braking. Colin then mentions this B mode is only available on the CT. So it isnt on the UX. By the way i have a confession i never use the paddle shifters and i never did in the Audi. Do you think i should.

Brent

Share this post


Link to post
Share on other sites

My usual rule is, going downhill, to keep braking in regen zone tilll Battery is fully charged and only after using  lower gear (RX has gear selection).

If I don't care about charging to the max, I set the adaptive cruise control to max speed (less about 5 mph) and it automatically shifts gear. 

Share this post


Link to post
Share on other sites

The only way the paddles on the UX make sense to me is in conjunction with both the shifter and engine mode set to "Sport". Then, the transmission behaves like an automated-manual, allowing you to shift at will and keep the revs high for fast driving. It does make the car more responsive, because there's instant power when you ask for it, as there's no delay while the engine spools up, but it's obviously very thirsty. Something I tend to do only on very twisty roads, for fun. In day-to-day the car is left in "Normal" mode.

Fascinating stuff about "B" mode, I'm happy to be wrong on that one and am now no longer annoyed that my car lacks it! 🙂

Nick

Share this post


Link to post
Share on other sites
On 10/15/2020 at 12:13 PM, royoftherovers said:

If you can start braking early enough using maximum regeneration you can actually come to a complete stop without using the brake pads at all."

 

And that is how Tony Richa,  a former Member was able to obtain 200,000 miles from Brake Pads/Disks.

Make one ponder eh ?

It does indeed Roy!

I've been using the Hybrid Assistant app on all trips recently and I beat myself up if the brake indicator turns red instead of green - this means that I'm using the mechanical brakes and not regeneration, and thus burning money!

  • Like 1

Share this post


Link to post
Share on other sites
24 minutes ago, Mincey said:

I've been using the Hybrid Assistant app on all trips recently and I beat myself up if the brake indicator turns red instead of green - this means that I'm using the mechanical brakes and not regeneration, and thus burning money!

Have you looked at its partner app Hybrid Reporter? This gives an extensive report of statistics for each trip. For example, as a brief snippet from a trip report here's a chart showing the number of brake events during a trip:

Brakings 59
Good Brakings 52
Bad Brakings 4
Mixed Brakings 3
Braking Efficiency 90.68 %
Braking while moving 10%
Longest brake event 0:26 sec
Total energy recovered by braking 0.554 kWh

It will even produce a street map showing where you braked, where you accelerated and where you coasted.

Share this post


Link to post
Share on other sites
3 hours ago, Thackeray said:

Have you looked at its partner app Hybrid Reporter? This gives an extensive report of statistics for each trip. For example, as a brief snippet from a trip report here's a chart showing the number of brake events during a trip:

Brakings 59
Good Brakings 52
Bad Brakings 4
Mixed Brakings 3
Braking Efficiency 90.68 %
Braking while moving 10%
Longest brake event 0:26 sec
Total energy recovered by braking 0.554 kWh

It will even produce a street map showing where you braked, where you accelerated and where you coasted.

Wow! Technology is wonderful BUT ........ it explains why the internet keeps sending me adverts for Viagra? How do they KNOW? It must be an APP on my phone I am not aware of!

Share this post


Link to post
Share on other sites
3 hours ago, Thackeray said:

Have you looked at its partner app Hybrid Reporter? This gives an extensive report of statistics for each trip. For example, as a brief snippet from a trip report here's a chart showing the number of brake events during a trip:

Brakings 59
Good Brakings 52
Bad Brakings 4
Mixed Brakings 3
Braking Efficiency 90.68 %
Braking while moving 10%
Longest brake event 0:26 sec
Total energy recovered by braking 0.554 kWh

It will even produce a street map showing where you braked, where you accelerated and where you coasted.

Oh now then. I am filled with data based lust - I need this, I need it now!

Share this post


Link to post
Share on other sites

If you don't mind me joining this topic even though my car has yet to be delivered! I was wondering if you were in cruise and then started going down hill, normally your momentum would held back by the cruise mechanism to stop your speed increasing. Is this the same as braking i.e. you are recharging the batteries at this point? Thanks. . 

Share this post


Link to post
Share on other sites

Yes. About hybrid assistant , the latest update has hybrid reporter inside, no need to download it separately.

  • Thanks 1

Share this post


Link to post
Share on other sites

I'm not finding these apps on the apple App Store - are they Android-only programs?

Nick

Share this post


Link to post
Share on other sites
22 hours ago, Zotto said:

About hybrid assistant , the latest update has hybrid reporter inside, no need to download it separately.

Thanks for that update. I've now spotted that you recommended Hybrid Assistant a couple of years ago. If you're in Italy do you have any connection with the developers? You mention an Italian forum that's connected with its development. (I realise that Italy is a big country and asking if you know the developers is a bit like when I visit America and Americans ask me if I've met the Queen. )

Share this post


Link to post
Share on other sites

About developers, yes, they are active in italian forum Hybrid Synergy Forum, and I appreciate very much their work because they created this app totally for free and they continue developing it for new car models. You can find many suggestion there for best driving of hybrids.

I am member of forum also.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.