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18650 Batteries
- Thread starter NotTarts
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- Tesla Inc.
stopcrazypp
Well-Known Member
18650s aren't going anywhere. It's still the cheapest per kWh and the most energy dense. That will ensure a market for them exists. Tesla alone will have a significant contract (because Tesla uses a lot in even on car). I find it much more likely that Tesla moves on to a different form factor (if a better one comes along) before the 18650 is truly dead.
And from the early reports, sales of the Surface isn't going too well. The whole tablet "replacing" the laptop is greatly exaggerated. Yes, annual laptop sales figures are not longer growing because of tablets, but I think it's pretty clear right now that a tablet is an additional device, not a replacement for a laptop. So while the tablet may get more use and has a much faster growing market, most people still have a laptop anyways.
And from the early reports, sales of the Surface isn't going too well. The whole tablet "replacing" the laptop is greatly exaggerated. Yes, annual laptop sales figures are not longer growing because of tablets, but I think it's pretty clear right now that a tablet is an additional device, not a replacement for a laptop. So while the tablet may get more use and has a much faster growing market, most people still have a laptop anyways.
Zzzz...
Member
During Roadster development Tesla released (or it got leaked) technical analyses of using 18650 form factor for automotive battery packs. I have scanned the document as opposite to actually reading it, but I remember they mentioned as advantage that smaller batteries(18650) do have high surface area and that would be a big help for thermal management.
My guess would also be that using smaller batteries could provide some safety benefits, like if one cell got shorted, energy release would be relatively small. As opposite to the case of bigger cell with same chemistry.
I also recall that I heard/read somewhere that those 7000 cases help with structural rigidity, but not sure about this one.
> cells made for automotive applications are exactly the same as ones made for notebook/tablets (NCR18650A) [or not] [Zzzz...]
Aside from the main issue being debated here, is it not the case that this particular form factor, essentially the popular "AA" cell size but a bit bigger, is referred to as a "Laptop battery" merely for historical reasons?? That in fact NO laptops for many years have continued to use these individual cells, choosing instead plastic-bagged cells that are housed in custom shapes that fit into laptop/notebook cases. I have 5 modern laptops which I doubt could hold 18650s. Only my old ThinkPad has a battery box thick enough for these cylindrical cells, but I sort of doubt any are in there. Maybe old CP/M or Dos3.0 laptops (and *those* were LAPtops!) actually used 18650s.
Which raises the question who is using 18650s today, aside from TM??
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Aside from the main issue being debated here, is it not the case that this particular form factor, essentially the popular "AA" cell size but a bit bigger, is referred to as a "Laptop battery" merely for historical reasons?? That in fact NO laptops for many years have continued to use these individual cells, choosing instead plastic-bagged cells that are housed in custom shapes that fit into laptop/notebook cases. I have 5 modern laptops which I doubt could hold 18650s. Only my old ThinkPad has a battery box thick enough for these cylindrical cells, but I sort of doubt any are in there. Maybe old CP/M or Dos3.0 laptops (and *those* were LAPtops!) actually used 18650s.
Which raises the question who is using 18650s today, aside from TM??
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Johan
Ex got M3 in the divorce, waiting for EU Model Y!
stopcrazypp
Well-Known Member
I think you are mistaken. Any laptop that references an x-cell battery (typically 3-cell or 6-cell or 9-cell or 12-cell) has 18650s. The battery pack will have a long shape (rather than a flat one), and it pretty obvious they can fix x-amount of 18650s cells in that x-cell pack. There are still plenty of laptops that use these; I can feel safe to say "most" (google "6 cell laptop battery" for example).
Pouch cells (usually called lithium polymer) are used mainly for tablets and laptops without replaceable batteries, although they are gaining some use in replaceable laptop battery packs too (where thinness matters).
Zzzz...
Member
18650 cells have less then 2cm in diameter...
The things like this battery, you can see from the name it uses 18650 cells and it fits a lot of models from Acer. But same true for virtually all other manufactures of laptops(with exception of Apple), and most of their model lineups.
On the other hand, raise of Ultrabooks(and MacBooks) plus growing popularity of tablets might lead to decline of 18650 market in mid term.
The things like this battery, you can see from the name it uses 18650 cells and it fits a lot of models from Acer. But same true for virtually all other manufactures of laptops(with exception of Apple), and most of their model lineups.
On the other hand, raise of Ultrabooks(and MacBooks) plus growing popularity of tablets might lead to decline of 18650 market in mid term.
JRP3
Hyperactive Member
Here are the other graphs from Panasonic:
Not sure what to read from that. The charge graph says 4.05V is ~80% capacity, but the discharge graph is measured from 4.2V so it might not be accurate.
omgwtfbyobbq
Active Member
Just to provide another POV, here's some more information on cycle life.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110003627_2011001727.pdf
Specifically...
I think it's possible that Tesla is using a slightly different formulation, but that low discharge rates and depth of discharge really improve cycle life compared to cycling at 100% dod.
I wish the Pansonic paper had more than one year of calendar life losses, but that's hopefully logarithmic decline that stabilizes around ~60%-70%.
It doesn't look like cycling doesn't hurt capacity much. I guess the moral of the story is you can drive the crap out of the car, just make sure to do it at c/5 or less discharge/charge rates and try to keep the depth of discharge near 50%.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110003627_2011001727.pdf
Specifically...
I think it's possible that Tesla is using a slightly different formulation, but that low discharge rates and depth of discharge really improve cycle life compared to cycling at 100% dod.
I wish the Pansonic paper had more than one year of calendar life losses, but that's hopefully logarithmic decline that stabilizes around ~60%-70%.
It doesn't look like cycling doesn't hurt capacity much. I guess the moral of the story is you can drive the crap out of the car, just make sure to do it at c/5 or less discharge/charge rates and try to keep the depth of discharge near 50%.
DrTaras
R254->R725->S->X->M3->M3P-->R2020?
Interesting article that flips this 180 degrees:
Old laptop batteries could power slums
http://www.bbc.com/news/technology-30345221Similar threads
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