I’m thinking of buying new cells for my light BUT one of my biggest issues is knowing which cell(s) are safe to use with it.
For example I’m buying new 18650s for my SC65. I know that 18650s have a few capacity sizes like 2.8Ah, 3Ah, 3.5Ah and 4Ah. I also know that higher capacity usually means it is rated to discharge less amps. I could easily spend sometime just looking at all 18650s of a similar capacity to see in general how much Amps they can safely discharge into the flashlight. Is there a website that list say all 18650 cells that allows me to sort by amp so I can know which cells I should buy for my light? Same with other cell formats like 21700 and related as well… Or am I forced to read spec sheets of every cell?
Generally, a battery will only discharge the amount of current ‘pulled’ by the driver+LED. Even if you have a high discharge cell, the flashlight will only draw the amount that is needed. For example, a 10A battery is more than enough for the SC65, but you can safely use a 25A battery in it, you will just be losing capacity.
Also, all batteries have a max discharge rate, even if the driver “requests” more current, the battery will only discharge at its max rate, not more.
Only safety issue regarding batteries are specific to certain models, such as the TS10, which has reports of LEDs burning when using turbo too much using a H10 which can discharge at 10A.
Also, all batteries have a max discharge rate, even if the driver “requests” more current, the battery will only discharge at its max rate, not more.
That part makes sense. I wasn’t sure if there’s a safety issue pulling more than intended/allowed or is it just not going to give any more current.
Only safety issue regarding batteries are specific to certain models, such as the TS10, which has reports of LEDs burning when using turbo too much using a H10 which can discharge at 10A.
Ahh so it’s an issue to other parts and not the battery itself? I was afraid of having a bomb.
For the Thrunite TC15 v3, am I ok to use the 35e is that not going to get the best if I turbo for awhile?
We should note that this is only true for “protected” cells. Unprotected cells can have huge amounts of current drawn from them (during a short-circuit for example), possibly leading to a cell fire and/or rupture.
Are you saying that if I put a Panasonic NCR18650B (rated at 4.9A maximum continuous current) in one of my triple 519As with a FET driver and bypassed springs that it will draw as much current as a Samsung 30Q (rated at 15A maximum continuous current)?
It might, but at a lower voltage certainly. It depends on if/when the light”s low voltage cutoff is reached.
That’s an external device limitation though.
I’m saying that the cell can have a lot more drawn from it than its datasheet max current rating but whatever is drawing the current must be capable of drawing that additional current and not shut off.
I’ve often wanted to see a test for that scenario since I’ve heard others say that the battery will only supply up to what it’s rated for. I just don’t have a clamp meter to perform the test myself.
I’ve literally tested at least a couple thousand cells at beyond their rating, over 350 different models of cells. They heat up more, their voltage-under-load is lower. But they can all do it if not limited by a protection circuit on the cell (or by the device).
A cell’s rating isn’t a wall where current is somehow limited to a constant-current value no matter how hard a device tries to draw current. The rating is just a number the manufacturer has chosen to give the desired number of cycles with the desired performance (voltage sag) at the desired level of safety.
The rating can easily be higher or lower depending on the criteria the manufacturer uses when setting it.
When picking the right battery I assume as long as you’re at the max rated amp or lower, you’re fine? I’m asking since I’m looking at a light with turbo at 9.8 A but the manufacturer rating is 10 A for continuous load. I assume I don’t need much overhead since turbo isn’t that long and that’s good enough for the cell?
Yes thats true for fault cases like a short circuit. But in normal cases, AFAIK, even if the battery is unprotected, most lights have LVP, so the driver will cut off power before voltage gets low enough to pull more amps than the max rated amount.
Yes 10A should be good enough. Unless you want the absolute max performance out of your flashlight because things like voltage sag of the battery plays some role during turbo. That’s why I read reviews of the cells before buying.
Best source for cell reviews - Mooch
In terms of safety, yes, you’re correct.
A 10A-rated cell being run at 9.8A is being run pretty hard though so there will be a decent amount of voltage sag and shorter run time. For some cells that can actually result in less run time than if using a lower capacity cell with a higher current rating that will run more efficiently at 9.8A. You’d have to check the results of testing to find the best cells for that size and current draw.
The low voltage cutoff will eventually kick in but we can easily pull 15A or even 20A from a 10A-rated cell (if the light can draw that much) until the voltage falls far enough. The cutoff will typically prevent heating past the cell’s max temp spec (often 70°C-80°C) though since the cell won’t be running for a long time.
Got it. I see that the cell I’m looking at NCR18650GA, is not on mooch’s guide.This is what I see below from the Parametrek guide. I guess I should be safe and get the Molicel P28B since it seems to handle better from the e-scores on 10A or P28A which is a bit lower for 10A but also rated/tested for 15A? I assume that’s how you should read this chart?
The P28A is perfectly fine for 10A, you wont notice any difference with a P28B. The difference in score is marginal, but yes P28B is a better cell overall. I suggest you get the Samsung 30Q for your 10A light. It can handle 10A well and you will get a bit more capacity than the P28. I use molicels only in triple or quad led setups.
