SuperCharging starts to feel slow

[apacheguy]

There's unlikely to be anyone posting that they wouldn't like faster charge times, but it does seem to me that there's basic math issues unless/until storage density improves:

1. Larger battery pack weighs more, therefore more energy is required to move the car.
2. Fully charging a larger battery pack will take even longer than fully charging a smaller battery pack.
3. Partially charging a larger pack (to avoid the taper) will reduce immediate range (and don't forget point #1) and potentially require more frequent stops.

A larger battery is not necessary for faster SpC. A lot can be done with improving the taper algorithm to achieve the same effect. Shifting the entire curve by 10% would have a huge effect. Most folks agree that Tesla is being very conservative with their current algorithm.

Side note: Tesla already appears to be exploring this route with the D models. Now all we need is for it to become backwards compatible with the classics.

 

[mikeash]

I know that highways speeds in the US are officially lower, but I think a lot of the US drivers would like to drive 80 mph, right?

In my experience on US interstates (mostly between Virginia and New York, and a couple of times west to Wisconsin), speeds are typically 70-75MPH. The limit is almost always 65MPH, and anything above about 75MPH is going to attract unwelcome attention from the men in blue. The unwritten rule in the US is that exceeding the limit by 10MPH or more is usually where enforcement starts to kick in. Personally I keep to about 72MPH when other conditions don't limit it further.

I don't know how much of a difference that would make to efficiency....

 

[FlasherZ]

A larger battery is not necessary for faster SpC. A lot can be done with improving the taper algorithm to achieve the same effect. Shifting the entire curve by 10% would have a huge effect. Most folks agree that Tesla is being very conservative with their current algorithm.

Side note: Tesla already appears to be exploring this route with the D models. Now all we need is for it to become backwards compatible with the classics.

I recall JB saying at some point that Tesla believed it could charge the car up to twice or even three times the rate it's currently using at Superchargers (to the effect of the current battery pack being charged halfway in 5-10 minutes), but the infrastructure becomes a bigger headache than it already is and longer-term studies need to be done before that's confirmed. However, I can't recall for the life of me where that was said, or even if I dreamed it. It has stuck with me for a while, though - generally I don't remember my dreams all that well.

Don't repeat that, unless someone else corroborates that, and treat it as hearsay unless someone else recalls the same thing.

- - - Updated - - -

In my experience on US interstates (mostly between Virginia and New York, and a couple of times west to Wisconsin), speeds are typically 70-75MPH. The limit is almost always 65MPH, and anything above about 75MPH is going to attract unwelcome attention from the men in blue. The unwritten rule in the US is that exceeding the limit by 10MPH or more is usually where enforcement starts to kick in. Personally I keep to about 72MPH when other conditions don't limit it further.

I don't know how much of a difference that would make to efficiency....

Speed limits across most rural areas are now 70 mph (or even 75). Both state troopers and county deputies have told me of the rhyme they tend to use at highway speeds: "under nine, you're fine; over nine, you're mine." That refers to MPH over limit.

 

[apacheguy]

I recall JB saying at some point that Tesla believed it could charge the car up to twice or even three times the rate it's currently using at Superchargers (to the effect of the current battery pack being charged halfway in 5-10 minutes), but the infrastructure becomes a bigger headache than it already is and longer-term studies need to be done before that's confirmed. However, I can't recall for the life of me where that was said, or even if I dreamed it. It has stuck with me for a while, though - generally I don't remember my dreams all that well.

Yeah, that was absolutely discussed. Shortly after the 120 kW announcement, someone asked "Is this the last increase we're going to see?" Answer was no.

Improving the taper though does not entail any additional infrastructure (purely software driven) so I don't see any potential for headaches.

 

[rcc]

I've done the SF to LA run and I think Cottonwood nailed it. The chargers along that route (I-5) are spaced about 110 miles apart. Spacing the superchargers 250km apart makes it possible to get from one charger to another without a completely full charge. But if you put another supercharger somewhere between so that they're between 125 to 180 km apart (75-110 miles), you can get enough charge to get to the next SC without hitting the taper to any significant degree as long you arrive at the supercharger with a reasonably low charge in your battery.

I-5 might be a reasonable approximation of European driving speeds, btw. The limit is higher (75 mph, I think) and the police don't seem to mind if you cruise at 80 mph. Probably because if you cruise at 75 mph, you almost impede traffic because everyone is going so fast.

