I’m a Model 3 reserver, first time owner, taking delivery in Late 2018. I test drove a Model S twice since no Model 3’s were available. The 1st time was a real thrill! The 2nd time I waited 2 mos., to let the thrill subside. I was more focused on details then and noticed the drag w/ regenerative braking. It really jerked when I removed my foot from the accelerator. Thankfully, it DID have 3 regen braking settings. The default was not so good - had more drag than my current ‘08 Camry Hybrid. The Model S “lighter” setting was not as noticeable/better. I’m hoping that the Model 3 regen braking (“drag” as I call it) will be acceptable. Ideally, it would be great to have 3 regen settings as in the S. Any Model 3 owners, please send your thoughts on the regen braking.
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Regen Braking Preferred 3 settings.
- Thread starter LTLT
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- Driving Dynamics Model 3
If regen bugs you (lots of EV folk love regen), you need an EV with blended brakes. In normal mode, it will feel like a car with an automatic transmission in D. The regen is still there, it's just part of the braking system. It hides it. The first 60-70kW of retard when you hit the brakes is regen. If you hit the brakes harder, it starts to use the rotors and pads to burn off energy like an ICE car. The brakes are seldom used. 60kW is enough retard to cover most driving in a 3700lb car.
ie - an EV with blended brakes feels like an ICE or cheapo hybrid system, but still has great city range because it hides all of it's regen.
The best blended braking requires FWD/AWD since ~70% of your braking power comes from the front tires.
PS - The reason you can't feel regen in 2008 Camry Hybrid is because the electric motor is tiny. It applies very little regen at all relatively speaking. That's why it's city economy isn't exactly stellar for a hybrid. A hybrid with serious regen and blended brakes acts just like the Camry compliance edition, but has about double the city MPG.
PSS - One Foot Driving is Fun once you get used it. This occurs on EVs with high regen. When you lift the pedal on the right, it will come to full stop.
ie - an EV with blended brakes feels like an ICE or cheapo hybrid system, but still has great city range because it hides all of it's regen.
The best blended braking requires FWD/AWD since ~70% of your braking power comes from the front tires.
PS - The reason you can't feel regen in 2008 Camry Hybrid is because the electric motor is tiny. It applies very little regen at all relatively speaking. That's why it's city economy isn't exactly stellar for a hybrid. A hybrid with serious regen and blended brakes acts just like the Camry compliance edition, but has about double the city MPG.
PSS - One Foot Driving is Fun once you get used it. This occurs on EVs with high regen. When you lift the pedal on the right, it will come to full stop.
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swaltner
Active Member
Not to say they can’t improve the vehicle by implementing this, but I don’t think this is as desirable as you think it will be. Coming from vehicles with automatic transmissions, most drivers are lazy and simply just take their foot off the accelerator pedal when slowing down. When switching to an EV, you quickly switch to where you feather the pedal to provide the exact amount of electric power desired at that point from full acceleration to full deceleration. It takes just a little time to develop the habit of applying a little throttle before disconnecting the cruise control - not enough to start speeding up, but keeps you from switching to full regen.
As a snarky college boy, I teased my mom saying that the throttle wasn’t like a toggle light switch, but rather a rheostat (dimmer). This was after she was driving my brother’s car that had a turbo, and hearing the turbo spool up and down, thought there was a police car in the area.
As a snarky college boy, I teased my mom saying that the throttle wasn’t like a toggle light switch, but rather a rheostat (dimmer). This was after she was driving my brother’s car that had a turbo, and hearing the turbo spool up and down, thought there was a police car in the area.
Your problem was that regen braking requires a slightly different mindset to drive. Do NOT remove your foot from the accelerator to slow down. Lift your foot up just a bit and the car will slow smoothly. With a very small amount of practice, you will be feathering the accelerator up and down to the best position for a smooth controlled glide through town, and using the brake only at 1-3 mph as you near a complete stop. This effect is one of my favorite EV attributes--combined with no gear changes, it makes the whole experience smoother than ICE.
Also, just to be clear--I'm using the most aggressive regen setting on the S
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I'd prefer they just give me 2 sliders, like my motorcycle.
I have a slider to control off-throttle (coasting) regen and another to control braking regen. I usually run with 66% regen off-throttle and 100% on braking. I came from mostly manuals, so the transition to the Tesla was pretty smooth, but I can certainly see some people being much more comfortable with 10-20% regen off-throttle and 100% regen once they touch the brake.
Coincidentally, the bike also gives me sliders for max speed and max torque. Would be nice to be able to tie all those settings to a driver profile. Would be fine to leave the current options as default and hide more advanced controls behind an advanced tab.
I have a slider to control off-throttle (coasting) regen and another to control braking regen. I usually run with 66% regen off-throttle and 100% on braking. I came from mostly manuals, so the transition to the Tesla was pretty smooth, but I can certainly see some people being much more comfortable with 10-20% regen off-throttle and 100% regen once they touch the brake.
