How much spare capacity amperage should a battery have over the current draw?

LED Flashlights – General Info
1

So I’m looking at some new Convoys with the SST40 emitters. Specifically….
C8+ with listed current draw of 5000mA
M21A with listed current draw of 6000mA

I mostly have Panasonic NCR18650B with a max continuous draw rating of 6.8A (per liionwholesale) and they go on to say those cells are “happiest at 1A - 2A of draw”. So as these newer very high powered Luminous-powered lights are hitting the market (and I’m finally expanding into 21700) I’ve decided to order new batteries that are up to the task. So that begs the question…how much reserve current headroom should the battery have over the max draw from the flashlight to protect the cells for longest possible lifespan?

Example, in 21700 batteries The Samsung 50E is rated for 9.8A drain and the M21A flashlight will provide a 6A load. Would I instead be better off buying Samsung 40T cell with a much higher 30A drain rating? I’d rather have the 50E cell because of its greater 5000mAh capacity (20% more than the 4000mAh from the 40T battery) but I don’t want to cook the batteries.

Similarly in 18650 cells, I’m considering the 10A (max) drain Panasonic NCR18650GA cell because of its big 3500mAh reserve, but its going to be looking at a 5A load from the SST40 C8+. I’m wondering if I should accept the tradeoff to a lower capacity 3000mAh battery such as the LG HG2 with a substantially higher max drain rating of 20A or the Murata VCT6 with a “15-30A” max drain rating.

What say ye?
2

The 50E and NCR18650GA are great bets from these lights, no worries.

Also, choose the 5000k options of the lights if possible.

3

Definitely 5000K, not even a question. :wink:

4

Frankly, by the time you’d notice any “performance loss” in a cell, you’d be old and gray.

I still burn up old laptop pulls in low-stress lights, and they work fine. Unless you got a screaming hotrod of a light that pulls 20A or more, you’d be good even with most generic cells.

I’m fine with the supplied Sofirn 21700s in my C8Fs and the like. Sure, I might be able to squeak some higher numbers with a low-cap high-drain cell, but the Real World™ difference would probably be imperceptible. You’d probably gain more light output by making sure the front glass was free of dust and fingerprints.

5

The current draw depends on the battery type,
you can’t calculate with 6A Convoy rating and expect a 18650B with 6.8A rated to deliver 6A

the lower the internal resistance is the more current the battery delivers with same charge level