A muggle-type /beginner question. Not specific to but, lets use 18650’s as examples.
Some 18650’s are capable of producing low current; ~10A and under. Others are capable of producing much higher current ~35A and above.
Is there a rule of thumb or formula to match a high-current output cell to a certain design light/LED(s)/driver in order to maximize performance? Conversely, what criteria matches a low-current cell to a light that’s incapable of handling higher current cells?
Seems like I’ve seen chatter to the effect that running a cell capable of high amperage output in whatever light was being discussed could damage the light’s driver/LED. Such a light would seem to call for a cell incapable of producing high current in favor of high capacity.
Generally, a good quality light that has some form of regulation won’t get fried from a cell that CAN supply that much current. Power “capsules”, or cells, contain a finite amount of power. They’re more like passive power supplies, only supplying what the drivers or regulations try to pull from them.
In a direct drive light, dumb circuit, or a short, the cell’s “full potential” is allowed to course through all entire circuit, impeded only by whatever resistors are on the line.
A driver is like putting a variable valve on a keg, a dumb circuit/short is like cutting the bottom out of the keg.
One of the very few ways a well driven light will fry the circuit is if it’s poorly designed, or the driver has some auxiliary bypass that someone didn’t program properly, like what happened with some iterations of the Wurkkos ts10. It was drawing WAY more power than intended on turbo.
**addendum,
GENERALLY, (I tend to use that word alot) it should be safe to use a cell that is rated much higher than a driver will ever ask for. As long as the minimum/macimum current and voltages are met, a good driver will know how to allocate that power.
In short, buy what you’ll need. If a light only drives up to 1A, then you don’t really need a cell that provides 5A of current. If you’d like the wiggle room to use that cell in other lights that MAY require 5A, then just get the 5A cell for peace of mind.
I bet you wear mismatched socks, but one dirty and one clean. I’m just kidding, lol. I’ll do cell matching only for multi-celled lights, but will rotate the positioning of the cells to “balance” the wear on serial batteries.
At the moment the only multi-celled light I have is my SK05 Pro, when the batteries in that need replacing I’ll be buying two for that specific light and they’ll be labelled and married.
Generally (there’s that word again!), due to the design and construction of the lithium cells we use, cells are either high(er) capacity OR high(er) current output options.
High current capability allows the cell to maintain a voltage under load, plus due to the lower internal resistance, it’ll heat up less, which makes it more efficient.
Due to this, you’ll see from the mooch tests, that sometimes cells with lower capacities, actually perform better than higher capacity cells.
I try to put my high(er) current cells in lights with FET drivers despite very rarely using turbo, simply for the reason I’d prefer not to “stress” the cells excessively.
The cells I do have mild concerns over are these 10180 to 10440 size cells which get put into lights and are run at multiple C outputs…
That’s the kind of info I’m looking for. Appreciate the response.
When purchasing LiIon cells, I’ve tended toward higher capacity rather than high current. The vast majority of my lights are single emitter designs. None are really what might be considered hotrods. The only light I have that might benefit from higher current is my three emitter C8F.
Cell selection based on the technical requirements of light designs is a subject that might be of interest to those new to the hobby. Perhaps a synopsis sticky could be created?
Do bare in mind some of the details of “best” cells discussed on this forum are really minute gains and not really noticeable in real use.
For cell testing, I don’t know anyone who’s contributed more to this community (and vapes, ebikes, etc) than Mooch, see the reccomended cell lists here:
One important thing to keep in mind with direct driven lights (FET) is the LED maximum current/power handling limits so that You don’t burn the emitter. A FET driver on full blast will pass all the cell can produce to the LED (minus the whole circuit resistances) and this can go well over the limit.
Take a look at @koef3 LED tests, some of them take the tested emitters over their limits and not that rarely are those limits within what current cells offer
Don’t forget cold temps way below freezing. Or a cell that is not fully charged or getting older. You are going to have voltage and current sag in freezing temperatures as the chemical reactions slow down. So if you want turbo from lights that are stored in freezing temperatures generally you want batteries with higher current capabilities. If you don’t need turbo then higher capacity is probably better. In the18650 size there are plenty of 3500mAh with a 10A rating today. So I wouldn’t get anything less than that.
I’m just kidding, lol. I’ll do cell matching only for multi-celled lights, but will rotate the positioning of the cells to “balance” the wear on serial batteries.