14 ms·

Tesla’s promises don’t compute with current physics and economics of batteries

110 points by watchdogtimer 9y ago

joshuamcneese 9y ago
The “laws of batteries”?
- mirimir 9y ago
  That seems to mean current battery performance.
- melling 9y ago
  “Every time the global supply of batteries doubled, prices drop 19%” “Every year the energy density of batteries increases by about 7.5%” So, in 10 years electric cars will double their range, which should be more than enough for most people.
  - Hypx 9y ago
    We should be careful with apply Moore's Law style of thinking when it comes to battery innovation. These things can and will hit hard limits at some point. Real progress can be much slower and much less predictable than in the semiconductor industry.
    - jsight 9y ago
      The funny thing is that it really hasn't been that much less predictable. Progress has been slow but steady and Tesla's business model has been built around largely predictable technological progress. 7.5%/year is probably an overestimate, though, and you are right that at some point it will hit diminishing returns. Moore's law has too, though, eh?
mirimir 9y ago
It's an informative article, but the title is inaccurate. Tesla seems to be relying on plausible extrapolations for batteries in ~2020.
- mtgx 9y ago
  Bingo. Not only that, but they may even rely on battery extrapolations for 2022, despite the truck and car being launched in 2019-2020. All they need is to break-even in the first year or two, and then they can make-up the profits from the improvement in battery prices. That said, the roadster itself will likely be profitable from day one. It's the truck that may not be. This is why Musk keeps getting ahead of everyone else and leaves carmakers and media writers in "shock and awe" - because he keeps thinking outside of the box, while they keep thinking within the existing or past constraints.
  - flor1s 9y ago
    Meh, I think other companies just don't have the bravoure a man like Musk has. Also it helps if your company is a start-up and no heads will roll if you don't make a profit. Established companies don't have that luxury.
    - toomuchtodo 9y ago
      Established companies keep their stock price high by being conservative. Startups/growth companies keep their stock price high by pushing the envelope.
    - erikpukinskis 9y ago
      You don’t need bravoure to do math.
- kalleboo 9y ago
  And if there's anyone who has good estimations to extrapolate the price and density development of batteries, it's the company that's building the world's biggest battery factory in close collaboration with one of the world's foremost battery manufacturers.
itchyjunk 9y ago
Although it is very good to be skeptical, it makes the article less valuable than it could have been. 'Musk claimed X and people we talked to said they don't know how it's possible.' I am not saying that the people they consulted didn't know how, but using just that for the entire article was unnecessary. They also claim battery density is increasing by Y% and maybe Tesla is banking on that. Well those density increases because someone somewhere is finding ways to do it. It's not happening by some magic. Maybe Tesla found some ways to improve it? Why do they have to rely on someone else? Maybe I am being too critical of the article and I understand that author too can do very little but speculate. But maybe consult variety of people rather than just 'I don't know how so it must not be possible' people. Edit: is there a way for tesla to purchase electricity for solar city customers or something and direct it to charging stations? Or is that now how it all works?
- shobith 9y ago
  They could have easily added a few more people speaking while they were at it: https://asia.nikkei.com/Tech-Science/Tech/New-battery-technologies-still-years-away?page=2 https://asia.nikkei.com/Tech-Science/Tech/New-battery-techno...
  - itchyjunk 9y ago
    Very good supplement information. I didn't realize Li ion batteries were so close to their theoretical limit.
- jsight 9y ago
  While I see some crazy talk in that article, I'm actually pleased with the idea of getting the point across that this requires technical advances. So many people just nonchalantaly act like they just tossed a few more 18650s in there that it is nice to see someone point out how improbable that is. I'm really looking forward to hearing how this is actually happening.
mcguire 9y ago
"Tesla offers free electricity to most of its Model S and Model X customers while paying almost $1 per kilowatt hour to produce it, Morsy said. That amounts to a subsidy of as much as $1,000 per car in 2017." I realize that most people believe that Tesla and Uber will be able to continue subsidising their operations indefinitely, but it makes me very nervous.
- jsight 9y ago
