fyrstormer
Banned
Well yes, that's based on the same structural integrity that makes them more crash-worthy too.
Tesla's gigafactory dropping 18650's and going with 20700 - per Elon Musk
- Thread starter billcoe
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If one thinks about it you see more cylinders in the market than squares in all sorts of products like beverages, canned food, etc and the reason for this is two fold in that you don't have to try and align machinery to deal with squares and also deal with corners of them in production plus devices that use them if they were all squares making flashlights to use square cells would get more expensive as you probably couldn't turn them on a lathe easily. If you think about it you don't hardly see any square batteries in many chemistries out there in the single cell variety only batteries that have several cells in them are square these days (like 9v, and 6v lantern batteries) and even these have round cell inside of them. I would like to see prismatic cells cheaper than cylindrical ones and see a common size/shape of them such that people will start making products to use them across the board as the prismatic cells are way too many sizes and shapes and I think even times the ones that are supposed to be the same size/shape..... aren't exactly. It may be possible that a breakthrough in batteries comes with one that doesn't have to be concerned about the chemicals wanting to leak in use and also when used up and/or aging a lot and if this breakthrough happens then we could even see flexible "bag" type batteries that you can make fit into a similar volume/size holding container.
ChrisGarrett
Flashlight Enthusiast
Here's a recent article about a 'tour' of the new Gigafactory.
http://www.bbc.com/news/technology-36893104
"We had just had a tour of the new Gigafactory, Tesla's $5bn (£3.8bn) 3,200-acre battery-manufacturing plant that has already begun production but will not be in full swing until about 2020.
At that point, it will have the largest physical footprint of any building in the world.
By making battery cells here, Mr Musk hopes he will be able to innovate faster and cut out about 30% of the cost.
The factory is a tie-up with the company that already makes Tesla's cells, Panasonic."
Chris
http://www.bbc.com/news/technology-36893104
"We had just had a tour of the new Gigafactory, Tesla's $5bn (£3.8bn) 3,200-acre battery-manufacturing plant that has already begun production but will not be in full swing until about 2020.
At that point, it will have the largest physical footprint of any building in the world.
By making battery cells here, Mr Musk hopes he will be able to innovate faster and cut out about 30% of the cost.
The factory is a tie-up with the company that already makes Tesla's cells, Panasonic."
Chris
FroggyTaco
Flashlight Enthusiast
Or perhaps people have power yard tool needs beyond a 100' cords reach and/or don't want to deal with having to spend 1/2 your time managing the cord & just want to go use the tool like a gas version but even easier since there's no starter cord to pull(how many times?), no choke to manipulate & time to let the engine warm to have a stable idle, no hot exhaust to have to worry about brushing against & getting burned or perhaps starting a fire, no gas to have to tote around & refill & potentially spill, no gas to have to mix with 2 stroke oil & hope you use it up before it goes bad...etc.
Both sets of power(Gas & Battery) have their place in the world. I personally have overall a small & highly infrequent "yard" power tool needs & being able to quickly, conveniently use battery yard power tools & not have to mess with oil changes, gas, 2 stroke mix, gummed up carbs from lack of use, etc has been refreshing. I tried it this year & was astonished at how well they worked relative to the power source.
FroggyTaco
Flashlight Enthusiast
Depends on the region. Areas with hydro, geothermal, solar, or wind turbine electrical production have far lower over emission "costs" overall. Also as more higher efficiency & lower emission natural gas plants come online will help as well.
FroggyTaco
Flashlight Enthusiast
Exactly. Ratio of a circle area to a touching square area is a constant value (π/4) no matter the size they are. Now we know who was kicking butts at school instead of studying
There is another issue: generated heat is a function of volume, but dissipated heat is a function of surface area. That is the larger the battery the more it is prone to overheating. More of that, we have no idea about the ability of Li-Ion layers to transfer heat in lateral direction (from layer to layer). So, theoretically, a large battery may be relatively cold outside, but melting in its core.
How does the larger capacity & therefore likely lower C discharge rate of the larger cell affect heat build-up? I would think that would offset that concern. Of course there will be less overall 20700 cells than 18650 cells so there will be a higher wattage draw per cell but I'm guessing the capacity increase will outweigh the increased current.
Seems it's not going to be 20700 cells after all:
http://fortune.com/2016/07/27/tesla-bigger-battery-gigafactory/
The king is dead, long live the 21-70. :bow:
http://fortune.com/2016/07/27/tesla-bigger-battery-gigafactory/
The king is dead, long live the 21-70. :bow:
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If this is true then you could replace 7 layers of 18650s with 6 layers of 21700 batteries and be about the same height.
SubLGT
Flashlight Enthusiast
Interesting comments from Tesla about their battery choice:
http://cleantechnica.com/2016/07/27/10-key-takeaways-tesla-gigafactory-opening/
JB: "We've spent a lot of time on this actually. It's kind of interesting. There are a bunch of tradeoffs. There are some things that get better when you make the cell size bigger, and some things that get worse. 18650 was sort of an accident of history. That was what was standardized for early products. So we revisited all of those tradeoffs and came to this size, which is quite a bit bigger. If you have them next to each other, the actual volume of materials inside is substantially more. And overall it's about cost optimization."
Elon: "It really comes from the first principles of physics and economics. That's the way we try to analyze everything. To say like if no cell existed in the world, what size should it be? What is the size that would achieve the product characteristics we're looking for, but would be fundamentally optimal? 18650 is not optimal."
http://cleantechnica.com/2016/07/27/10-key-takeaways-tesla-gigafactory-opening/
JB: "We've spent a lot of time on this actually. It's kind of interesting. There are a bunch of tradeoffs. There are some things that get better when you make the cell size bigger, and some things that get worse. 18650 was sort of an accident of history. That was what was standardized for early products. So we revisited all of those tradeoffs and came to this size, which is quite a bit bigger. If you have them next to each other, the actual volume of materials inside is substantially more. And overall it's about cost optimization."