Coincidentally, the bike also gives me sliders for max speed and max torque. Would be nice to be able to tie all those settings to a driver profile. Would be fine to leave the current options as default and hide more advanced controls behind an advanced tab.
cablue
Member
Many prefer to use the full regen, but my husband does not like it and drives his on the low setting. It's not very noticeable. Using the standard regen takes time to learn how to keep the rear brake lights from appearing every time the foot is released from the accelerator, which can be annoying to the one driving behind the car.
Some finesse required. The pedal controls the speed—push down some to go faster, let up some to go slower, or put your foot at a spot that maintains a constant speed. It’s seamless; there’s no shifting your foot from one pedal to another to inform you when you go from power to braking. Because the motor is always directly connected to the wheels, you won’t readily be able to tell where the transition is.
Remember, just as pushing the pedal to the floor will give you maximum acceleration, releasing the pedal completely will give you maximum magnetic braking (regen). For everything in between, your foot needs to stay on the pedal. Let up a little — less braking; let up more — stronger braking.
3-page tutorial for single-pedal speed control:
http://www.telomeremedia.com/SinglePedalTutorial.pdf
Remember, just as pushing the pedal to the floor will give you maximum acceleration, releasing the pedal completely will give you maximum magnetic braking (regen). For everything in between, your foot needs to stay on the pedal. Let up a little — less braking; let up more — stronger braking.
3-page tutorial for single-pedal speed control:
http://www.telomeremedia.com/SinglePedalTutorial.pdf
insaneoctane
Well-Known Member
I suspect that is a decision to keep the GUI simple. Bozos spoil it for the non-bozos by preventing them from getting the cool stuff
. I'd like a slider AND a higher setting than currently standard.I suspect that is a decision to keep the GUI simple. Bozos spoil it for the non-bozos by preventing them from getting the cool stuff
Can't get too aggressive in a RWD drive vehicle. I'm assuming that will come with AWD.
Does the S have 3 regen settings now? That must have been a very recent software update (or I never look at that screen anymore)
insaneoctane
Well-Known Member
Well most of your weight shifts to the front of the car during braking which is the reason that you find much larger brakes on the front wheels of a car vs the rear. As such, there is only so much braking you can get out of the rear wheels of a vehicle before they overcome traction. This becomes even more true if it's raining as there is less traction afforded the rear tires as weight shifts to the front of the vehicle. In a nutshell, you can be much more aggressive regen braking if you have a motor on the front wheels.
This is all true, but not actually relevant as a limit for EV regen power. The load transfer is a function of the deceleration rate and CG height. A car's brakes are generally sized for rapid stops (~1g), which create the most transfer, hence the larger front brakes on most cars. The other extreme is a slow stop, which has proportionally less load transfer, so during a typical stop (0.1-0.2g) the front and rear tires see very minor transfer and their braking effectiveness is dictated by the static weight distribution to each axle. The max regen seen in EVs is around 0.3g, with the Model 3 having an average of 0.19g in the standard setting.
At such relatively low decelerations and with the low CG from the battery, the load transfer is not a significant factor that would limit regen power. Both FWD and RWD EVs have a very similar ability to create regen power in a stop.
If we assume the Model 3 CG height is 18", the same as the S, then along with wheelbase we can calculate how much load transfer happens as different deceleration values:
Example:
CG height: 18" (est)
wheelbase: 113"
3 LR weight distribution: 48% Front, 52% rear
CG longitudinal position: 59" [113*.52]
Rear wheel load at 1g: (59-18)/113 = 36%
Front wheel load at 1g: 1-.36 = 64%
Rear wheel load at 0.3g: (59-0.3*18)/113 = 48%
Front wheel load at 0.3g: 1-.48 = 52%
So during a hypothetical stop at 0.3g, only 4% of the load shifts forward. Since the Model 3 starts with a 2% rear bias, the load shift to only 2% forward bias.
One more example:
3 SR weight distribution: 47% Front, 53% rear
CG longitudinal position: 60" [113*.53]
Rear wheel load at 0.19g: (60-0.19*18)/113 = 50%
Front wheel load at 0.19g: 50%
For during a standard regen stop in the 3 SR, rear tire load reduces from 53% to 50%.
Ok, one more for giggles:
Jeep Wrangler weight distribution: 50%/50%
CG height: 26" (est)
wheelbase: 95"
Rear wheel load at 1g: (47.5-26)/95 = 23%
Front wheel load at 1g: 77%
insaneoctane
Well-Known Member
With a dual-motor Model 3, it's not a question of FWD vs. RWD, but rather AWD versus RWD. Magnetic/regenerative braking with AWD gives you twice the potential braking power of either FWD or RWD before limits of adhesion are reached.
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