 

[David99]

The main problem you are experiencing is the distance between the SuC. When I did my road trips I usually had 90-100 miles between them so I was able to stay mostly in the lower charge levels which is much faster. On my 2200 mile road trip I actually felt each stop was shorter than I wanted. I had planned to get some work done on those stops, but it turned out, going to the bathroom, getting a coffee checking some emails was all I could do then the car was ready again.

BUT I still think a larger battery at the same charge rate would be very useful. It would allow you to drive longer and then take a longer break which allows you to actually sit down and eat or get some work done or whatever. It would give you more room to adjust your trip and timing better and make it more convenient.

I'm pretty sure we will see an increased charge rate at SuC via software update at some point. Elon said the SuC rate is very conservative to make sure the battery lasts long. He said they don't know yet how it will affect the battery. A test with a Nissan Leaf that is fast charged all the time shows that there is very little difference in battery aging compared to one that is charged slow. That's very encouraging considering the Leaf has no battery cooling and the charge rate is more than 2C on the Leaf while it's only 1.4C on Model S and the battery is active cooled. I'm sure they will adjust the tapering curve to allow a higher rate for longer eventually.

 

[Jaff]

Just tell her that she can do some additional shopping with the money that you would have otherwise spent on gas!...works for me...:wink:

I just completed a 1100 km return trip to Ottawa and back. All of the stops were in conjunction with a meal...I found it surprising, but we could not complete a "sit down" meal and return to the car in under 50 minutes...the car was totally recharged by then...:smile:

I have had the same experience during my 2000 km round trip to Austria.
I don't mind that I have to wait but almost an hour is a bit too long. Especially my wife can't handle these "long" stops.
This eventually means we are going with an ICE car to Italy this summer.. :crying:

 

[Kipernicus]

With a 60, I'm waiting for the taper all the time. Usually we plan the trip so that supercharger stops coincide with a meal or something and it isn't an issue.

The other day, however, we needed to be up at Tahoe by 7:30pm for a dinner, and I calculated that with the kid getting out of school at 2:30, a 4 hour drive, and Friday afternoon traffic, we couldn't afford the 45-60 min wait at the SuperCharger.
Even if we had an 85 it would have been too slow.

So we took the gasser :crying:

 

[Larry Chanin]

The far simpler solution for Tesla for now is closer Supercharger spacing. My I-15/I70 experience is empirical evidence that 160-200 km (100-125 mi) spacing and good use of energy prediction is the short term solution to long Supercharger waits into the taper.

Excellent point. There are other approaches to increasing Supercharger Station overall average charging rates without the need of larger batteries.

To avoid Supercharger congestion in the future a combination of increasing the number of charging stalls at existing locations and building new Supercharger Stations closer together will be needed. Both approaches will assist in increasing Supercharger throughput via higher average charging rates. Tesla also has the option of stacking additional chargers in the Supercharger stack. This won't increase the maximum charging rates of individual cars, but it will make more capacity available and therefore increase the overall average charging rates at Supercharger Stations.

Larry

 

[widodh]

A larger battery is not necessary for faster SpC. A lot can be done with improving the taper algorithm to achieve the same effect. Shifting the entire curve by 10% would have a huge effect. Most folks agree that Tesla is being very conservative with their current algorithm.

Side note: Tesla already appears to be exploring this route with the D models. Now all we need is for it to become backwards compatible with the classics.

Fully agree, but battery safety and longevity is important as well.

I recall JB saying at some point that Tesla believed it could charge the car up to twice or even three times the rate it's currently using at Superchargers (to the effect of the current battery pack being charged halfway in 5-10 minutes), but the infrastructure becomes a bigger headache than it already is and longer-term studies need to be done before that's confirmed. However, I can't recall for the life of me where that was said, or even if I dreamed it. It has stuck with me for a while, though - generally I don't remember my dreams all that well.

Don't repeat that, unless someone else corroborates that, and treat it as hearsay unless someone else recalls the same thing.

I can believe that it's possible, but it has to be safe for the battery like mentioned above. But if the current battery technology allows it, I would be very happy.

Excellent point. There are other approaches to increasing Supercharger Station overall average charging rates without the need of larger batteries.

To avoid Supercharger congestion in the future a combination of increasing the number of charging stalls at existing locations and building new Supercharger Stations closer together will be needed. Both approaches will assist in increasing Supercharger throughput via higher average charging rates. Tesla also has the option of stacking additional chargers in the Supercharger stack. This won't increase the maximum charging rates of individual cars, but it will make more capacity available and therefore increase the overall average charging rates at Supercharger Stations.

Yes, but even more stops on your trip? I wouldn't prefer that. Going off the highway and pulling into the SuC site also takes a couple of minutes in which I would be able to travel ~7km.

