So compar AH vs discharge C rating. Your large cells vs q30
If there 6ah then compare them to 2 18650
Lager cels mean smaller p number can be used in esk8 but you still need the discharge amps
These cells will be like 8,000mah, easily. They are roughly twice as big as 21700’s. Tesla has stated they will have “6 x the power”, whatever that means (I think they are referring to amp draw- so roughly 60 amps). Anyhow, I’m expecting between 20 and 50 cont ratings from them, perhaps more. With regard to Samsung cells- who can even get them? Who wants to even pay the prices they are currently at? Not I. What are the 40T’s on BulkBattery right now? $6.50? (omg, they are $8.85)! I’ve heard it’s because they (Samsung) are auctioning their cells to the highest bidders.
edit: 4860’s won’t be for bottom mount boards, but I think they will be the most logical cells for top mount once we start seeing salvage companies offering them. it doesn’t matter that they are part of a structural pack. someone will still be able to take them apart faster than Tesla can make them. Their new tabless design is more well suited to high discharge than any other cylindrical cell in existence.
Thanks for the info!
I’m glad the P28A’s are working well for you. They are a good cell.
Interesting that the 3000mAh and 2800mAh cells are giving you about the same range but you’re getting a jump down in range using a 2600mAh cell. So many variables though and different grade cells are all over the place.
Where did you buy your P26A’s? Have you unwrapped any? If so, did they have a free-floating black top insulating ring or was the ring glued on?
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#triggered
Ugh, I still think about that whole thing with M&A BD. Btw, they did end up refunding me, and said they got a new shipment in of the P42a cell, and are sending me a couple samples to test. So that’s nice of them…
Anyway, the p26a I used were from 18650BatteryStore. I picked up a bunch when they were on that Deal of the Day section for like $3.25 a piece. This was a few months ago I think. I didn’t unwrap them. Those strange P42a cells were my first experience in being unsure of the origins of a cell.
After Li-Ion Wholesale got the 28s in I stocked up a bit on those for OW use.
It is interesting to see that there was a difference, and I imagine I probably would have gotten a slight difference in miles if I rode differently near the end of the charge. Maybe… I’m not sure.
Hopefully, when all these gigafactories happen it’ll only be a matter of price for choosing, and not availability. 
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Excellent!
They’re genuine. 
That will be a nice thing to see indeed.
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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.
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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.
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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???
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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.
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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.
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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.
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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.
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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.
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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.
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