It can…if the heat can’t escape and the temp rises high enough to trigger the decomposition of the different materials and eventually force the cell into runaway. This goes for any cell chemistry.
If there’s a short-circuit then there’s enough heat to bring a localized spot of cathode material up to thermal runaway almost instantly and that can propagate through the cell. But for other situations, creating less heat, the temp never gets high enough in any of the hotspots to start runaway.
If that paper used an adiabatic test chamber then the heat had nowhere to go.
It’s my understanding that they are NMC811 or NCA…not a higher nickel cell. The BAK 5800mAh and 6000mAh add some silicon to the anode for their capacity increase. The other companies might do the same, I do not know for sure.
The ultra-high nickel cells aren’t time bombs though. They might be more susceptible to TR but that doesn’t mean it will happen easily. None of the manufacturers can sell a cell that does that and all cells will have to pass UN38.3 testing and many will pass more stringent testing before being sold.
Why is adding silicon bad?
They’ve solved the cracking issues with flexible binders and careful particle formation. Well, for partial-silicon anodes that is.
Dammit, am I in a battery argument with battery Mooch?
This is just like that time I told J.R.R. Tolkien that actually the Eagles could have flown Frodo in to Mordor, or when I told Neil deGrasse Tyson that Pluto wasn’t real. (I was talking about the cartoon dog, Neil, stop showing up at my house!)
I wasn’t trying to be. I’ve been trying to end every post with some version of “but idkk” lol
Just talking about batteries. Concerned about the potential tradeoffs of higher capacity
Argument? Never thought we were anywhere near that. Just two people geeking out about li-ion.
Concern can be a very good thing. Discussion is always good. It leads to the decisions each of us can make regarding the cells we’re willing to use and the ones we’re staying away from.
I guess my thoughts for this are that we should definitely be checking out the available research papers (I read hundreds a year) but also be careful how we apply the info they contain. The details really matter and there are so many of them…dizzying sometimes.
I also wonder to which extend battery adapters hinders batteries in flashlights to get rid of their heat. For example on left of the photo below is a 26650 > 21700 adapter that came with one of my (26650) Astrolux flashlights. It basicly wraps the whole side of a 21700 with a 2,4mm thick ‘plastic’ sleeve, which I can’t imagine is beneficial for the temps of the battery.
On the right of the ‘plastic adapter’ is what Simon/Convoy sells as 26650 > 21700 adapters. Although ‘air’ also isn’t the best conductor of heat, I like to think that this way there is less heat trapped by the ‘adapter’ than in comparison with the (thick) plastic sleeve.
So that is maybe also something to consider if you are running a battery in combination with an adapter in a (single cell) ‘High Lumen/FET’-flashlight.
I agree…
Any adapter will certainly be worse than having the cell directly touching the side walls of the light. How much worse would depend on the adapter and what kind of fit the cell had in a light without an adapter.
But while a tight-fitting cell (no adapter) is better for pulling heat from the cell it increases the risk of the plastic wrap being damaged. In certain circumstances that could be a disaster.
Any material that touches the cell and the inside wall of the light will conduct more heat away from the cell than the same spacing of air. Air is a truly fantastic insulator.
IMO that white sleeve will keep the cell cooler than than the two black rings. Maybe only a degree, I don’t know, but it would be cooler. I just don’t think there’s enough space for convective air currents (which can help cooling) to flow.
Definitely something to consider. Would be nice to have some hard data but creating it would be tough.
@Wingman…wait a sec…that white sleeve seems to have a ridge around it that prevents it from having a snug fit in the light. This creates an air gap, lessening the amount of heat the sleeve can transfer to the light.
I still think the sleeve/air combo is better than almost all air (with the black rings) but maybe not by much.
Indeed; most likely(?) way to do that would be to test it using small thermocouples, but to keep circumstances as close to reality as possible, you would need (at least) to drill a hole through the flashlight for the wire of the thermocouple (and preferably close it airtight again). Also important (and interesting) to decide where on the battery to place the battery (inside the sleeve/at the side or at the open top/bottom), although it will heat up everywhere in the end.
And there are a (probably) a lot of other variables to take into consideration to get accurate/consistent readings.
You are right, the white sleeve has a small (silicone?) O-ring, probably to keep it from rattling (I guess).
A few days ago I ordered a set of 2 extra ‘white sleeve adapters’ on Aliexpress and as far as I can tell those haven’t got such an O-ring. I’m curious to find out if they have a tighter fit than the one I already have.
The standard is halfway up the side.
