I actively dislike pressing the brake pedal anymore, and feel cheated whenever I have to touch it except to activate Hold at a stop.
If supercaps could give me full regenerative braking at 0°F then I’d pay an extra $1-2k for the feature absolutely.
In warm climates I can absolutely see brake pads never being replaced. The only time I use the brake pads to slow down is in sub-freezing temps and once in an emergency.
For those who haven’t driven an EV with strong regen braking, you drive with a single pedal. “Neutral” is the accelerator slightly depressed. Lift your foot to slow down, fully lifting your foot is a strong braking down to about 10 mph. I should look up how fast you get 60-10 with a warm Tesla on regen alone. You drive with a single pedal, and you can dart in and out of traffic very nimbly because over-accelerating for a lane change and then regen’ing back to cruising speed is very efficient and fun and you don’t have to move your foot to another pedal. But regen degrades as the battery cools.
A frozen battery will barely regenerate at all, at 0°F it’s actually disconcerting when you lift your foot and the car just... coasts. The display does have a gauge showing how much regen is available, so it’s not a surprise but it literally feels weird.
Chevrolet used this on the Volt for normal driving, you press the brake pedal and it decides how much hydraulic brakes you need over what regeneration can provide. Audi is going this route too. What makes it even better is they can totally mask the loss of regeneration in cold weather which can be disconcerting.
If anything I think Tesla should make it an option, the loss of regen braking even when the pack is only saturated to 40F is bad enough and just useless below freezing. They can do wonders with OTA so there is no reason to not offer all options, low to regeneration, high regeneration, maximum, and blended.
Again, blended doesn't mean it uses the disc brakes, only that it can when it has too and this is safer than relying on one pedal driving.
Because I don’t want to use the pads, I have to drive a bit differently when less regen is available.
I really like single pedal driving in the first place (see note above about lane changes and such) and I would never want to the pads actuating just from lifting the accelerator.
The only enhancement I would be happy with is full regen under all operating conditions :-)
In 'D', releasing the accelerator coasts; in 'L', it decelerates, presumably subject to the same limitations as the Tesla.
There is also a paddle on the steering wheel which activates regenerative deceleration independent of the brakes. This does not completely stop the car, and has a longer braking distance.
So with the car in 'D' the controls become: press accelerator, go, release accelerator, coast, press paddle, slow down, press brake, stop.
You have to slow down to turn, too. I can't imagine a situation in which you could let speed be outside the driver's control entirely.
a) break yourself on turns, pedestrians waiting, even red light etc.
b) choose to let driver assist take over some of these tasks from you
the whole idea is that instead of doing one-pedal driving on the accelerator it's safer to do one-pedal on the break.
Nondeterministic regenerative braking as described here seems like a serious bug in a vehicle.
I wouldn't call it nondeterministic, there's a notification window alerting you to the limited reg and there's a "gauge" below the "speedometer" that shows power input/output. That being said, it's bad UX/UI and they could do a better job representing it. The power gauge is a hair thin line with no labels or scale that you must intuit the purpose of by observation.
The Gen1 Leaf isn't really better, it's just different. Theere's again a power gauge that shows power input/output. You can clearly see the scale of the gauge which is better but again you must observe it to understand it's purpose. The Leaf also has rings around each tic in the gauge that denotes if that level is accessible. When the batter approaches 100% charge or it's terribly cold you lose rings on the input side of the gauge and when the battery is exceptionally low you lose them from the output side. Again it's nice if you know what it means but the only way to know is through observation of the gauge.
I'm guessing other EVs aren't any better. We're probably going through a phase much like early automobiles where each manufacturer comes up with novel UIs to complete the feedback loop between car and driver. Eventually they'll all standardize on something universally understood.
I would expect the likes of Volvo to make the traditional brakes pull in when regenerative braking lacks power. They tend to have a huge human factors department.
So in your scenario where an individual might need to actively brake, they would be able to without issue. Where it might be an issue is when you're driving in bumper to bumper traffic and you're expecting regenerative braking and it's not there and you roll into the car in front of you. Then again, you don't make it very far down the road without noticing a difference in the accelerator pedal characteristics in limited regen mode.
If so, I think you cannot expect humans (most of them even amateur drivers) to make that switch under stress, no matter how well you signal that the car requires you to use mode B.
Have you driven a standard transmission ICE? Downshifting into a lower gear is a very similar experience to regenerative braking. It's an aggressive deceleration that will slow the car from high speeds but it's no replacement for actual brakes.
