Excellent!
They’re genuine. 
That will be a nice thing to see indeed.
1 Like
I just built a 12s4p pack out of Murata VTC6’s and am running a 10s3p of the same cell. Personally, I think they’re bloody excellent cells but I have yet to run any 21’s. I have a stash of Moli’s and will be building a 12s4p for the next build. I also have to say the energy density of the p42a’s just makes them superior, full stop. They’re also less cumbersome to spot weld. I suspect I’ve built my last 18650 pack if I had to guess.
1 Like
So you agree with me
So 4 times the size for 2.5-3 times the disharge. That’s higher capacity but less discharge current in the same space.
What’s that in volume 10 times larger?
You pick best cells for there application cars and PLEV have very difrence needs cars need range are used every day (capacity and life of cells)
PLEV are used over mutch shorter range need hi discharge small and light cells used less often mostly. More similar to power tools.
This is the reason I can’t see a Tesla battry been a optimal choice for a Esk8 there development is down a difrent line to what a average 12s4p esk8 requires.
Plenty of boards and products out there specifically designed for 18650… definitely not dead tech.
5 Likes
I’m expecting Tesla’s first high drain cell, in essence. A doubling of diameter = roughly a 4 x increase in volume, I think. So perhaps they will be 16,000 mah with at least a 40 amp cont rating, but I really expect more. However, 40a cont would be enough to go 2p. That would be fine for a bottom mount enclosure. I just don’t like thick bottom mount enclosures. I think these are very conservative guesstimates. What do you think Tesla is saying when they say “6 x the power”, and why do you think they added all of that copper to the cells? Do you really think they won’t do 40 amps cont???
1 Like
The copper you see are the tabs for the neg there’s loads of thin ones down the coil length instead of 1 that’s in most cilinder li ion. Think of it as a hybrid between 18650 and poutch cells. All in the aid of reducing the IR and increasing the heat dissipation to improve the cells life.
Tesla notes says 5.5x the volume of the 2170 6x the output power resulting in 16% more range.
@Battery_Mooch ratings for the 2170 Tesla cells
Making the 4860 a 60A discharge witch is low output power compared to volume.
As a direct comparison of P42A 5.5x25A=137.5A output power.
Yes it’s a clever new manufacturing aprotch that I hope can be applied in some way with out infringing the copy rights that can improve the construction method and lower IR of other cells with hi discharge chemistry. This could make some incredible hi discharge current cells.
Reducing the ir increases the potential, right? As far as I know, and in existing 21700’s, current has to flow through what is essentially a coil, but with this “tabless” design (which is kind of weird because 4680 has more tabs than it ever had, they’re just folded over) it no longer has to go through the coil/tab/terminal. Now, it’s from any given surface area, to the copper tabs, and then the terminal. That just seems like a really big deal in terms of potential. I think we are getting to the point where we can have the best of both worlds: high drain, and high capacity. Don’t mind me, I just enjoy speculating and visioneering.
Yes that’s why it’s 6x the power with only 5.5tines the volume resulting in a 9% ish increase of discharge power vs volume but that’s other cells out there doing 150% more power to volume like the p42A so Tesla are still a long way behind if thay intended to make a super hi discharge cell.
So there still well and truly in the low discharge catergry as My opinion. I am expecting long cycle life with the improved thermal cooling options that come with this new packaging techneak.
What are the internal differences between a high drain cell, and a high capacity cell? I don’t think it’s a difference in chemistry as much as it is a difference in physical layout. I think they have to use thicker (edit: copper collector, thinner anode material = less capacity)cathode and anode layers in high drain cells, but I also think the only reason they have to do that, is because of how the current has to flow through just a single tab. So, current originating at the very end of the roll, has to travel the entire length of it to reach the tab. Not so with the 4680’s.
What maths gave you “9%”? I’m expecting more.
Definitely the differences in the current collector thickness you mentioned but also the number of tabs (some existing cells use more), the amount and type of conductive fillers, the anode and cathode material porosity (tortuosity), and other stuff like that.
There are chemistry differences too though. For a high current rated cell a manufacturer might trade off capacity for faster ion diffusion rates through the materials (to help prevent lithium plating) and things like that. Different anode and cathode materials can be used to get the desired balance of capacity, performance, cycle life, etc.
2 Likes
It’s been challenging trying to learn these things on the internet. Is there some secret wealth of information somewhere about these things outside of universities? I’d like to see some of the chemical formulations they use, and how they vary.
Google is the way to go, really.