Faster charging also means that people stay at the SuC shorter. So a 10% increase in SuperCharging rate also expands the SuperCharger capacity with 10%.

With Model X and Model 3 hitting the road you want the SuC sites to be utilized at their max. So faster charging also benefits Tesla!

 

[AnxietyRanger]

Most people don't often go on 1,080 km trips. However, when someone does with a Model 3, the money saved on gas will likely be an even more significant to them.

With typical speed limits, congested roads, and average stops in the USA, 1,080 km is going to take almost 11 hours in an ICE anyway. 10% longer for a rare trip is nothing when you consider the time saved charging at home and not going to the gas station on a regular basis.

I'm not so sure about "nothing".

Those 1000 km trips are often vacation trips with family and are difficult hauls in themselves. Adding 1-2 hours to 10-11 hours is not insignificant at all, especially if that means taking more than usual mandatory breaks of 1+ hours of not moving anywhere. Those chargers might also mean having to take a lounger route. There will be some very bored spouses and children sitting on the curb of some supercharger, no matter how enthusiastic about the EV experience the driver may be. Let alone if your trip takes you to non-supercharger territory...

I don't live nearby superchargers so I'm mostly dealing with an even worse situation myself and I know it takes a lot of adventurous spirit at times to drive the Model S. I have that spirit, but I also know most of my near and dear don't.

I can see it - as things currently stand - this being a showstopper in me being able to use the Model S for long family trips. That said, I also concur with NigelM in that it is what it is. Perhaps it can't be much improved at the moment on the car's end. Tesla has already done a great job (as the original poster agrees, I'm not disagreeing with him).

The solution currently is building up the infrastructure and working on the battery technology over time, as Tesla is already doing of course. Let's hope it improves sooner rather than later. But no getting around the fact that it can be a showstopping inconvenience at times, which shouldn't be belittled either.

 

[jerry33]

I'm not so sure about "nothing".

Those 1000 km trips are often vacation trips with family and are difficult hauls in themselves. Adding 1-2 hours to 10-11 hours is not insignificant at all, especially if that means taking more than usual mandatory breaks of 1+ hours of not moving anywhere.

But it's probably far safer than driving in an ICE where people tend not to stop. The only time you stop for an hour is when there is a break in the Supercharger route and you have to do a range charge. Otherwise you just stop until you have enough range plus some extra to get to the next one.

 

[Johan]

Great thread this, with lots of good suggestions and opinions.

My take on is it that time spent charging on longer trips is the only real obstacle left for EVs. This is the one variable where ICE cars are still superior. Any and everything that can be done to improve this variable is thus very important for widespread EV adoption. It's just as much about perception as it is about actual necessity.

Larger batteries and new chemistry aside, the absolutely most important thing to adress right now is taper. Some people in this thread have claimed that Tesla could create "improved algorithms" or "it's about better software". Well, I guess it would likely be literally just changing a few lines of code to make the taper occur later in the charge cycle. Software is not the reason why this is being to, IMO it's all about battery health. I know there are physical limitations that have to do with internal resistance, voltages etc. but I'm quite confident that Tesla are throtteling charging rate before these limitations occur.

Now, if we parallell this situation with the "Normal" v.s. "Range" charge, now replaced with the % slider, we couldn't Tesla have different Supercharging modes? For example "Normal" and "Agressive"? Just like if you constantly range charge to 100% the car will warn you that this accelerates battery degradation you could have the same with "Agressive" charging. It would be interesting to see how hard you could push the battery when Supercharging i.e. how far out in the charge cycle that tapering could be delayed and how much the minimum amount of tapering would be at any given SOC/Voltage.

I think Tesla do have quite some data on how battery health is affected by more agressive charging, but they're keeping the cards close to their chest on this one. My guess is that the current tapering algorithm is quite conservative. Perhaps they will gradually improve the charging, just like they did by going from 90-100-120 kW peak power?

I think the reason why they haven't done the "Normal" v.s. "Agressive" charging modes is that they don't want to put more focus than necessary on battery degradation. Even with pampering our batteries are going to degrade over time. For now, it's wise of Tesla to not put focus on this. Once this starts to become a real and noticable issue, in 4-6 years time, much will have changed: the Gigafactory will be up and running, prices will have come down, there may have been 1 or 2 step changes in battery chemistry, swapping may be more universally rolled out etc.

 

[AnxietyRanger]

But it's probably far safer than driving in an ICE where people tend not to stop. The only time you stop for an hour is when there is a break in the Supercharger route and you have to do a range charge. Otherwise you just stop until you have enough range plus some extra to get to the next one.