For someone inexperienced with an EV, the lack of Regenerative Braking would feel like driving a normal car. For someone familiar with it, you're immediately aware of it's absence. In an ICE you coast by taking your foot of the accelerator, in an EV you coast by applying 10% pressure to the pedal (I made that % up). The reason you need 10% pressure to coast is that anything under that amount is where regenerative braking functions. So there's a weight to the pedal that isn't there when regenerative braking is gone.
It's hard to explain without driving an EV but it would be like using a computer mouse without the scroll wheel. You're keenly aware of it and if it's not there.
Or you could read the LEAF's fine owner's manual. Search for "Power Meter" and it's described perfectly clearly.
That doesn't dismiss the fact that the Power Meter is poor UI/UX.
In most other cars the instrument cluster has clear labels and/or iconography that's identifiable. Even in the Leaf there are signs of thoughtful design, Nissan adapted the standard Fuel Gauge Icon with a Power Plug pigtail to indicate the Battery Level Gauge, though bizarrely it also includes an incorrect port indicator, and they put a battery capacity gauge right alongside the battery level gauge to clearly differentiate the two AND show that they're related.
The Power Meter is fusion of two gauges (i.e. power input/output and available input/output) and there should have been a clearer delineation instead. It's easy enough to infer that the Power Meter is analogous to a Tachometer after observing it for a few minutes but it takes longer to understand the regenerative braking aspect. The disappearing rings based on Temp/Capacity of the Battery are a much harder thing to understand.
But there's definitely a strong correspondence between idiosyncratic experiences, personalities that find such experiences appealing, and personalities that actually buy expensive luxury goods. Most armchair QBs miss that last part.
Someone like you, who would scoff at this weird behaviour, will never buy a Tesla. So why do they care what you think? Some people, the people who actually buy Teslas, talk enthusiastically about the weird behaviours on the Internet, i.e. the most priceless form of viral marketing.
I'm not saying you're right or wrong. That's beside the point. I'm saying you could be right, but you don't really have a solution for, "Idiosyncratic stuff is what payers talk about."
Tesla has always sold itself as having a rapid plan to move from niche expensive luxury good to broad mass market everyman vehicle.
Some Tesla cheerleaders seem to miss that point.
Which may produce enough customers and revenue to make the next refresh less exotic.
Hate to break it to people, but 0-60 times aren't really relevant day to day, and a sub 5 second time in a $50k+ luxury car is not exceptional (the ~3 second times of the bigger models are another story).
I want to say since pony cars came out in the 1960s. Maybe earlier than that.
> Tesla advertised it for their transport truck for crying out loud.
It's actually more of a problem for large vehicles. If your car goes 0-60 in nine seconds instead of four, fine. If your fully loaded truck can't get there in thirty, that's more of a concern.
> Hate to break it to people, but 0-60 times aren't really relevant day to day
There is an onramp to a highway where people drive 75MPH around here. The onramp is a 270 degree spiral that ends in a stop sign two feet ahead of the highway. The highway there goes up a steep hill. People have died. It can be relevant.
You can say the government should fix the ramp, but that doesn't mean they have or will any time soon.
> and a sub 5 second time in a $50k+ luxury car is not exceptional
The whole idea is to get the car with the sub-5 second time below $30K.
When you're buying a high end vehicle "quirky" is the preferred adjective.
20yo $1500 German cars are "unreliable". Chinese EVs are "buggy". When you buy a Tesla, a new high end Mercedes or some other status symbol it's all just part of how it goes. Unreliability or odd behavior is not a negative at that price point. It's all part of the ownership experience. You don't get to complain about it. It's implied by the price point that you knew what you were getting into and can handle it.
A Ferrari might be quirky, a Pagani Huayra might have an endearing decel pop that's unique to it. I have passion and admiration for these exotic cars, so quirks become distinguishing features. A sedan has to get me comfortably from A to B.
In any case, price determines whether technology is given the benefit of the doubt when it fails. Someone breaks a Harbor Freight tool and everyone blames the tool. Someone breaks a Mac or a Snap On and everyone blames whoever broke it. When Walmart has to recall food it's Walmart's fault for not choosing better suppliers. When Whole Foods has to trash a bunch of lettuce people blame the lettuce makers.
When cheap things break, act weird or somehow go wrong they get blamed. When expensive things break or act funny that's how they were meant to be and if you don't like it you were using it wrong or your expectations were wrong. People will do all sorts of mental gymnastics to avoid making expensive things look bad.
