Regen Efficiency

[ken830]

gregincal describes it perfectly. Just leave regen on max so that it is always available to you. Then use as much or as little as needed. This will allow you to coast (near zero consumption/regen) for efficiency normally and to avoid the brakes as much as possible when you need to slow down quickly. Best of both worlds.

 

[brianman]

gregincal describes it perfectly. Just leave regen on max so that it is always available to you. Then use as much or as little as needed. This will allow you to coast (near zero consumption/regen) for efficiency normally and to avoid the brakes as much as possible when you need to slow down quickly. Best of both worlds.

With the current implementation of the Model S, I disagree.

If the regen response (and accelerator) was changed from (feeling) very linear to more of an S curve then I'd agree with you.

But as it stands, the zero point ("pure coast") between spend and regen requires a very precise foot and AFAICT there is no physical cue that you're in the "notch". There is the visual cue of looking at the speedometer, but to watch that consistently is unsafe until/unless a heads up display is implemented.

 

[aviators99]

With the current implementation of the Model S, I disagree.

If the regen response (and accelerator) was changed from (feeling) very linear to more of an S curve then I'd agree with you.

But as it stands, the zero point ("pure coast") between spend and regen requires a very precise foot and AFAICT there is no physical cue that you're in the "notch". There is the visual cue of looking at the speedometer, but to watch that consistently is unsafe until/unless a heads up display is implemented.

There's certainly the "seat-of-the-pants" physical cue. It has become second nature to me. I hope they keep it the way it is.

 

[ken830]

With the current implementation of the Model S, I disagree.

If the regen response (and accelerator) was changed from (feeling) very linear to more of an S curve then I'd agree with you.

But as it stands, the zero point ("pure coast") between spend and regen requires a very precise foot and AFAICT there is no physical cue that you're in the "notch". There is the visual cue of looking at the speedometer, but to watch that consistently is unsafe until/unless a heads up display is implemented.

There can not be a notch, because the pedal position for "0 Wh" will vary with speed and terrain. At a stand-still, the "0 Wh" point is at the full-off position, but coming down a hill, it's somewhere in the middle. You just drive by feel and a few glances at the display should be good enough. I can do pretty darn well without ever really even looking down at the display, but if I really concentrate, I can get the "needle" to disappear for a good amount of time (no orange or green at all)...

 

[brianman]

There can not be a notch, because the pedal position for "0 Wh" will vary with speed and terrain.

I'm not saying at a fixed location. I'm saying at an appropriate, dynamic location. Just like with an ICE when you are in the sweet spot of a gear.

 

[wycolo]

1. *Never* use brakes, they just heat the geosphere. Use regen as needed to keep air losses down (speed under 40mph max going down mountain grades) and to keep from crashing car.

2. Going over the higher pass instead of a lower pass 'comes out the same' simply because your average speed is (usually) less doing the higher pass (due to narrower twistier roads or rubbernecking).

3. Cc is your friend going uphill. You notch it down as the grade gets steeper.

4. Cc used downhill only at highway speeds 55+.
--

 

[montgom626]

But as it stands, the zero point ("pure coast") between spend and regen requires a very precise foot and AFAICT there is no physical cue that you're in the "notch". There is the visual cue of looking at the speedometer, but to watch that consistently is unsafe until/unless a heads up display is implemented.

I also use my other senses to guide my foot. I find one pedal driving to be easy and precise.

 

[Ditpixs]

Just to muddy the waters a bit, I'll toss this out...

While regen recaptures energy back into the battery, it also causes increased tire wear which contributes (according to my service manager in Fremont) to the rear tires on the 21" rims only lasting 6-8k miles. At $700/pair, I am reasonably certain that the cost of the energy sacrificed to heat when using the brakes instead of regen is much smaller.

Since Tesla covers the brakes under maintenance and not tires, it makes sense to me to use the brakes as much as possible to reduce tire ware unless I am concerned about range and really need to get every mile out of the pack.

Am I missing something with this logic?

 

[Zextraterrestrial]

Just to muddy the waters a bit, I'll toss this out...

While regen recaptures energy back into the battery, it also causes increased tire wear which contributes (according to my service manager in Fremont) to the rear tires on the 21" rims only lasting 6-8k miles. At $700/pair, I am reasonably certain that the cost of the energy sacrificed to heat when using the brakes instead of regen is much smaller.

Since Tesla covers the brakes under maintenance and not tires, it makes sense to me to use the brakes as much as possible to reduce tire ware unless I am concerned about range and really need to get every mile out of the pack.

Am I missing something with this logic?

yes.

brakes increase tire wear just the same as regen

+ I have over 6000 miles driving my 21" tires extremely hard and they are still good for at least 3k miles (200$ at sears per tire)

+ brake pads are cheap and easy to replace

& the car is evenly balanced so the front tires will wear more if you use brakes vs regen (but is should all balance out, as stopping is stopping regardless of how you do it the tires should wear the same overall)

 

[Ditpixs]

Thanks :redface: - that makes sense... maybe it was more that suddenly lifting off the accelerator vs a gradual movement took a hit like sudden braking. It also might have been an attempt to make me feel better about needing tires every 3 months

I am going to try changing to low regen for my 100 mile commute and see what the numbers look like.

If you can PM me the link to those tires it would be great. The only ones I can find at Sears are not Z rated.

