Regenerative braking

[drtimhill]

Hey, I currently have a MY for overnight test drive..... I feel the same way about the regen, it made me slightly seasick (and I don't easily get seasick) It absolutely has to do with easing off the acceleration pedal instead of letting it go as in ICE cars and glide the car..... this just isn't the case.... of course, if I switch to Creep mode, everything is fine. Something I guess I'll have to learn (or relearn)

My questions are...

If you just ease off the pedal to slow down or come to a stop, don't you loose the benefit of regen?
How long did you all take to adjust to this before it becomes natural and you are stopping as normally?

-- No, the car has to recover the same amount of energy regardless of the strength of the braking effect. No doubt there is an optimum braking speed to recover the most energy, but frankly I doubt if it makes a huge difference.
-- It took me about 2 days to get used to it, and a few more days for it to become totally automatic.

A few people have reported the "seasick" effect here, and I suspect they are just lifting off the accelerator pedal all at once, which I'm sure would make me feel the same way. The trick, of course, is to gradually lift your foot up and modulate the amount of regen in the same way you modulate braking (though of course it takes a little getting used to).

Once you master it (and it really isnt that hard), you will really love the ease of one-pedal driving. And your brakes will last forever

 

[WhyYesPlease]

It took me about 2 days to get used to it, and a few more days for it to become totally automatic.
...
Once you master it (and it really isnt that hard), you will really love the ease of one-pedal driving. And your brakes will last forever

I agree.

 

[Rshephorse]

Hey, I currently have a MY for overnight test drive..... I feel the same way about the regen, it made me slightly seasick (and I don't easily get seasick) It absolutely has to do with easing off the acceleration pedal instead of letting it go as in ICE cars and glide the car..... this just isn't the case.... of course, if I switch to Creep mode, everything is fine. Something I guess I'll have to learn (or relearn)

My questions are...

If you just ease off the pedal to slow down or come to a stop, don't you loose the benefit of regen?
How long did you all take to adjust to this before it becomes natural and you are stopping as normally?

No, if you ease off the pedal Veeeerrrrrry slowly you can see that they car is in fact coasting, no regen or energy use, [watch the bar in the display] technically yes, you regen less, but my guess is that the new energy use is about the same. You can mimic shifting a car into neutral that way.

I think that learning to drive the Tesla with Standard [max] Regeneration and Sport Mode [in PUP] is just like learning to drive other cars. There are lots of diff't cars to drive that behave differently than a well behaved modern automatic: - old cars with no synchros that you have to rev match, cars with huge turbo-lag, cars where all the power is at really high rpm's.... that's the fun of driving.

People who complain about how the regeneration feels are essentially saying "I don't like the way I drive, and I'm not willing to work on it." It IS really different though, but after awhile you dial it in, can accelerate and decelerate with the rest of traffic. The real fun is driving aggressively but never having to use your brake!

 

[jeffbco]

In almost 20 years of participating in automotive forums, Tesla is the first one I've seen where maladies such as motion sickness and ear pressure problems have been topics of discussion. Maybe we'll start to see more reported evidence of Tesla-induced mental illness such as the OCD nature of new or prospective Tesla owners

 

[spokey]

Hey, I currently have a MY for overnight test drive..... I feel the same way about the regen, it made me slightly seasick (and I don't easily get seasick) It absolutely has to do with easing off the acceleration pedal instead of letting it go as in ICE cars and glide the car..... this just isn't the case.... of course, if I switch to Creep mode, everything is fine. Something I guess I'll have to learn (or relearn)

My questions are...

If you just ease off the pedal to slow down or come to a stop, don't you loose the benefit of regen?
How long did you all take to adjust to this before it becomes natural and you are stopping as normally?

I suspect easing up is better regen (but have no facts to convince anyone). I'm guessing more goes in to regen on a slow deceleration and less in to heat.

I pretty much had standard regen by the time I drove mine home. But I'm used to manuals and even with automatics, easing up to a light pretty far out to get the best gas mileage so that practice probably helped. The only time I use the brake now is for a sudden maybe traffic light change or when regen is limited (haven't gotten that down yet).

 

[origingalatic]

In almost 20 years of participating in automotive forums, Tesla is the first one I've seen where maladies such as motion sickness and ear pressure problems have been topics of discussion. Maybe we'll start to see more reported evidence of Tesla-induced mental illness such as the OCD nature of new or prospective Tesla owners

it's already happening on another thread..... btw, that's because Tesla is the only vehicle that goes from 0-60 in ~4s with ZERO lag. My kids tell me it feels like riding a rollercoaster... I'm sure you all know what I mean.. This is why we buy right? RIGHT?!

 

[origingalatic]

I'm happy to report that in my 2nd day of driving MY, it's already improved quite a bit. Either I've grown numb to it or my superior driving skills retained through middle age....

 

[hgmichna]

I suspect easing up is better regen (but have no facts to convince anyone). I'm guessing more goes in to regen on a slow deceleration and less in to heat.

I pretty much had standard regen by the time I drove mine home. But I'm used to manuals and even with automatics, easing up to a light pretty far out to get the best gas mileage so that practice probably helped. The only time I use the brake now is for a sudden maybe traffic light change or when regen is limited (haven't gotten that down yet).

I'm with you. Have even owned a vehicle with unsynchronized manual gear shift.

Your guess is almost certainly correct. It just doesn't make a big difference, because the electronics are very efficient these days. Still I find myself switching off autopilot/TACC well in time before a stop, so I can very gently reduce the speed, aiming partly for that tiny bit of energy, but also simply for elegance. I perceive driving constant-speed towards a red traffic light, then braking for the last 50 m = 150 ft as decidedly inelegant. Every kind of acceleration change should be slow and gentle.