The ends will be cooler but if measuring the same way for each sleeve, just comparing the differences in temp (vs absolute cell temp), then you could mount it anywhere it wasn’t being affected by the end contacts or something else touching nearby.
IMO this could be done very simply, just using a cell on its own (not in a light) in the different sleeves with a thermocouple. If the cell+sleeve is kept in a small space (just wrap with a cloth or put in a toilet paper tube or whatever to limit air flow) during the test you could get some pretty good data for a bare cell and a cell with each of the sleeves on.
You would not get the effect of the wall of the light pulling out heat but it appears that the full length sleeves have o-rings that limit contact anyway.
Hmm…a sleeveless cell would lose a lot more heat to the light’s wall though. But at least you could find out how much hotter a cell runs with a sleeve on vs off in a small space. Probably not by much unless it’s a very short duration, high power run?
This should probably be in its own thread so more can chime in?
My main concern is that the small format high performance cylindrical lithium ion battery will disappear.
Even tool batteries are starting to use pouch cells now. Idk how that’s going to go. People seem to love them but my experience with LiPo is that they don’t last nearly as long before they start to show their age. I wonder if that’s going to be an issue down the road.
And then fast charging. What’s the tradeoff for a battery that can charge in 15 minutes? We assume a battery that can fast charge can fast discharge but can it? I think theres probably a tradeoff coming there
So many millions are made every day that IMO it will be quite a while before that stops, if that ever happened. I think there will always be a need for round cells of all sizes.
Yea, I agree, the cycle life for the typical low-cost “commodity” LiPo’s being sold for hobby use is very low. But the good LiPo’s (phones, tablets, etc) can be used for years. A lot depends on the level of abuse vs the ratings too though.
Any cell can be fast charged and every cell will have a shorter life if that is done. The ones with a fast-charge rating might be engineered a little differently to handle it a bit better though.
Most cells with a high charge or discharge rating will also have a high rating of the other since the internal resistance needs to be low for either. It varies by cell but as a general rule it’s true.
For sure, lower resistance benefits both charging and discharging. But what I’m (failing at) saying is…
So, charging and discharging are two different things, obviously. Two different processes. Linked together like conjoined twins, of course, but different things, in many many ways. Not going to list any, I’m sure you would agree, and can list a lot more than I can. So, if that is the case there must exist a variable that impacts one process in a different way than it impacts the other. And of course there is. Again, no reason to go through the list.
The thing I can’t list at the moment, but that I believe, just based off probability in this infinite universe must exist, has to exist, are the variables that when adjusted will positively impact one process but in doing so must negatively impact the other process. And I wonder if, with one process a higher priority than the other, how far we will adjust those variables and what the impact might be.
But, maybe that decision is a million years in the future. Maybe we can improve both processes at the same time until the end of the universe before we are ever required to adjust those variables.
I don’t know which is true. What do you think? I would guess youre leaning more towards the second one? That we can improve both processes at the same time, for at least the foreseeable future? Just based off your last response.
I can’t think of anything that could improve charging in some way but negatively impact discharging in some way, and vice versa.
Those two things are just different directions, but the same pathways, for the ions and electrons. Something that hurts charging performance would probably also hurt discharging performance. Same for something that helps.
Isn’t that a DNA-related ratio? Or did you mean neutron-proton?
I wouldn’t know about how either might affect things here.
I’m not sure we can make the assumption you’re making but it’s interesting to consider.
The coulombic efficiencies for charging and discharging are slightly different for li-ion but I don’t remember enough regarding why and what that might mean for our discussion.
Negative/positive. Capacity of the negative electrode vs capacity of the positive electrode. Cell balancing. Ex, when the anode is larger than the cathode, like it usually is with high capacity cells, N:P>1.
Maybe theres a more frequently used term? It is weird that they would use “negative” and “positive”, but that’s what I see written.
Ahh…okay, thanks. I haven’t read about that in a while, forgot about it. Critical for cell designers though!
You’d have to do some pretty serious research to determine if that ratio affected whether doing something to improve a charge metric would negatively affect a discharge performance metric, and vice versa.
I think I may be reading the charts wrong but can you clarify your comment on the Samsung 50s and it running longer than the f60? It said that the 50s ran longer but the chart shows over 5 amp hours on the f60 and under 5 for the 50s(looking at the 5amp runtimes mostly)
Trying to figure out if I should splurge a couple more dollars for the f60 in the convoy m21h. Zero air shows the 70.3 runs at 7.75 amps at 100% and the next step down at 1.84 amps which seems perfect for the f60 to take advantage of the extra capacity based on your comment. If I tend to turbo more than usual would the 50s be the better buy or a wash?