Thanks
Aaron

yes.

brakes increase tire wear just the same as regen

+ I have over 6000 miles driving my 21" tires extremely hard and they are still good for at least 3k miles (200$ at sears per tire)

+ brake pads are cheap and easy to replace

& the car is evenly balanced so the front tires will wear more if you use brakes vs regen (but is should all balance out, as stopping is stopping regardless of how you do it the tires should wear the same overall)

 

[lolachampcar]

http://www.tirerack.com/tires/TireSearchResults.jsp?width=245/&ratio=35&diameter=21
a MS owner on another thread suggested these. He has run them on his SLS with success. Performance was on par with the Pilots while wear was slightly better. The price is fantastic.
Just remember to do all four if changing brands as the traction control will not normally accept two different brands front and rear (rolling diameter issue).

aviators99,
I still can not believe how far the car will coast down making it even harder for me to know that zero consumption spot without looking at the meter. Awesome Cd.

 

[Panu]

Has anyone ever been able to gain range by regen? I've watched my range many times when regen is active and a few times I have lost one km while regen is at 60kW but I have never gained one km.

This guy is driving down a mountain for almost 4km and gains 0km range:

A Tesla In ICEland - Autopilot slowing the car down automatically in tight curves - YouTube

 

[yobigd20]

Has anyone ever been able to gain range by regen? I've watched my range many times when regen is active and a few times I have lost one km while regen is at 60kW but I have never gained one km.

This guy is driving down a mountain for almost 4km and gains 0km range:

A Tesla In ICEland - Autopilot slowing the car down automatically in tight curves - YouTube

yes i've seen my range numbers actually increase, but it took several miles of regen going downhill to do it. also theres a video of a russian guy who towed his MS to the back of a truck and the truck pulled him many miles and his range went up ... here

 

[Cottonwood]

Has anyone ever been able to gain range by regen? I've watched my range many times when regen is active and a few times I have lost one km while regen is at 60kW but I have never gained one km.

This guy is driving down a mountain for almost 4km and gains 0km range:

A Tesla In ICEland - Autopilot slowing the car down automatically in tight curves - YouTube

For some reason, Tesla put in a dead zone of 1 kWh of regen before it shows up in the battery capacity display. This is about 3 rated miles or 5 rated km. That is a lot of regen. For example, driving a few miles over the speed limit from Eisenhower Tunnel to Silverthorne, CO, I can often see two increments (2x3 rated mile) in the battery display, but that descent is about 2,500 feet over about 8 miles.

If you want to see regen on a finer scale, bring up one of the trip displays that shows kWh used. These displays have 0.1 kWh resolution and you can see regen levels that are 1/10 as big.

 

[evp]

For some reason, Tesla put in a dead zone of 1 kWh of regen before it shows up in the battery capacity display. This is about 3 rated miles or 5 rated km. That is a lot of regen. For example, driving a few miles over the speed limit from Eisenhower Tunnel to Silverthorne, CO, I can often see two increments (2x3 rated mile) in the battery display, but that descent is about 2,500 feet over about 8 miles.

If you want to see regen on a finer scale, bring up one of the trip displays that shows kWh used. These displays have 0.1 kWh resolution and you can see regen levels that are 1/10 as big.

I've noticed that too. Longs Peak to I70 jumped about three miles at a time four times. Just what were they thinking? I can't imagine a software design where that behavior would just fall out for free, but I also can't accept that someone did it deliberately.

 

[Cottonwood]

I've noticed that too. Longs Peak to I70 jumped about three miles at a time four times. Just what were they thinking? I can't imagine a software design where that behavior would just fall out for free, but I also can't accept that someone did it deliberately.

Who knows, but it's historic with Tesla. The Roadster has the same behavior...

 

[Polly Wog]

Has anyone ever been able to gain range by regen? I've watched my range many times when regen is active and a few times I have lost one km while regen is at 60kW but I have never gained one km.

@panu, although others have already answered your question, I have additional documented results of the regen capability. See my attached pictures. The first is at the summit of Haleakala on Maui (10,000 feet elevation), the second is at the bottom (about 200 feet elevation). Over the course of 36 miles, I gained 29 rated miles and 8.8 kWh.

 

[benf]

If you can't feel the "sweet spot" in the pedal when you're neither accelerating nor decelerating with regen, just use TACC and it does it for you perfectly. TACC is always going to be more efficient than you can be, so why is anyone even using the pedal at all if they care about efficiency? Am I missing something?

 

[jerry33]

TACC is always going to be more efficient than you can be

This is just not true. It always accelerates and decelerates too hard using more energy than required because it tries to maintain an exact speed rather than vary the speed depending upon conditions. Slowing a bit going uphill and speeding up a bit going downhill do wonders for energy use.

If it was true, then everyone else would be far more efficient than I am.

 

[Shaggy]

We have this lengthy discussion over at Fusion Energi Owners, Fusion Energi Forum as the Energi has a low and high regen from the engine as well as off braking. A guy using the OBD2 port and measuring regeneration, efficiency of either type (brakes, engine), and battery drained determined that the high regen was nice for down hill, but ultimately what made the most difference overall was time spent 'off the battery'. IE. low regen coasting was better on charge & distance as you got off the battery (as a power source) sooner and was able to engine regen and then brake regen to stop if needed better than staying on the accelerator longer (since as soon as you pull off the accel, the car regens stronger) so your stopping distance is shorter. Save for red lights or steeper downhils where the higher regen (or as Ford calls it low gear on a CVT) is better.

If I read correctly the Model S also has 2 levels of regen and the brakes will regen as well, so the above should apply as well. On my Fusion, I can go into high regen quickly by dropping into low gear as on my car it doesn't do anything but increase the regen rate making it FEEL like low gear. How fast can you get into high regen from low regen on the Model S?