This seems safer to me and also easier to control: you press the brake and it brakes. If it can regen, it regens, if not, it uses the disks. If you hit the brakes hard and the regen won't be enough to slow you down, it will use disk to the extent it needs to (or just switch to disk entirely).
Coasting is also good: no reason to regen if what you really want to do is coast, and no reason to have to keep your foot on the accelerator in that case either.
Prius do regen slightly in coasting mode, but it's not very noticeable.
Well, they actually do regen in Drive with the foot off the pedal; the brake pedal engages traditional brakes (with the regen also). Coasting requires slightly engaging the accelerator.
Prius also has an “engine braking” mode (which actually uses either regen or engine braking, depending on hybrid battery charge state) on the shift lever.
> Prius do regen slightly in coasting mode, but it's not very noticeable
The difference between pedal disengaged regen and pedal engages to coast is quite noticeable.
It also makes way more sense: your drivetrain can't be perfectly efficient so being unable to coast (and regen-braking every time you would be) is a double energy loss, first waste energy converting kinetic to electric, then you waste energy again converting back from electric to kinetic.
Regen-braking instead of coasting only makes sense in an "engine braking" analogue: have the car regen-brake to try and keep below some set speed on downhills.
When the battery is full (after descending a long hill) the pre-travel does nothing at all. Of course there's no engine braking during coasting when the battery is full, so you'll know ahead of time.
On newer models, the pedal behaves in the manner you describe.
This is how locomotives implement braking; the drive motor operates in regen and the current goes to massive grid resistors. There are no brake pads.
I kinda wish my ICE car would crank everything up while engine-braking down a hill to reduce brake and fuel use.
It shouldn’t be that expensive...
but in order to warm up the very large battery pack, on a cold morning you need to turn the car on (well) before you start driving to have it warm enough for full regen.
My 15 year old Golf does and engine braking is why I've still got the original brake pads after 180K miles.
This specifically addresses the air brakes you're hearing:
>Dynamic braking alone is insufficient to stop a locomotive, as its braking effect rapidly diminishes below about 10 to 12 miles per hour (16 to 19 km/h). Therefore, it is always used in conjunction with the regular air brake. This combined system is called blended braking.
Large modern locomotives often have "wings" with ventilation slots and fans. That's where the heat from the braking resistors gets dumped. This is a big win when moving heavy freight down long mountain grades. Friction brakes tend to overheat, but fan-cooled resistor banks can dump heat all day.
It's amazing that semiconductors for that kind of power not only exist, but are not that big.
With one counterpoint being that maybe this is a feature, not a bug, and may save drivers from excessive non-productive braking.
For comparison, the Model 3 "frunk" seems to be 28" x 15" x 9" = 3780 cu.in. So you'd have to sacrifice the entire frunk for your resistor pack.
* smaller resistive heaters with higher airflow
* dump the heat into resistively heating the battery. Then use the battery again!
* Just use disk brakes to achieve the same feel. Which is also, basically, dumping heat.
Remember that the problem to solve is that a car shouldn't drive differently at different temperatures...
Heating up the battery with this airflow for a certain amount of time should warm them up relatively quickly and evenly since done via convection too. Now I genuinely wonder if there is a reason why Tesla didn't go with that.
Will make your car prone to fires.
A resistive dump of 20-30 kW would improve the cold weather deceleration experience, but that's a big honking resistor that'd need forced air cooling.
Braking normally goes up to 60 kW. Another 2-4 kW would barely make a difference.
You need the 60kw available for hard braking, but what percentage of the area under the curve is below the 5kw mark?
Hard braking, like slamming them on at 80 mph, can exceed 1000 kW.
For winter, the car is on squishier winter tires. This confuses the traction control unit enough to cut out regen on full pedal lift off and switch over to caliper brakes, still single pedal. The car still slows and comes to a complete stop, but deceleration is much stronger with regen. I've adapted to no longer fully lift off the pedal, expecting a more gentle deceleration, providing a more consistent stopping distance.
The brake pedal still responds normally and it gets used in surprise situations.
Even at -10dC (14dF), the regen operates similar compared to warmer temps with the Leaf. At -30dC (-22dF) the battery heater supposedly kicks in, but have not taken the car into those kinds of conditions. I would think it's a software update on the Tesla to kick on the battery warmers in colder climates for consistent regen. Or software update to engage the brakes when regen isn't available.
Not to mention, it is delusional to consider this style of driving "efficient" because of regeneration. You're paying a premium for acceleration speed, and then being taxed by regneration efficiency...
