If only running 2.8A there is no big advantage to using a high drain. I would just get the NCR18650B or the newer NCR18650BF or NCR18650BL. The will handle 2.8A with no problem and give long run times.
In the beginning I used to use only the Panasonic 3400's. Then looking at the graphs and lots of reading I found that the the rated capacity of the 3400 is calculated by running the battery to a lower voltage. However, most low voltage protection kicks in much sooner (2.8-3.0 VDC). So I switched the Samsung 26F and get just as long of a run time for half the cost.
Also, as stated...unless you are using a light that can draw more than what your standard battery gives then you do not need to the high drain cells...ALTHOUGH many are found at a very good price nowadays so it can be worth have at least a couple on hand.
Although the capacity of a cell is the same whether protected or not, protection CAN affect the usable capacity of a cell. Protection always lowers the voltage by a tenth or two of a volt. Because of this, as the cell is discharged, you more quickly reach a point where voltage is insufficient. This has the same effect as lowering the capacity of the cell.
I wonder if I should go for the samsungs just to save cost.
I was told that high drain cells tends to last longer when unused?
Because I read how the panasonic can hold big charges, but lose charge in self drain while the high drain ones don’t discharge themselves even after 1 year unused.
It also reminds me of my eneloops vs eneloop xx where the normal had higher voltage than the xx when unused for a month or so
That is new to me, but interesting. Where did you hear/read this?
I usually don't keep most of my 18650 fully charged, just the ones that are in the flashlights. Li-ion age chemically faster if they are stored fully charged or fully discharged, they lose usable capacity.
For more info about storage recommendations and self drain I like Battery University.
If you were “told” it’s probably male myth with nothing to back it up and a high probability of being BS. Almost every time I read that statement it’s garbage info. Lithium AGE if left FULLY CHARGED - fact. See and READ in the link above.
Of course all batteries age with time, it’s a matter of HOW, HOW BAD, and HOW FAST. In this area there is much speculation and myth but not a lot of reliable information.
Though not discussed for LiOn it is well known in the RC community that the high drain Lipos are MUCH more subject to premature aging (loss of performance-increased internal resistance) if left charged for very long at all. I would suspect, though have no proof, that this may be true for LiOn also.
I don’t store my cells fully charged, so how would I know?
Depends on what you mean by ‘high drain’. If by high drain, you mean IMR, IMR cells tend to age FASTER than ICR cells. The longest lived cells are actually IFR (lithium iron phosphate) cells. These also tend to be high drain (possibly the source of confusion). But their lower voltage makes them less useful for flashlights.
Get the cheaper cells unless runtime is your paramount concern and you dont care about max brightness/throw, you probably wont get to use the capacity of the Panasonic 3400mAh for the reasons stated above, or want to, since you may not be able to draw high current at the low voltage and the C8 will run longer but dimmer in the end. Especially just for a Convoy C8 2.8A it shouldn’t make much difference at all.
I have Samsung 2800mAh 4.3V laptop pulls and 3000mAh Panasonics and I can hardly tell a difference in my Convoy S3/2s when I compare them, and then when I do pay attention, the Samsung 2800s seem to win out barely, because the Panasonics dim earlier… In my L4 I have better performance with the higher voltage cells, and since they are so cheap, you can change em out with another battery when they get low and still have paid less than the Panasonics.
since you guys are talking about the Panasonic NCR18650B, what is your opinion on the NCR18650BE? I’m considering buying these instead of the 3400mAh. I haven’t found much info about them but it seems they have almost the same capacity but a lower voltage drop and they’re cheaper. I’d be using them mainly with 2.1A and 2.8A Convoys. I was specifically interested in the protected version by Keeppower ( http://www.gearbest.com/chargers-batteries/pp_104179.html ). Thanks.
But by the time the protection kicks in, the visable performance has been impacted, and the amount of time from protection to damage is not a huge amount. So yes, but would most of us have pulled the cell out before then anyway? probibly yes.
If you need every last mAh then you will be running lower demand emitters (probibly) so (probibly) less risk. some lights also have a cut off.
A week or two, somewhere hereabouts, I quoted at length from a thorough discussion someone posted at CPF.
There’s no single best point; you can slowly drain down to level X and it will shut off and that’s reasonable, or
you can drain down fast to level X and it will shut off too soon as the voltage will recover quite a bit, or
other things too complicated to remember. Plus battery chemistry plus etcetera.