  I can't take this author seriously. There is no way that Tesla is paying $1/kw. That is way past the retail rate, and I bet that they are paying much less than the retail rate in many of their markets.
  - vvanders 9y ago
    Yeah, that's definitely bullshit, esp considering residential power in the PNW is $0.07/kWh.
    - DannyBee 9y ago
      Residential power is often cheaper than commercial (at least, small scale) in practice. One reason is that commercial folks pay surcharges for power factor. For example, in San Jose, CA, the average residential is ~$0.156/kwh Commercial is $0.1408/kwh [1]. If you operate at a 90% power factor, and are surcharged the other 10%, ... [1] https://www.electricitylocal.com/states/california/san-jose/ https://www.electricitylocal.com/states/california/san-jose/ But yeah, at Tesla's scale, it should not be $1/kw. I could believe that to be the all-in cost for a supercharger or something weird like that. Because they should be paying close to the industrial rate, if not lower.
      - jimrandomh 9y ago
        Nope. Electricity for residential use costs more than electricity for commercial use, which costs more than electricity for industrial use. A fast-charging truck stop is most similar to industrial use, since it involves a lot of power at a single location, and probably also can give the utility at least a few minutes warning before ramping up to full power. From the Energy Information Administration: https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
ams6110 9y ago
If this were any other company making such unsubstantiated claims that didn't have any basis in the reality of the underlying technology, they'd be getting roasted here.
- jsight 9y ago
  I don't really agree. If another company rolled a 200kwh car out of the back of a truck, did a few passes of the stage, gave passengers rides (high speed launches) for a while, and then reported ~60% battery remaining, I think most would believe them. We would also wonder about making it to production, but Tesla actually has a halfway decent track record at that.
  - lukealization 9y ago
    > If another company rolled a 200kwh car out of the back of a truck ... That's the thing. They didn't. The roadster concept didn't have 200kWh in it at all.
    - _ph_ 9y ago
      It might not have exactly 200kWh of battery installed, but one reason for planning such a large battery is to be able to support the neccessary current levels for the accelleration they have demonstrated. So they couldn't have just put a small battery in the car either.
    - jsight 9y ago
      At the show, they were saying that it did. Do you have some evidence to the contrary?
- ktta 9y ago
  Well, the article makes it sounds like they are defying physics - "breaks laws of batteries"? Then also quotes >“I don't think they're lying,” Jaffe said. “I just think they left something out of the public reveal that would have explained how these numbers work.” There are no laws here, just advances in battery tech, and people believe Tesla is at the forefront of that AFAIK. Sure, they might be making claims that are hard to believe, but isn't the point of Tesla doing exactly that?
watchdogtimer 9y ago
> To meet Tesla’s claim of 400 miles in 30 minutes for a semi carrying 80,000 pounds would require its new Megachargers to achieve output of more than 1200 kW 1200 kw is a lot of power. That's the average amount of power used by 600 homes, or half of the output of a large wind turbine here in the Midwest, to charge a single truck. If they use a 440 V supply to charge it, that'd be over 2700 amps.
- vvanders 9y ago
  Eh, there's 20 120kW stalls in the Centralia Supercharger so while it's a lot I don't think it's crazy-talk.
- Animats 9y ago
  That requires a really big plug. Like this one, 400 amps at 440VAC, three phase.[1] There's a standard plug for plugging large ships into shore power. Truck stops are going to need high tension lines coming in. [1] http://www.cooperindustries.com/content/public/en/wiring_devices/interconnect/products/subsea/shore_power_cables_mil_c_24368.html http://www.cooperindustries.com/content/public/en/wiring_dev...
  - ChuckMcM 9y ago
    I wonder if they might do some sort of powerwall setup where they install a battery bank at the truck stop that can supply the power, it gets charged off the grid constantly, periodically trucks come in and suck big chunks of power out of it.
- foota 9y ago
  Sounds like their existing chargers are already 480V. [https://en.wikipedia.org/wiki/Tesla_Supercharger https://en.wikipedia.org/wiki/Tesla_Supercharger]
- dboreham 9y ago
  I might have been skeptical too but I recently saw a _ship_ charged while docked for about 50min in Norway. Big plugs, two circuits and I think 600V. I took a picture that I could dig out for the curious.
techbubble 9y ago
