06-05-2018, 02:14 PM
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#391 (permalink)
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Master EcoModder
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Right - almost every other EV maker has managed to integrate regen onto the brake pedal. The 2015 Leaf was only noticeable in the transition early on, but it smoothed out after a few thousand miles. All the other EV's I have driven are virtually seamless - e-Golf (excellent), Bolt EV, Leaf, i MiEV (not great brakes) - roughly in order of quality.
The i3 has (by far) the best 1-pedal driving, so I don't think it has regen on the brake pedal; but I could be wrong.
I have driven both a 2nd gen and 3rd gen Prius, and the 2nd gen had noticeable transition, but the 3rd gen was fine.
Batteries only are 100% full briefly. The Bolt EV has an option, called Hilltop Reserve, that stops charging at about 85% full, so that you always have "normal" regen. That could easily be 95% or 98% and it would still do this, for everybody except if you live at the top of a mountain.
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06-05-2018, 02:46 PM
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#392 (permalink)
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Batman Junior
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One reason they may have taken this approach is to avoid the "transition" issues between regen & friction braking on the brake pedal (often described as non-linear and/or grabby). It's a favourite criticism of auto journalists & typical auto enthusiasts.
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06-05-2018, 02:51 PM
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#393 (permalink)
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Master EcoWalker
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Quote:
Originally Posted by NeilBlanchard
"Brake by wire" is not the same as regenerative braking, and that answer conflates them somewhat.
I think it is surprising, and somewhat close minded to not have regen on the brake pedal - and even more so to not have default coasting.
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Actually, not having default coasting compensates for not having regen on the brake pedal.
And does it really not bump up the regen when the brake switch gets activated (long before the pedal gets deep enough to actuate physical braking)?
My Insight does that... Why wouldn't Tesla?
Anyway... Plan ahead to not need (much) braking, if possible. True for almost any kind of vehicle.
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06-05-2018, 04:20 PM
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#394 (permalink)
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Human Environmentalist
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Quote:
Originally Posted by RedDevil
Actually, not having default coasting compensates for not having regen on the brake pedal.
And does it really not bump up the regen when the brake switch gets activated (long before the pedal gets deep enough to actuate physical braking)?
My Insight does that... Why wouldn't Tesla?
Anyway... Plan ahead to not need (much) braking, if possible. True for almost any kind of vehicle.
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The problem with blending mechanical and regen braking is that mechanical begins activating just about immediately since it's a direct hydraulic connection to pads that are already slightly touching the rotors. Perhaps there is a way to engineer dead pedal travel in so that it merely sends a signal to activate regen rather than apply hydraulic pressure to the physical brakes. You'd want mechanical to activate at the point exactly beyond the limits of regen though. Very tricky.
My Prius has smooth brake feel up until the point that it transitions to 100% friction braking, which occurs at <7 MPH.
The slight regen from "coasting" is almost nothing, so it doesn't make up for the fact that braking has no regen capability. On EVs without regenerative braking on the brake pedal, I would use the 1-pedal driving mode to capture as much energy when lifting off the throttle as possible.
Of course, as you say, planning to not use the brakes in the first place always applies.
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06-05-2018, 05:00 PM
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#395 (permalink)
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Master EcoWalker
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There has to be some slack in the pedal or the slightest variance would cause it to brake without it being pressed. In my car there's at least one centimeter of travel between the switch engage (which lights up the brake lights and activates AutoStop when going slow) and detectable physical braking.
I use that to keep rolling towards the end of a traffic jam as long as possible, covering distance for free and hopefully conserving some momentum if everything gets rolling again in time. With AutoStop regen cuts out too
If I go too fast for AutoStop to engage, it will regen more even before the point the brakes grip. That transition is gradual, however, and does not feel unnatural.
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06-05-2018, 05:18 PM
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#396 (permalink)
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Human Environmentalist
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Quote:
Originally Posted by RedDevil
There has to be some slack in the pedal or the slightest variance would cause it to brake without it being pressed.
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The brakes float on the rotors all the time, so there is always some amount of brake drag. The slack in the pedal would be whatever pressure is required to break the static friction of the caliper piston, which is probably not much at all. There may be very little actual braking force when the pedal is slightly depressed, but I don't think it's none.
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06-06-2018, 01:57 AM
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#397 (permalink)
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Master EcoWalker
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Well, there is some slack, or I would not be able to feel and make use of it?
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06-07-2018, 02:15 AM
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#399 (permalink)
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Quote:
Originally Posted by RedDevil
Actually, not having default coasting compensates for not having regen on the brake pedal.
And does it really not bump up the regen when the brake switch gets activated (long before the pedal gets deep enough to actuate physical braking)?
My Insight does that... Why wouldn't Tesla?
Anyway... Plan ahead to not need (much) braking, if possible. True for almost any kind of vehicle.
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Foot off the accelerator, or almost off the accelerator, is when full regen kicks in and the brake light comes on. Below that, the brake light is off and regen drops until you hit a good sized spot for deadband.
The regen's not as strong as the Bolt, but it's still enough for what's effectively one-pedal driving. It starts to decline at about 10mph and completely drops out at <5mph.
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06-07-2018, 11:38 AM
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#400 (permalink)
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Master EcoWalker
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Quote:
Originally Posted by roflwaffle
Foot off the accelerator, or almost off the accelerator, is when full regen kicks in and the brake light comes on. Below that, the brake light is off and regen drops until you hit a good sized spot for deadband.
The regen's not as strong as the Bolt, but it's still enough for what's effectively one-pedal driving. It starts to decline at about 10mph and completely drops out at <5mph.
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That's what I thought I knew about Tesla regen.
One pedal driving means regen must be really strong even without using brakes.
The brakes are not used to save fuel but rather to save on repair bills.
(My comment you referred to was an extension of the description of regen in my Insight btw,)
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.
For confirmation go to people just like you.
For education go to people unlike yourself.
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