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

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

#121

Post by bogomipz »

nimos wrote: post #30

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 pa…

>"The Tesla superchargers currently charge at around 2% a minute up until about 80% which is 40 minutes to hit 80%."

I am curious what exactly happens at 80%, does that 2% a minute rate drop off precipitously? If so what is the reason for that?

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

#122

Post by jimrandomh »

DannyBee wrote: post #60
vvanders wrote: post #21

Earlier quoted context omitted.

Yeah, that's definitely bullshit, esp considering residential power in the PNW is $0.07/kWh.

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/ But yeah, at Tesla's s…

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.ph...

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

#123

Post by syshum »

firebones wrote: post #70
extrapickles wrote: post #38

Earlier quoted context omitted.

Truckers are even required to take a federally mandated 30 minute break[0] during the day, during which the truck can be recharging. Industrial applications already consume much more power than an entire Megacharger site, so supplying the charger with power is an already solved problem. Getting power from the charger the truck is again, a solved problem in the industrial space. I can order an off the shelf industrial…

The regulatory info only gives information on the way things should be with regard to how truckers and the interstate highway system works, but I would suggest that before you invest on this hypothesis, talk to some truckers earning $0.50 per mile. And look at where semis actually park when they're taking their 30 minute and 11 hour breaks, before deciding how fast this transition will occur and how much infrastructu…

>And look at where semis actually park when they're taking their 30 minute and 11 hour breaks

and you believe either the Trucking companies, the Regulators, or Telsa give a shit what works for Actual Human Truckers....

Telsa is looking ahead to full automation anyway so humans are seen as a inconvenience, and if they make it hard on Truckers that will just give them addition ammo for any concerns regulator have in replacing Truckers with Automation. To these companies The fact that is might be hard for Truckers to find a Charging station that falls in line with Hour of Service rules just proved we need to eliminate the humans

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

#124

Post by greglindahl »

baddox wrote: post #96
nimos wrote: post #91

Earlier quoted context omitted.

Already what happens. GM and Tesla use pumped liquid glycol for heating/cooling and some other companies use refrigerants.

Interesting. I did not know that. I always figured they must need to manage heat, at the bare minimum by preventing huge draw for extended periods of time. Do you know where they radiate the heat, given that most Teslas don’t (to my eyes) have visible grill vents?

All Teslas have a grill in the front, it's down low. The battery cooling system is shared with the cabin cooling system.

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

#125

Post by sandstrom »

blhack wrote: post #80
dboreham wrote: post #69

Earlier quoted context omitted.

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.

Wow I would love to see that! Am I reading this right? A electric ship?

This one is in the works: https://qz.com/980207/a-self-driving-electric-ship-will-repl...

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

#126

Post by jjeaff »

Matt3o12_ wrote: post #22
mcguire wrote: post #8

" 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.

I do not believe this is true at all. A lot of people do not supercharge their car often because it is super inconvenient. You need to wait at least 30 minutes to get over 50% charge. One of the great things about electric cars is that you can charge them at home just like your phone and never need to worry about “do I need to fill up to get to work?” You only need super charger when you are on road trips. So most pe…

Ya, my home bill is 13 cents per kwh. I can't figure out why it would cost Tesla $1.

As for the super chargers, I'm pretty sure you can no longer use a supercharger for free if you live nearby it. You are only allowed free usage when travelling.

As for the solar panels on the charging station, that sounds almost useless. Like putting a little solar panel on the sunroof of your model s.

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

#127

Post by flyingspork »

bogomipz wrote: post #121
nimos wrote: post #30

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 pa…

>"The Tesla superchargers currently charge at around 2% a minute up until about 80% which is 40 minutes to hit 80%." I am curious what exactly happens at 80%, does that 2% a minute rate drop off precipitously? If so what is the reason for that?

Lithium Ion batteries are generally charged using a two step process of constant current then constant voltage. https://www.digikey.com/en/articles/techzone/2012/nov/consta... If 80% is the set point to switch over from constant-current to constant-voltage, then yes, the charge rate will drop continuously until it reaches full charge.

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

#128

Post by _ea1k »

bryanlarsen wrote: post #46
_ea1k wrote: post #15

Earlier quoted context omitted.

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.

They would if they were pulling straight from the grid. Go to your power company and ask how much it would cost to surge a mega watt of power at peak times. Those kinds of surges are really expensive to handle. Of course Tesla uses storage and solar to smooth their demand so that they can pay normal rates.

I get your point, and you are probably right somewhere in the country. Having said that, we have industrial plants around here with similar issues, and I'm confident that the rates that they pay are vastly lower than even the $0.07/kwh that Tesla is talking about.

$1/kwh is an extreme outlier and essentially pointless to talk about. There are lots of other options at that price point.

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

#129

Post by _ea1k »

lukealization wrote: post #25
_ea1k wrote: post #14

Earlier quoted context omitted.

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.

> 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.

At the show, they were saying that it did. Do you have some evidence to the contrary?

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

#130

Post by andreyf »

simonsarris wrote: post #64
andreyf wrote: post #33

Earlier quoted context omitted.

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.

Their design has 4/8 ports: https://insideevs.com/wp-content/uploads/2017/12/Tesla-Semi-...

Nice! I guess the width of the wires is the limiting factor? Or a cooling system? Regardless, curious to hear an informed analysis.
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