What would prevent the battery from having a segmented design so that multiple segments can be charged in parallel? Is there something about the chemistry that requires the entire vehicle battery to be a single unit?
- TylerE 9y ago
  At some point the size of the connector TO the vehicle is going to be the limiting factor.
  - techbubble 9y ago
    I was thinking of batteries connected in series with a mechanism to separate the connection during charging. The main connector would be the same. Perhaps this is just not possible with huge batteries? Edit: Oh I get it...the charging port is what you meant.
    - kumarvvr 9y ago
      Exactly my thought. Relays that connect the batteries in series for charging and reconnect in parallel for driving.
  - andreyf 9y ago
    In the case of a truck, that seems less likely -- surely they could come up with a design that hooks in 2, 3, 10 plugs the moment the truck is ready to dock.
    - simonsarris 9y ago
      Their design has 4/8 ports: https://insideevs.com/wp-content/uploads/2017/12/Tesla-Semi-Charging-Port-2.jpg https://insideevs.com/wp-content/uploads/2017/12/Tesla-Semi-...
      - andreyf 9y ago
        Nice! I guess the width of the wires is the limiting factor? Or a cooling system? Regardless, curious to hear an informed analysis.
nimos 9y ago
The Tesla superchargers currently charge at around 2% a minute up until about 80% which is 40 minutes to hit 80%. Tesla is advertising 400 miles in 30 minutes which is 80% of the 500 mile capacity. What is so hard to believe about a 33% improvement over a couple year old tech that is a couple years from release? Here are current industrial/transportation/residential electric prices in US [0]. They think Tesla will pay 40c a kwh??? What a joke. Sure if you look at constant demand facilities and extrapolate their pricing model with low average demand to megachargers you can come up with a ridiculous number. You can literally run diesel generators and generate electricity for a lower cost. This is so hysterically asinine I can't believe Bloomberg published this article. Not to mention a huge amount of charging can happen overnight when drivers are sleeping and electricity prices/demand are super low. Pushing a lot of power through a wire is a solved problem. So what they need to push 10x through one connection instead of over 10. We are talking about a modest increase in % charge rates. That is what matters. All else equal you can charge a percent of your battery capacity not some arbitrary fixed number. This is an embarrassingly poor article. I think the one the worst things about the current tech shortage is now we have all these arts/business majors doing technology writing larping like they know the difference between a watt and an amp. [0]https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
- jepler 9y ago
  Look at charging rates in watts (watt hours per hour) instead of in percentage; those semis have much larger capacity batteries, so they need a higher charging rate in W to charge 80% in 30 minutes than a vehicle with a smaller battery.
  - cperciva 9y ago
    They don't have larger capacity batteries. They have batteries with more cells. Sure, the total charging rate is a higher Wattage, but you can charge cells in parallel. The scaling here is exactly the same as with the "larger battery" versions of the Model S having more horsepower; higher capacity = higher throughput when you're dealing with battery banks.
pfarnsworth 9y ago
Can't you just have multiple super-chargers charging different banks of batteries in parallel?
- fencepost 9y ago
  Not sure why this is getting downvotes, it seems like a blindingly obvious part of the system. As for power to the chargers and paying high premiums for surge loads, it's a real shame there's no technology that Tesla could use to accumulate and store power locally at stations with local storage capacity determined based on expected usage. For that matter, just take the flat frame/battery pack of the current cars and make them replaceable slabs on rails. Charge each one independently or swap them out, though that'd probably be a service thing instead since you probably want to keep those trucks on the road as much as possible.
- CodeWriter23 9y ago
  Yes, but only if you understand how electricity works. And indeed, rapid parallel recharging is required for the regenerative braking system whilst burning up the Autobahn in Ludicrous Mode. The motors can throw up to 1600 amps while braking and the batteries can soak it all up...until thermal limits are hit and then the mechanical brakes have to kick in. Apparently the Bloomberg “expert” doesn’t grasp basic electric principles like wiring in parallel.
marklyon 9y ago
The correct term is “disrupt”.
excalibur 9y ago
