[Rumor] new 40700 cell size

The bad news is now what will happen to the 21700?

Watch the video…………

https://www.youtube.com./watch?time_continue=5&v=QQY2vYhysBY&feature=emb_logo

That comes from the twitter guy cited in the video, unless I missed something else (video is such an annoying format, just write an article).

And there are rumours the new batteries will be LFP.

I hope they make packs available to solar off grid users. It would be awesome to have a 100kw pack.

Seriously exciting! But if it is manufactured in-house by Tesla, will it ever be sold in the after market?

Maybe no…but it starts the same as 21700. These cells were intended to be used by Tesla in their vehicles period.
Then they landed nearly everywhere…

[quote=idahofarmer]
They have 10x a 21700 energy. Tesla will use battery pack 1/10th the current size. How is that terrible density? [/Quote]

I don’t think the pack is going to be 1/10 the volume. There will likely be some packing efficiency improvements with the larger cell, but overall volume should remain similar. A 10x reduction in volume would require other worldly improvements in active material specific energy.

The point for them is $$ first. Fewer cells in an architecture with shared components will save time and money in production. I’m not qualified to even guess how much that may be, but I can say pretty confidently the energy density of the cell is not 10x current values.

I guess by “size” he meant “cell count” rather than “volume”.

I guess we will know possibly next week, here is another video posted just 16 hours ago. Talk about massive runtime capabilities in a flashlight! This would be a game changer in the flashlight world!

https://www.youtube.com./watch?v=jK_soSRgMkM

LiFePO4? Glad to listen at. LiFePO4 features an ultra-flat discharge curve, this means their drive trains' performance won't degrade as the battery discharges. This may not mean much in practice because drivers do not usually demand full engine power at all times, but it is worth saying.

On the other hand, hope this means someone with an open mind gets to improve LFP batteries energy density speaking. And when I say lads & lasses with an open mind, I allude to believers in everything's possible.

Because, in all honesty, lithium nickel and other classic “4.2V max” chemistries feature gradually diminishing output voltage curves, which was chosen to help powered device electronics measure battery state of charge (SoC), but it is a drawback in every other respect, particularly when high or top performance is required. Flat discharge curves or constant output voltage is considered quintessential by some (like me), as they model a voltage source. It also makes all available energy in a battery useable regardless of power output.

Providing an example to better ilustrate this, i.e. with a LiFe battery an electric vehicle will provide close to the same performance regardless of battery state of charge, versus with a li-ion battery, whose vehicle performance is sure to degrade as the battery gets discharged:

Or maybe they are using über boost-buck converters (guess not).

LFP needs improvements, in any case. Quite logical when you compare the relative development of LiFe by the big players (pretty scant) versus their development of all the remaining high voltage li-ion variants.

With three 40mm cells, with their wrappers on, the battery tube would have to be over 3.5 inches (90+mm) in diameter. Might make for a nice LT2 lantern. Imagine having a camp lantern that would last 3 weeks between charges? I’m in.

Just wondering, how do LFP-using devices ‘estimate’ state of charge, since the voltage stays mostly flat when getting discharged?

Coulomb counting is an accurate way to get that. I think coulomb counting is also used on smartphones and, despite they use high voltage li-ion cells, in my experience they already reached consistently excellent accuracy with such chemistries. With LiFe it's just a further refinement, if anything (they already have it, pretty sure).

This would be excellent in my opinion, and could be shorter in proportion by staying the same height, would look great. Grooves for legs could be milled in the outside body between cells, it looks like their would be room for those. With the LTmini diffuser, it looks like DBSAR has figured out a way to have upward firing LEDs, so this would be a great evolution of the LT!

So in the end the cells are 46 by 80mm :

https://electrek.co/2020/09/22/tesla-4680-battery-cell-bigger-power-energy/

8 times the volume of 18650, 5 5.5 times of 21700.

More or less read the article and, unless I am missing something and as some people says in the above article's comments, the stuff is mostly click bait.

I remember long ago, when the 21700 cell boom, some people were senselessly arguing overheating problems with bigger cells and bla bla bla. Wrong presumptions, of course.

The only news here is that Tesla is working on reducing overall battery pack costs.

The new format is 46800, round cells with a diameter of 46mm and 80mm long. Doing the volume math, its almost 5½ times the volume of a 21700 and 8 times that of a 18650. The “5x energy” or “6x power” stuff is meaningless click bait.

There's really no point in wanting this inside flashlights, unless you really need or want another completely new format. If you do, let me advise you this may happen again, i.e. Tesla may announce a new larger cell format in the future along with some “new improvements”.

Found our BLF triple 21700 project; lantern/power bank or 3-7 LED whatever type you want. Takes the space of three 21700 with the density of five 21700’s. Potential of up to 27,500 mah.

:+1: :+1: That sounds AMAZING to me :smiley:

That sounds amazing to me as well. 40700 would be better but this definitely looks like it has a chance to kill 4x18650, 3x21700 and 4x21700 formats. If the cells become widely available it will kill them for sure.