In addition I like to have some forward movement while changing lanes on a highway, so that if there is someone (several car lengths) behind me in the adjacent lane they know they won’t have to slow down.
So you can add a bit of speed as you make the lane change and then bleed it off in regen to return back to that lane’s cruising speed. It should not be enough of a delta to involve any kind of brake light.
The energy loop is extremely efficient e.g. if you are going 60mph to bump up to 65mph and then back to 60mph, like 90% is reclaimed, from the energy chart display, you get a spike up and then down in consumption whichs appear to be symmetrical.
Actually, if you lane change in AutoPilot I believe it will do something similar. It does not change (semi-)autonomously lanes without applying some power.
After the first replacement I was asked to brake hard periodically to heat the pads. I started doing that, but it did not help much.
I’ve never driven a high performance stick shift, only a cheap beater stick as my first car, but I found high RPM stop and go in 1st or 2nd gear was always somewhat hard work and jerky. The TM3 is absolutely not hard work or jerky, the single pedal driving is actually quite a joy IMO.
The obvious fix is to use that power first for heating the battery. You'd still slow the car via power generation, giving the exact same braking feel.
Trains often do something similar, except that they dump the power as heat to the air. That would work too.
By changing the motor drivers to have a much higher current in all coils of the motor, the I^2 R losses are much higher, and the car will slow down while heating the motors up.
Then run the cooling pumps and the heat will go into heating the battery.
If you regen, you have to slow down, only to have to speed back up again, but at a worse efficiency loss than just coasting.
It's possible to get in an 'envelope' behind another car and get pulled along with it.
So basically like an old pickup from back when 4.xx was a typical rear end ratio and transmissions didn't have overdrive so you were doing 3000+rpm at 60.
It also seems like the first step in the "Okay, we have the basic system that works, lets start knocking off the biggest problems with it." mode that internal combustion cars have been doing for the last 100 years.
Their low voltage also makes them hard to use; you need to balance them, and their capacitances vary considerably. Most range from -20/+80% to -10/+20%, but I guess big customers have options to deal with that. Still, if your battery pack is 300+V, and your supercapacitors can only charge to 3V...that seems difficult.
I used to be really bullish on them for regenerative braking - I think some kinds of buses do use them for that - but having tried to use them, I can't see them being robust enough for consumer, and especially consumer automotive, requirements in the immediate future.
Also, it's on the order of 10x the cost for similar capacity to lithium chemistries, and that comes in a package that weighs on the order of 10x as much as a similar battery.
But hey, I'm just a layman. It sounds like you probably know more.
I wonder what life is like for the new employees of elon.
I heard it will not be good.
Second, supercapacitors could also save some wear and tear on the batteries during rapid acceleration and regenerative charging.
A capacitor much smaller than the batteries acting as a buffer for rapid acceleration and braking might make sense, though.
I was under the misapprehension that they had a much larger energy density. However, my next thought is that not all charging is the same. Only the 1st 60% of a charge is in the constant current part of the charge curve. After that, the charge rate falls off. Charging the last 10% of a battery's capacity takes much longer. What if the supercapacitor bank had about 10% of the capacity of the battery? That would still be a large increase in the size and weight taken up by energy storage, though. It looks like just putting more batteries in the car is the economical thing to do.
Using a capacitor for the last 10% might make sense, or it might not. It's all about the specific numbers. It might be that a larger battery charged up to 90% might be better than a slightly smaller battery charged to 100% with the assistance of a capacitor. If you're adding a capacitor for power reasons anyways this might be a way to get more use out of it.
The use which might make sense is to use the capacitors to supplement the grid supplied power during the initial fast charge phase, then in the slower final charging phases or idle time recharge the capacitors from the grid for the next customer. This levels out the demands on the grid and can result in a lower electricity rate from the power company.
It all depends on the constants if it makes sense. Or maybe it doesn't make sense and Tesla needed something out of Maxwell's patent portfolio.
What would be an interesting use of this idea would be to have 10% capacity onboard in capacitors. Once you get within 10% of the desired charge level in the batteries, you quickly charge the capacitors, which then trickles into the battery over time.
This might allow you to increase the overall charge rate for the car which would help reduce wait times at Superchargers.
If you're not going to be using the high power of a supercapacitor, there's zero reason to pay a premium.
The idea here is to leverage their incredibly fast rate of charge and short term nature to reduce time spent Supercharging. Very roughly speaking, you can charge from 0-90% in an hour, but to go from 90-100% can take almost another hour.