I think most people are in agreement that the lithium ion battery is less-than-ideal technology that's due for replacement. And we have a number of innovations in battery technology vying for the opportunity. It's starting to feel a bit like Tesla's massive investments are only serving to further entrench the existing battery model. He's basically working to replace Big Oil with Big Lithium. There's no denying the benefits of breaking our addiction to fossil fuels, but we need to be mindful of the obstacles to tomorrow's progress we're erecting in the name of today's.
- maratd 9y ago
  > And we have a number of innovations in battery technology vying for the opportunity. No, we don't. We have lots of news articles about amazing breakthroughs and absolutely nothing in actual production. > It's starting to feel a bit like Tesla's massive investments are only serving to further entrench the existing battery model. If you can come up with a battery chemistry that outperforms lithium ion, there will be nothing stopping the absolutely massive torrential downpour of money on top of you. Batteries are used everywhere, not just in cars. A new chemistry that works well would be huge. The problem is that there's lots of hype and marginal results when it comes to new battery tech.
- dreamcompiler 9y ago
  > He's basically working to replace Big Oil with Big Lithium. Electric cars need X kg of elemental lithium over the lifetime of the car. ICE cars need [on the order of] X kg of gasoline every 200 miles. This makes such a huge quantitative difference that comparing lithium mining to oil mining is almost pointless. In addition, lithium can in principle be recycled when the battery wears out. Gasoline cannot be recycled, even in principle.
  - nbanks 9y ago
    Some CO2 hydrogenation processes can produce liquid fuels which is kind of like recycling gasoline, but this is much more complicated than recycling batteries. It may still prove useful for fueling rockets or aircraft in a CO2 neutral way.
MentallyRetired 9y ago
> based on Bloomberg's estimates Oh, good. I thought they were going to bring in a battery expert to disprove the battery experts that work for the company who, according to Bloomberg, has the most advanced charging systems on the market. Whew! Dodged a bullet, there.
deleted 9y ago
[deleted]
seriouslypy 9y ago
Ok, who payed Bloomberg?
xg15 9y ago
> Musk’s claim that the truck will be able to accumulate 400 miles of charge in 30 minutes would allow the Semi to achieve the first true long-haul ranges in the industry. A driver might start the day with 500 miles of range, top off the battery at lunch, and be able to complete driving the U.S. legal limit of 11 hours in a day with range to spare. But doing so would require a charger unlike anything seen before. Stupid question: Why is it no option to simply hot-swap the battery? (Possibly with mechanical assistance) If you're already talking about a scenario where the charging happens at motels or gas stations, it seems easiest to have a stock of batteries that you can charge over longer time and swap them out whever a truck comes in.
- lovemenot 9y ago
  This is more of an economic / business problem than a technical one. Just who do you think would be the owner of the replacement battery packs? If your answer is Tesla, then you've made huge and IMHO unrealistic assumptions about Tesla's capital allocations. If you expect haulage companies to buy and charge batteries around their most likely needed locations then you are even further off. In nearly every case, their business demands extreme routing flexibility.
- bpicolo 9y ago
  Estimates for the weight of the battery put it at like 10,000-20,000 pounds, and it's a 120,000 dollar battery. Who's going to maintain a million-dollar battery stock? You'd need liability insurance and equipment out the ass to deal with batteries that large. That's not a procedure you'd easily get done in 30 minutes. Charging the dang thing is a way better model.
ChuckMcM 9y ago
Given Tesla's recent experience in building the South Australian battery bank, I wonder if it is possible to build something similar at a truck stop. Imagine a 10MWh battery pack that constantly charges from the grid, when a truck pulls in it can dump charge into the truck at a high rate. I was thinking about diesel which is trucked in to the truckstop and stored in tanks, and then pumped out when needed. This would store charge in batteries and then pump it out when needed.
johngrefe 9y ago
It breaks the "laws of batteries" until it doesn't. Has everyone lost their memory retention? Maybe everyone on HN is Software centric and hardware hobbyist. Fair enough. Big things coming in the battery space. https://news.utexas.edu/2017/02/28/goodenough-introduces-new-battery-technology https://news.utexas.edu/2017/02/28/goodenough-introduces-new...
mgiannopoulos 9y ago
Bloomberg trying to manipulate the stock price? Could it be?