Elon: "It really comes from the first principles of physics and economics. That's the way we try to analyze everything. To say like if no cell existed in the world, what size should it be? What is the size that would achieve the product characteristics we're looking for, but would be fundamentally optimal? 18650 is not optimal."
SubLGT
Flashlight Enthusiast
From 20700 to 21700? Samsung will be happy to hear this.
"...Samsung SDI also unveiled a battery pack product equipped with 21700-type batteries, noted for their upgraded energy capacity compared to previous cylindrical types. The 18650 battery, or rather the small cylindrical battery of 18mm diameter and 65mm length, has been in dominant use until recently. However, the creation of new battery applications has boosted the demand for high capacity batteries. In response, Samsung SDI has come up with a battery that has upgraded a maximum of 35% of energy volume, now known as the 21700 battery, and has successfully applied it onto e-bikes for the first in the world.
The 21700 model can have various applications other than e-bike, such as in electric tools, laptops, and more. It is expected to become the new standard in small cylindrical battery usage…"
http://www.greencarcongress.com/2015...6-samsung.html
"...Samsung SDI also unveiled a battery pack product equipped with 21700-type batteries, noted for their upgraded energy capacity compared to previous cylindrical types. The 18650 battery, or rather the small cylindrical battery of 18mm diameter and 65mm length, has been in dominant use until recently. However, the creation of new battery applications has boosted the demand for high capacity batteries. In response, Samsung SDI has come up with a battery that has upgraded a maximum of 35% of energy volume, now known as the 21700 battery, and has successfully applied it onto e-bikes for the first in the world.
The 21700 model can have various applications other than e-bike, such as in electric tools, laptops, and more. It is expected to become the new standard in small cylindrical battery usage…"
http://www.greencarcongress.com/2015...6-samsung.html
sidecross
Flashlight Enthusiast
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FroggyTaco
Flashlight Enthusiast
I'm all for the best engineered size cell rather than the "what we have been using for a long time so it's a standard" cell.
So many "standards" throughout our lives are based on archaic & now obsolete/irrelevant platforms that for w/e reason aren't brushed away in favor of the new.
This will also have a positive trickle down effect on all sorts of battery powered high drain devices & create the opportunity for new battery powered devices to come to fruition.
So many "standards" throughout our lives are based on archaic & now obsolete/irrelevant platforms that for w/e reason aren't brushed away in favor of the new.
This will also have a positive trickle down effect on all sorts of battery powered high drain devices & create the opportunity for new battery powered devices to come to fruition.
SubLGT
Flashlight Enthusiast
http://electrek.co/2016/07/28/tesla...and-tidbits-this-is-the-coolest-factory-ever/
Excerpt:
"...When it was my turn, I asked the status of the "20700" battery that has been reported to be going into Model 3…….
Excerpt:
"...When it was my turn, I asked the status of the "20700" battery that has been reported to be going into Model 3…….
- They actually changed the size to 21mm diameter and a 70mm height. They also got rid of the trailing '0' so the name of the battery that will be going into the Model 3 is the '21-70′
- JB Straubel says Tesla developed this battery this size by starting without preconceived notions. They then optimized for efficiency, size and output. The 18650 standard was called an accident of history though it had served Tesla and others well. Tesla says it predicts that this new 21-70 battery size will become a new standard.
- The half centimeter height increase for the car packs would be offset with more efficient battery packaging which will make the packs actually the same thickness or less than current packs and obviously with a higher energy density….."
Drift Monkey
Newly Enlightened
Anders
Enlightened
Double post.
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Anders
Enlightened
- Christina Lampe-Önnerud at Cadenza Innovation-""Elon Musk and I are actually of the same opinion when it comes to small units. But while his idea was to take laptop batteries, put them together in a trough and add the safety on the outside, we've placed everything within an aluminum container.""
http://nordic.businessinsider.com/t...an-increase-the-range-of-teslas-by-70-2016-7/
http://nordic.businessinsider.com/t...an-increase-the-range-of-teslas-by-70-2016-7/
etc
Flashlight Enthusiast
I cannot wait to put one in 6P with an aftermarket body. The body will be as big as the head.
The ~10% increase to the 18650 size is not unique to Tesla, e.g. last year Samsung SDI announced a 4750mAh 21700 cell (vs. Telsa 20700) targeting the e-bike market, see below
According from the latest press conference because of Tesla/Panasonic's grand opening of the Gigafactory today, they are going to use 21700 cells instead of 20700 cells like they previously said.
I don't hope we will be seeing two new standards, both 20700 and 21700. Maybe it's just a matter of how they round off the numbers and they are all around 20.5 mm in diameter. Or maybe 20 mm is just the diameter without plastic shrink tube and 21 mm is the diameter with plastic shrink tube.
http://insideevs.com/highlights-tes...nference-featuring-musk-straubel-panasonic-vp
Highlights From Tesla Gigafactory Press Conference Featuring Musk, Straubel, Panasonic VP
Battery Format
Straubel:
Tesla CTO J.B. Straubel said:
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FroggyTaco
Flashlight Enthusiast
Or maybe the 20700 was a smokescreen to through off industrial espionage or enable better negotiations for some contract/deal/terms. Or maybe further testing & tech has came about recently that it's now feasible to employ the 21700 vs the 20700 design. Also perhaps the highly unanticipated demand gave them the freedom to commit more R&D money that helped make the change.