If you could get the car to 90% and then very rapidly charge the capacitors with the remaining 10% that trickles in, you get the car off the charger faster. In theory you could almost double the number of cars you could serve at that station.
If supercapacitors have any role, it’s at EV charge stations to reduce demand charges from utilities. VW just agreed to buy a whole lot of Tesla batteries for this purpose at their Electrify America charge stations. Space is not an issue, as you can bury your storage under the charger stalls.
Especially here I'd expect batteries to win out as transfer capacity is roughly proportional to storage capacity with batteries.
EDIT: The above comment was meant about supercharging, not regenerative braking.
The UX would be invisible: If demand is greater than the supply available from the battery pack, drain some energy from the supercapacitors. If it's less, gradually shift some energy into them. If the driver is not in the vehicle, drain it all out, when they come back, recharge the supercaps.
The problem is that these capacitors and transfers add cost money, space, weight, energy, and complexity.
Looking at some numbers, batteries are ~20x more energy dense in both volume and weight. Batteries have 1/10th the power density, but efficiency drops significantly with discharge rate and they have fewer lifetime charge cycles and poorer temperature response. Batteries also have much, much lower self-discharge, and cost a lot less per kilowatt-hour.
Right now, lithium-ion batteries are simply good enough and supercapacitors are not that much better, so it's the cost-benefit analysis says it's better to take the costs you would have spent on supercaps and just put in a few more batteries.
That balance could shift, though, with improvements in supercap technology, or - paradoxically - with improvements in battery chemistry. If a battery with much better energy density and/or lower cost was found, with a reduced discharge rate that was sufficient to cruise but insufficient to accelerate or do regenerative braking, you could add supercaps to make a vehicle based on that battery feasible. It's similar to the electric grid - the base load would be handled by the slow batteries, similar to coal or nuclear power plants, while peaking loads would be handled by the supercapacitors, like a gas turbine.
You could preferentially store the regenerative braking energy into the ultracapacitors (and discharge from them from a stop, instead of the main battery). You're not talking a huge number of them (order of magnitude of ~100) for a cycle brake cycle at Model 3 mass, highway speed, and normal braking.
I admittedly haven't read up a ton on fast charging options but I also don't think I've seen super-capacitors mentioned as an intermediary source in any discussions. Given the article mentions Maxwell wanting to get into the automotive industry, a fast charging use is probably still a long ways out at this point.
There are some articles/rumors out there about dry electrode battery tech Maxwell was working on.
If this acquisition included any breakthrough-level battery technology, it'd be for far more than $218M as it probably would have involved a bidding war considering the stated electrification plans from all major auto manufacturers.
I don't know enough about dry battery electrode tech to know how much progress there is, how much an of an improvement they are above existing commercial technology, or who else has IP in the space.
Your response seems a bit high on the cynicism/information ratio, but I would be genuinely grateful for more information about this.
4WD off road vehicles could also have much higher torque for brief periods of time.
Capacitors can smooth out the power curve - need 1000 amps of current for 4 seconds? No problem, that comes from the capacitors and the battery only sees a draw of 200 amps. Need to regen 600 amps for 15 seconds? No problem, dump that into the capacitors and recharge the batteries at 50 amps for the next minute.
Knowing Tesla, they will use capacitors to offer both; a super-plaid mode that can supply 1800 amps momentarily, as well as better cold weather performance.
This means they have limited use in small consumer cars, other than maybe helping the brakes or conditioning power.
What they lack in weight, they make up in charge/discharge times.
Being that a truck weighs multiple times more than a sedan, it's batteries are unlikely to absorb regen braking. So a small capacitor bank makes sense. A large capacitor bank would be useful if the truck was using overhead charging cables for a small section of the road. Or if a public transport bus was quickly charging between every few stations, it could then function all day.
The large weight of the capacitor bank isn't a problem if it's used in a charging station, where 3-phase 400+ volt power may not be available. This means that any level 1,2 charger can be upgraded to a level 3 without needing to dig any trenches, further improving the user experience of the car owner and reducing range anxiety to a minimum.
It's a $50B company acquiring a small, technically related company for $200M. I don't think even TSLA bears would care.
edit: perhaps you meant https://www.sec.gov/news/press-release/2018-48 (without the 'x')? It's never good news when there's an SEC investigation, but this seems relatively minor (channel stuffing under a Sales executive, and then a < $3M settlement by the company that it should have caught it).