110 points by watchdogtimer 9y ago

joshuamcneese 9y ago

The “laws of batteries”?

mirimir 9y ago
That seems to mean current battery performance.
melling 9y ago
“Every time the global supply of batteries doubled, prices drop 19%” “Every year the energy density of batteries increases by about 7.5%” So, in 10 years electric cars will double their range, which should be more than enough for most people.
- Hypx 9y ago
  We should be careful with apply Moore's Law style of thinking when it comes to battery innovation. These things can and will hit hard limits at some point. Real progress can be much slower and much less predictable than in the semiconductor industry.
  - jsight 9y ago
    The funny thing is that it really hasn't been that much less predictable. Progress has been slow but steady and Tesla's business model has been built around largely predictable technological progress. 7.5%/year is probably an overestimate, though, and you are right that at some point it will hit diminishing returns. Moore's law has too, though, eh?

mirimir 9y ago

It's an informative article, but the title is inaccurate. Tesla seems to be relying on plausible extrapolations for batteries in ~2020.

mtgx 9y ago
Bingo. Not only that, but they may even rely on battery extrapolations for 2022, despite the truck and car being launched in 2019-2020. All they need is to break-even in the first year or two, and then they can make-up the profits from the improvement in battery prices. That said, the roadster itself will likely be profitable from day one. It's the truck that may not be. This is why Musk keeps getting ahead of everyone else and leaves carmakers and media writers in "shock and awe" - because he keeps thinking outside of the box, while they keep thinking within the existing or past constraints.
- flor1s 9y ago
  Meh, I think other companies just don't have the bravoure a man like Musk has. Also it helps if your company is a start-up and no heads will roll if you don't make a profit. Established companies don't have that luxury.
  - toomuchtodo 9y ago
    Established companies keep their stock price high by being conservative. Startups/growth companies keep their stock price high by pushing the envelope.
  - erikpukinskis 9y ago
    You don’t need bravoure to do math.
kalleboo 9y ago
And if there's anyone who has good estimations to extrapolate the price and density development of batteries, it's the company that's building the world's biggest battery factory in close collaboration with one of the world's foremost battery manufacturers.

itchyjunk 9y ago

Although it is very good to be skeptical, it makes the article less valuable than it could have been. 'Musk claimed X and people we talked to said they don't know how it's possible.' I am not saying that the people they consulted didn't know how, but using just that for the entire article was unnecessary. They also claim battery density is increasing by Y% and maybe Tesla is banking on that. Well those density increases because someone somewhere is finding ways to do it. It's not happening by some magic. Maybe Tesla found some ways to improve it? Why do they have to rely on someone else? Maybe I am being too critical of the article and I understand that author too can do very little but speculate. But maybe consult variety of people rather than just 'I don't know how so it must not be possible' people. Edit: is there a way for tesla to purchase electricity for solar city customers or something and direct it to charging stations? Or is that now how it all works?

shobith 9y ago
They could have easily added a few more people speaking while they were at it: https://asia.nikkei.com/Tech-Science/Tech/New-battery-technologies-still-years-away?page=2 https://asia.nikkei.com/Tech-Science/Tech/New-battery-techno...
- itchyjunk 9y ago
  Very good supplement information. I didn't realize Li ion batteries were so close to their theoretical limit.
jsight 9y ago
While I see some crazy talk in that article, I'm actually pleased with the idea of getting the point across that this requires technical advances. So many people just nonchalantaly act like they just tossed a few more 18650s in there that it is nice to see someone point out how improbable that is. I'm really looking forward to hearing how this is actually happening.

mcguire 9y ago

"Tesla offers free electricity to most of its Model S and Model X customers while paying almost $1 per kilowatt hour to produce it, Morsy said. That amounts to a subsidy of as much as $1,000 per car in 2017." I realize that most people believe that Tesla and Uber will be able to continue subsidising their operations indefinitely, but it makes me very nervous.