 

[TIppy]

Because of the 85% round trip efficiency of battery energy storage, it is better to coast to a stop rather than regen for speeds below 45 mph. The problem is that it takes 1.7 km (1mile) and 189 seconds to coast to a stop from 45 mph. So if we want to start to slow down closer to the destination, we must provide some additional retarding force, brakes or regen. Obviously regen is preferred. The longer we wait to begin the stop the more regen is required and the less efficient the stop is. But still much better than using brakes.

The internal resistance of the battery pack is about 0.05 ohms. If we use the average voltage of the pack, 350 v, 60 kw of regen is about 171 amps across the resistance of the pack. The i-squared-r loss is 1.46 kw which is about a 2.4% loss. At 20kw of regen it's about 0.8% loss. There are, of course, other sources of resistance in the electric drive circuitry.

 

[origingalatic]

Because of the 85% round trip efficiency of battery energy storage, it is better to coast to a stop rather than regen for speeds below 45 mph.

So ease off the pedal slowly than to let go completely is better for efficiency. Did I get that right?

 

[TIppy]

So ease off the pedal slowly than to let go completely is better for efficiency. Did I get that right?

Yes. If you start to slow down earlier, you will let off the pedal more slowly to come to rest at your destination.

 

[Farmer]

Steady driving is always more efficient than stop and go. In an ICE, all the stopping the brakes do represents lost energy. In an EV, regen captures and returns the bulk of the kinetic energy back to the car upon re-acceleration, but round trip efficiency is not 100%. Even in an EV, it pays to let the car roll as much as possible rather than actively slow the car down. Anticipating stops and slowdowns as much as possible by letting off the accelerator when applicable gains efficiency in either type of vehicle, if and until EV regen/acceleration efficiency gets to 100%, which, of course, it never really will.

I love regen, but it will never be "perfect."

 

[hgmichna]

So ease off the pedal slowly than to let go completely is better for efficiency. Did I get that right?

Yes, a little bit better.

 

[spokey]

best in my opinion is a very gradual slow down way before the light. Easiest on local roads you know. I try to time the light so I slow down at a steady rate just enough to give the light time to turn green. So if I see a light turn up ahead maybe I'll slow from 45 to 40 or even 35 to hit that light at the max. The goal of course being to minimize the acceleration afterwards.

 

[spokey]

I'm with you. Have even owned a vehicle with unsynchronized manual gear shift.

Your guess is almost certainly correct. It just doesn't make a big difference, because the electronics are very efficient these days. Still I find myself switching off autopilot/TACC well in time before a stop, so I can very gently reduce the speed, aiming partly for that tiny bit of energy, but also simply for elegance. I perceive driving constant-speed towards a red traffic light, then braking for the last 50 m = 150 ft as decidedly inelegant. Every kind of acceleration change should be slow and gentle.

My '63 bug was wasn't a synchronized transmission. The fun part was not using the clutch at all. I found the up shift in that car was pretty easy. The down shift was harder with reving until you matched the engine to the tranny.

 

[hgmichna]

My '63 bug was wasn't a synchronized transmission. The fun part was not using the clutch at all. I found the up shift in that car was pretty easy. The down shift was harder with reving until you matched the engine to the tranny.

I once had to drive with a broken, always engaged, clutch. Luckily I had also trained that.

Had to accelerate from standing in first gear, using the starter, so during the first few seconds it was like an electric car. I got home.

The car was a second world war military Volkswagen (Kübelwagen), later rebuilt into a bus (with wooden floor) in a place called Dessau, East Germany.

 

[Farmer]

I once had to drive with a broken, always engaged, clutch. Luckily I had also trained that.

Had to accelerate from standing in first gear, using the starter, so during the first few seconds it was like an electric car. I got home.

The car was a second world war military Volkswagen (Kübelwagen), later rebuilt into a bus (with wooden floor) in a place called Dessau, East Germany.

I had that happen in a far more modern car. My 1984 VW Rabbit suffered a broken clutch cable sheath once that left the clutch engaged. I did the same thing as you, starting in 1st gear (lucky 1st was very short and the starter had no trouble pulling the car) and shifting on the go. 'Got home okay and the cable was an easy install.

 

[Rshephorse]

I suspect easing up is better regen (but have no facts to convince anyone). I'm guessing more goes in to regen on a slow deceleration and less in to heat.

I pretty much had standard regen by the time I drove mine home. But I'm used to manuals and even with automatics, easing up to a light pretty far out to get the best gas mileage so that practice probably helped. The only time I use the brake now is for a sudden maybe traffic light change or when regen is limited (haven't gotten that down yet).

You might be wrong, I remember seeing a "ramp" protocol for how regen works. Like charging - small amounts of energy are less efficient. Thus, driving in a herky Jerky manner, and taking your foot quickly off the accelerator might be more efficient AND make your passenger sick AND piss off the driver following you. Maybe this will be the Tesla version of the Prius Hypermiler Driver. I've played around with this on a long downhill on my commute- 'coast' when the grade is mild, hard decel when grade is steep = max regen.

 

[Rshephorse]

The opposite is true on the accel side, slow accel to never waste energy....

 

[spokey]

I once had to drive with a broken, always engaged, clutch. Luckily I had also trained that.

Had to accelerate from standing in first gear, using the starter, so during the first few seconds it was like an electric car. I got home.

The car was a second world war military Volkswagen (Kübelwagen), later rebuilt into a bus (with wooden floor) in a place called Dessau, East Germany.

Yeah, that's what I did coming to a light. Got it in to 1rst and let it stall. when the light turned, cranked the starter and off i'd go. Those little bastards couldn't be killed.