Try searching for the MSDS/SDS for the cells you are interested in. It gives you the chemical composition of the cell.
Many are wildly vague, to protect the “formula”, but some are very specific. None will tell you specifically what binders and additives are used though as though as they are important trade secrets.
Industry and academic papers on cell aging or degradation often discuss chemistry in a lot of detail. Same with papers on thermal runaway.
I sometimes have to go through 20 search results pages before I find some good stuff but you’ll quickly learn what terms to use to get the best hits right away for the type of stuff you are looking for. For example…you might search for “best li-ion chemistry for cycle life” but the best hits for that topic might come from searching “li-ion aging mechanisms”. Use the same terms you see in the papers you find as those will probably be the terms that other papers use too.
Ignoring terms like LiPo, IMR, INR, ICR, and others that are marketing terms or model number prefixes (and not a chemistry) will help a lot. Use the same chemistry acronyms that industry and academia use; LCO, NCA, NMC, LFP, LTO, etc. That will help focus the search results on the papers you really want and away from the hobbyist web sites.
6 Likes
Check out “The Limiting Factor” YouTube channel…lots of good stuff there. Also check out videos that analyzed Tesla’s battery day announcements. Many went into a lot of detail about cell chemistry and the tradeoffs involved.
Papers on thermal runaway often talk about chemistry and construction too. NASA has some great workshop papers.
2 Likes
I was just about to share this video, ha. :#10 Tesla Cathode Deep Dive // Hardcore Particle Engineering - YouTube
Simply searching “LCO, NCA, NMC, LFP, LTO” brought the channel up.
Great stuff.
1 Like
Subscribe to Intercalation Station too as that newsletter has links to all sorts of great papers and commentary that leads to even more stuff.
The References section of the papers you read is really important too! Each paper can have up to dozens of other papers listed that you can search for. Many need to be purchased but lots of them are free. If one web site says you need to pay then keep checking. Sometimes another site has it for free.
2 Likes
There are lots of new technologies coming in the near future.
Both fossil fuels and electric power are evolving at a very fast pace.
Exciting times.
1 Like
Every thing chemistry materials used manufacturing proses it’s all a compromise to achieve there goles of a balance between cycle life, AH, discharge, form factor, cost, saving the planet and any other thing thay consider.
10A for a Tesla2170
6X the power so 10Ax6=60A
5.5x the volume 60A/5.5=10.9A
10.9 is 9% more than 10
It’s all in the advertising, manipulating the numbers to sound better 6x the power sounds better that’s why thay say that not a 9% more power. Same as 50% extra free dose not mean 1/2 of the item is free only 33% of the thing you looking at.
The second half of that quote, “as much as it’s a difference in physical layout”, is more relevant than the first half. For example, if you were to take Tesla’s current 21700’s, and give them a thick enough copper collector, they’d be high drain. They’d be capable of outputting what used to be short bursts (20a), continuously. If you add 9% more ampacity to their existing 21700’s, they’d only be good for about 11 amp’s cont. How long do you suppose current has to flow in existing batteries before it reaches the tab?
It looks like several feet to me. That’s getting cut down to inches. 4680’s don’t have to travel more than 80mm’s to reach the tab, where as before it could be as much as several feet (800mm’s). That’s a ten fold decrease in pathing. It has to be much better than 9%.
edit: It may indeed be just 9%. I guess it’s called the “electrode to current collector ratio”, and they can make it whatever they want. I imagine the new design will allow Tesla to use a thinner copper collector, and therefore a thicker anode coating layer for more capacity because the “tabless” design will allow it, and they don’t need more than a 50 or 60a cont rating anyhow. It’s interesting to note that the anode layer seems to cover both sides of the current collector. 50 or 60a would be ideal for esk8 for a 46mm wide cell.
1 Like
Yes have many thousands of them, have big battery’s and they only go from 20 to 80% hopefully they will last a long time.
Do want to build a 21700 battery they look ideal cells.
1 Like
But that’s at the cost of the same volume and weight of 5.5p pack that’s huge for sutch a low discharge.
Your arguing agains the figures in Tesla’s press release. You can want it to be higher but until there’s some in people hands like mosh then that’s all we can go off. Cars and Plev’s have very difrent requirements from battery’s. e sk8 we are reliant on piggy backing off the tech that has similar requirements from a power source such as power tools. E sk8 it’s too small of a market for companies to recoup the cost of research and development of battery’s. I don’t see Tesla ever been The saviour to push your boundaries that you’re looking in e sk8 as there direction is difrent.