jsight 9y ago
I can't take this author seriously. There is no way that Tesla is paying $1/kw. That is way past the retail rate, and I bet that they are paying much less than the retail rate in many of their markets.
- vvanders 9y ago
  Yeah, that's definitely bullshit, esp considering residential power in the PNW is $0.07/kWh.
  - DannyBee 9y ago
    Residential power is often cheaper than commercial (at least, small scale) in practice. One reason is that commercial folks pay surcharges for power factor. For example, in San Jose, CA, the average residential is ~$0.156/kwh Commercial is $0.1408/kwh [1]. If you operate at a 90% power factor, and are surcharged the other 10%, ... [1] https://www.electricitylocal.com/states/california/san-jose/ https://www.electricitylocal.com/states/california/san-jose/ But yeah, at Tesla's scale, it should not be $1/kw. I could believe that to be the all-in cost for a supercharger or something weird like that. Because they should be paying close to the industrial rate, if not lower.
    - jimrandomh 9y ago
      Nope. Electricity for residential use costs more than electricity for commercial use, which costs more than electricity for industrial use. A fast-charging truck stop is most similar to industrial use, since it involves a lot of power at a single location, and probably also can give the utility at least a few minutes warning before ramping up to full power. From the Energy Information Administration: https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...

ams6110 9y ago

If this were any other company making such unsubstantiated claims that didn't have any basis in the reality of the underlying technology, they'd be getting roasted here.

jsight 9y ago
I don't really agree. If another company rolled a 200kwh car out of the back of a truck, did a few passes of the stage, gave passengers rides (high speed launches) for a while, and then reported ~60% battery remaining, I think most would believe them. We would also wonder about making it to production, but Tesla actually has a halfway decent track record at that.
- lukealization 9y ago
  > If another company rolled a 200kwh car out of the back of a truck ... That's the thing. They didn't. The roadster concept didn't have 200kWh in it at all.
  - _ph_ 9y ago
    It might not have exactly 200kWh of battery installed, but one reason for planning such a large battery is to be able to support the neccessary current levels for the accelleration they have demonstrated. So they couldn't have just put a small battery in the car either.
  - jsight 9y ago
    At the show, they were saying that it did. Do you have some evidence to the contrary?
ktta 9y ago
Well, the article makes it sounds like they are defying physics - "breaks laws of batteries"? Then also quotes >“I don't think they're lying,” Jaffe said. “I just think they left something out of the public reveal that would have explained how these numbers work.” There are no laws here, just advances in battery tech, and people believe Tesla is at the forefront of that AFAIK. Sure, they might be making claims that are hard to believe, but isn't the point of Tesla doing exactly that?

watchdogtimer 9y ago

> To meet Tesla’s claim of 400 miles in 30 minutes for a semi carrying 80,000 pounds would require its new Megachargers to achieve output of more than 1200 kW 1200 kw is a lot of power. That's the average amount of power used by 600 homes, or half of the output of a large wind turbine here in the Midwest, to charge a single truck. If they use a 440 V supply to charge it, that'd be over 2700 amps.

vvanders 9y ago
Eh, there's 20 120kW stalls in the Centralia Supercharger so while it's a lot I don't think it's crazy-talk.
Animats 9y ago
That requires a really big plug. Like this one, 400 amps at 440VAC, three phase.[1] There's a standard plug for plugging large ships into shore power. Truck stops are going to need high tension lines coming in. [1] http://www.cooperindustries.com/content/public/en/wiring_devices/interconnect/products/subsea/shore_power_cables_mil_c_24368.html http://www.cooperindustries.com/content/public/en/wiring_dev...
- ChuckMcM 9y ago
  I wonder if they might do some sort of powerwall setup where they install a battery bank at the truck stop that can supply the power, it gets charged off the grid constantly, periodically trucks come in and suck big chunks of power out of it.
foota 9y ago
Sounds like their existing chargers are already 480V. [https://en.wikipedia.org/wiki/Tesla_Supercharger https://en.wikipedia.org/wiki/Tesla_Supercharger]
dboreham 9y ago
I might have been skeptical too but I recently saw a _ship_ charged while docked for about 50min in Norway. Big plugs, two circuits and I think 600V. I took a picture that I could dig out for the curious.

techbubble 9y ago

What would prevent the battery from having a segmented design so that multiple segments can be charged in parallel? Is there something about the chemistry that requires the entire vehicle battery to be a single unit?