Not necessarily disagreeing with that in theory, but as Johan points out people's perception does play a part as well. If people expect to be moving faster and with less stops with an ICE, and the trip is already pushing the envelope endurance-wise, this will affect them regardless of how much better the EV trip otherwise might be. There is risk and "social cost" associated with travelling 1000+ km with company in any method. If the people travelling with you aren't happy, you won't be either and unhappy people can make for a bad day - and bad days tend to distract in all sorts of ways.

Obviously if EVs win the day (on other, very real, merits) and waiting to charge becomes the new normal, then this issue will go away to an extent. It is partially about expectation management for sure.

 

[widodh]

Great thread this, with lots of good suggestions and opinions.

My take on is it that time spent charging on longer trips is the only real obstacle left for EVs. This is the one variable where ICE cars are still superior. Any and everything that can be done to improve this variable is thus very important for widespread EV adoption. It's just as much about perception as it is about actual necessity.

Larger batteries and new chemistry aside, the absolutely most important thing to adress right now is taper. Some people in this thread have claimed that Tesla could create "improved algorithms" or "it's about better software". Well, I guess it would likely be literally just changing a few lines of code to make the taper occur later in the charge cycle. Software is not the reason why this is being to, IMO it's all about battery health. I know there are physical limitations that have to do with internal resistance, voltages etc. but I'm quite confident that Tesla are throtteling charging rate before these limitations occur.

Now, if we parallell this situation with the "Normal" v.s. "Range" charge, now replaced with the % slider, we couldn't Tesla have different Supercharging modes? For example "Normal" and "Agressive"? Just like if you constantly range charge to 100% the car will warn you that this accelerates battery degradation you could have the same with "Agressive" charging. It would be interesting to see how hard you could push the battery when Supercharging i.e. how far out in the charge cycle that tapering could be delayed and how much the minimum amount of tapering would be at any given SOC/Voltage.

I think Tesla do have quite some data on how battery health is affected by more agressive charging, but they're keeping the cards close to their chest on this one. My guess is that the current tapering algorithm is quite conservative. Perhaps they will gradually improve the charging, just like they did by going from 90-100-120 kW peak power?

I think the reason why they haven't done the "Normal" v.s. "Agressive" charging modes is that they don't want to put more focus than necessary on battery degradation. Even with pampering our batteries are going to degrade over time. For now, it's wise of Tesla to not put focus on this. Once this starts to become a real and noticable issue, in 4-6 years time, much will have changed: the Gigafactory will be up and running, prices will have come down, there may have been 1 or 2 step changes in battery chemistry, swapping may be more universally rolled out etc.

Great thinking and reasoning. Charging settings would be nice indeed. Faster charging is indeed the only thing which I want in my Model S.

Not necessarily disagreeing with that in theory, but as Johan points out people's perception does play a part as well. If people expect to be moving faster and with less stops with an ICE, and the trip is already pushing the envelope endurance-wise, this will affect them regardless of how much better the EV trip otherwise might be. There is risk and "social cost" associated with travelling 1000+ km with company in any method. If the people travelling with you aren't happy, you won't be either and unhappy people can make for a bad day - and bad days tend to distract in all sorts of ways.

I did my last trip with 4 adults. We could have swapped driver at each charge, so no need for any resting, we could simply continue.

 

[LuckyLuke]

I quite like that idea of a optional "agressive mode" for supercharging !

 

[brucet999]

State of the art grapheme capacitors get to about 20%.

Is that a device to electronically store letters and numerals (ie: graphemes)?

In fairness, I should note that you meant to type "graphene" and "N" is next to "M" on the keyboard.

Cheers

 

[apacheguy]

I quite like that idea of a optional "agressive mode" for supercharging !

Not sure they even need that. If the pushed back the 90 kW taper threshold to 50% I doubt that long term degradation data would show a significant difference. This would satisfy most owners' complaints about slow charging.

 

[Johan]

Not sure they even need that. If the pushed back the 90 kW taper threshold to 50% I doubt that long term degradation data would show a significant difference. This would satisfy most owners' complaints about slow charging.

Well, this would be "aggressive mode" then

 

[FairFrank]

+1

If Tesla marketeers advertise Superchargers with '80% in 40 mins', it doesn't feel good when charging 200 km/hour.
Maybe they can introduce aside Superchargers (that truly deliver 120kW) a new class of 'Eurochargers' (95kw) and 'Dieselchargers' (70kW).
A deja vu in the future?