TylerE 9y ago
At some point the size of the connector TO the vehicle is going to be the limiting factor.
- techbubble 9y ago
  I was thinking of batteries connected in series with a mechanism to separate the connection during charging. The main connector would be the same. Perhaps this is just not possible with huge batteries? Edit: Oh I get it...the charging port is what you meant.
  - kumarvvr 9y ago
    Exactly my thought. Relays that connect the batteries in series for charging and reconnect in parallel for driving.
- andreyf 9y ago
  In the case of a truck, that seems less likely -- surely they could come up with a design that hooks in 2, 3, 10 plugs the moment the truck is ready to dock.
  - simonsarris 9y ago
    Their design has 4/8 ports: https://insideevs.com/wp-content/uploads/2017/12/Tesla-Semi-Charging-Port-2.jpg https://insideevs.com/wp-content/uploads/2017/12/Tesla-Semi-...
    - andreyf 9y ago
      Nice! I guess the width of the wires is the limiting factor? Or a cooling system? Regardless, curious to hear an informed analysis.

nimos 9y ago

The Tesla superchargers currently charge at around 2% a minute up until about 80% which is 40 minutes to hit 80%. Tesla is advertising 400 miles in 30 minutes which is 80% of the 500 mile capacity. What is so hard to believe about a 33% improvement over a couple year old tech that is a couple years from release? Here are current industrial/transportation/residential electric prices in US [0]. They think Tesla will pay 40c a kwh??? What a joke. Sure if you look at constant demand facilities and extrapolate their pricing model with low average demand to megachargers you can come up with a ridiculous number. You can literally run diesel generators and generate electricity for a lower cost. This is so hysterically asinine I can't believe Bloomberg published this article. Not to mention a huge amount of charging can happen overnight when drivers are sleeping and electricity prices/demand are super low. Pushing a lot of power through a wire is a solved problem. So what they need to push 10x through one connection instead of over 10. We are talking about a modest increase in % charge rates. That is what matters. All else equal you can charge a percent of your battery capacity not some arbitrary fixed number. This is an embarrassingly poor article. I think the one the worst things about the current tech shortage is now we have all these arts/business majors doing technology writing larping like they know the difference between a watt and an amp. [0]https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...

jepler 9y ago
Look at charging rates in watts (watt hours per hour) instead of in percentage; those semis have much larger capacity batteries, so they need a higher charging rate in W to charge 80% in 30 minutes than a vehicle with a smaller battery.
- cperciva 9y ago
  They don't have larger capacity batteries. They have batteries with more cells. Sure, the total charging rate is a higher Wattage, but you can charge cells in parallel. The scaling here is exactly the same as with the "larger battery" versions of the Model S having more horsepower; higher capacity = higher throughput when you're dealing with battery banks.

pfarnsworth 9y ago

Can't you just have multiple super-chargers charging different banks of batteries in parallel?

fencepost 9y ago
Not sure why this is getting downvotes, it seems like a blindingly obvious part of the system. As for power to the chargers and paying high premiums for surge loads, it's a real shame there's no technology that Tesla could use to accumulate and store power locally at stations with local storage capacity determined based on expected usage. For that matter, just take the flat frame/battery pack of the current cars and make them replaceable slabs on rails. Charge each one independently or swap them out, though that'd probably be a service thing instead since you probably want to keep those trucks on the road as much as possible.
CodeWriter23 9y ago
Yes, but only if you understand how electricity works. And indeed, rapid parallel recharging is required for the regenerative braking system whilst burning up the Autobahn in Ludicrous Mode. The motors can throw up to 1600 amps while braking and the batteries can soak it all up...until thermal limits are hit and then the mechanical brakes have to kick in. Apparently the Bloomberg “expert” doesn’t grasp basic electric principles like wiring in parallel.

marklyon 9y ago

The correct term is “disrupt”.

excalibur 9y ago

I think most people are in agreement that the lithium ion battery is less-than-ideal technology that's due for replacement. And we have a number of innovations in battery technology vying for the opportunity. It's starting to feel a bit like Tesla's massive investments are only serving to further entrench the existing battery model. He's basically working to replace Big Oil with Big Lithium. There's no denying the benefits of breaking our addiction to fossil fuels, but we need to be mindful of the obstacles to tomorrow's progress we're erecting in the name of today's.

maratd 9y ago
> And we have a number of innovations in battery technology vying for the opportunity. No, we don't. We have lots of news articles about amazing breakthroughs and absolutely nothing in actual production. > It's starting to feel a bit like Tesla's massive investments are only serving to further entrench the existing battery model. If you can come up with a battery chemistry that outperforms lithium ion, there will be nothing stopping the absolutely massive torrential downpour of money on top of you. Batteries are used everywhere, not just in cars. A new chemistry that works well would be huge. The problem is that there's lots of hype and marginal results when it comes to new battery tech.
dreamcompiler 9y ago
> He's basically working to replace Big Oil with Big Lithium. Electric cars need X kg of elemental lithium over the lifetime of the car. ICE cars need [on the order of] X kg of gasoline every 200 miles. This makes such a huge quantitative difference that comparing lithium mining to oil mining is almost pointless. In addition, lithium can in principle be recycled when the battery wears out. Gasoline cannot be recycled, even in principle.
- nbanks 9y ago
  Some CO2 hydrogenation processes can produce liquid fuels which is kind of like recycling gasoline, but this is much more complicated than recycling batteries. It may still prove useful for fueling rockets or aircraft in a CO2 neutral way.

MentallyRetired 9y ago

> based on Bloomberg's estimates Oh, good. I thought they were going to bring in a battery expert to disprove the battery experts that work for the company who, according to Bloomberg, has the most advanced charging systems on the market. Whew! Dodged a bullet, there.

deleted 9y ago

[deleted]

seriouslypy 9y ago

Ok, who payed Bloomberg?

xg15 9y ago

> Musk’s claim that the truck will be able to accumulate 400 miles of charge in 30 minutes would allow the Semi to achieve the first true long-haul ranges in the industry. A driver might start the day with 500 miles of range, top off the battery at lunch, and be able to complete driving the U.S. legal limit of 11 hours in a day with range to spare. But doing so would require a charger unlike anything seen before. Stupid question: Why is it no option to simply hot-swap the battery? (Possibly with mechanical assistance) If you're already talking about a scenario where the charging happens at motels or gas stations, it seems easiest to have a stock of batteries that you can charge over longer time and swap them out whever a truck comes in.

lovemenot 9y ago
This is more of an economic / business problem than a technical one. Just who do you think would be the owner of the replacement battery packs? If your answer is Tesla, then you've made huge and IMHO unrealistic assumptions about Tesla's capital allocations. If you expect haulage companies to buy and charge batteries around their most likely needed locations then you are even further off. In nearly every case, their business demands extreme routing flexibility.
bpicolo 9y ago
Estimates for the weight of the battery put it at like 10,000-20,000 pounds, and it's a 120,000 dollar battery. Who's going to maintain a million-dollar battery stock? You'd need liability insurance and equipment out the ass to deal with batteries that large. That's not a procedure you'd easily get done in 30 minutes. Charging the dang thing is a way better model.

ChuckMcM 9y ago

Given Tesla's recent experience in building the South Australian battery bank, I wonder if it is possible to build something similar at a truck stop. Imagine a 10MWh battery pack that constantly charges from the grid, when a truck pulls in it can dump charge into the truck at a high rate. I was thinking about diesel which is trucked in to the truckstop and stored in tanks, and then pumped out when needed. This would store charge in batteries and then pump it out when needed.

johngrefe 9y ago

It breaks the "laws of batteries" until it doesn't. Has everyone lost their memory retention? Maybe everyone on HN is Software centric and hardware hobbyist. Fair enough. Big things coming in the battery space. https://news.utexas.edu/2017/02/28/goodenough-introduces-new-battery-technology https://news.utexas.edu/2017/02/28/goodenough-introduces-new...

mgiannopoulos 9y ago

Bloomberg trying to manipulate the stock price? Could it be?