Best performance cell 18650 available for my light?

[ateupwithgolf]

https://www.banggood.com/Astrolux-M...arching-Light-p-1712104.html?cur_warehouse=CN

I've read some on here about which cells to use, but then just get more confused. Regardless of cost, what is the best cells for max performance (not necessarily run time because they are typically shorter bursts) can I purchase and why? I don't know what I'm looking for tbh.

I don't know the benefits/drawbacks of say sony vtc5a, d, vtc6, samsung 30q, etc. I assume I'll use unprotected cells. The review I watched recommended 30Q, but why? Btw, I'll be using the short body with only 4 cells. Thank you.

 

[adamlau]

The Astrolux MF02S V2 SBT90.2 will draw up to 20A. For max burst performance without regard to runtime: Samsung 20S and the Molicel P26A. 30Q offers more of a balance between performance and runtime.

 

[john61ct]

There is no one "best".

Do the basic legwork for our use case.

what is your desired amps discharge desired per cell?

The higher the C-rate the shorter the runtime of course.

Batteries designed for the highest C-rates will store fewer mAh

and have a shorter lifespan, thus a higher cost per year needing more frequent replacement.

Thus it is better to buy high energy batteries rather than high power ones, unless the latter is strictly necessary.

 

[peter yetman]

A high current cell is less likely to heat up during use at regular discharge rates than a low current cell. Thus its life will be longer not shorter.
P

 

[john61ct]

Sorry I was not more clear. Yes actual tested cycle longevity at a given C-rate is independent of whether high power vs high energy density.

IMO stupid to pay extra money for the higher-C rate cells and sacrifice energy density as well

unless a high-C rate use case truly requires them.

It is the high C-rate **usage** that drastically shortens lifespan, no matter the cells, relative to a gentler use case.

There is no "regular" C-rate, the number needs to be specified for objective discussion.

 

[Chicken Drumstick]

I'd vote Samsung 30Q. They work really well in all of my lights. 3000mAh and pretty decent amp draw. Been running them for years, never needed to replace a single one. Samsung 25R very too, in theory capable of higher amps than the 30Q, although most of my lights show very similar results. Have been running a load of these for even longer than the 30Q's. Never needed to replace one yet, despite lots of use and charges.

 

[richbuff]

Max capacity versus max peak discharge. Choose most runtime and less peak performance, or choose less runtime and more peak performance.

Or medium amount of both.

More capacity = more runtime = less peak discharge performance.

Less capacity = more peak performance = less runtime.

The biggest bathtub has the smallest drain. The smallest bathtub has the biggest drain. The medium size bathtub has a medium size drain.

Pick such and such cells for max runtime, or pick the other cells for max peak performance.

 

[john61ct]

30Q have been shown to self-discharge crazy fast.

Also inconsistency issues, but that is really only critical in building large packs, e.g. for eBikes.

LG HG2 and VTC6 are much better in that category

Also Samsung 50E for high energy density, great longevity

their 40T shorter cycle lifespan but great for supporting high C-rate bursts

 

[caelyx]

The biggest bathtub has the smallest drain. The smallest bathtub has the biggest drain. The medium size bathtub has a medium size drain.

This is a useful metaphor for explaining it; thanks!

 

[Chicken Drumstick]

30Q have been shown to self-discharge crazy fast.

Also inconsistency issues, but that is really only critical in building large packs, e.g. for eBikes.

LG HG2 and VTC6 are much better in that category

Also Samsung 50E for high energy density, great longevity

their 40T shorter cycle lifespan but great for supporting high C-rate bursts

Can't say I've noticed self discharge issues at all. Do you have any reference material for this?

40T is a 21700, not much use for an 18650 light

 

[Chicken Drumstick]

More capacity = more runtime = less peak discharge performance.

Less capacity = more peak performance = less runtime.

That isn't always the case. Drive a high capacity battery hard and you'll likely get less runtime vs a lower capacity high performance cell. This is because you'll get more voltage sag from the high capacity one.

If you use low and moonlight modes mostly. High capacity is the way to go. But if you use High and Turbo modes more often, you'll probably get better runtimes on a lower capacity high drain cell.

 

[ateupwithgolf]

Thank you for the replies, I'm getting educated. So a Samsung 30Q and Sony VTC6 are exactly same specs, 15A, 3000mah. Both recommended it appears. Shop on cost I suppose? If my light draws up to 20A, then wouldn't I want a cell that is rated for 20A to reach its capability? The Sony VTC5D is 25A and 2800mah, that seems to me a decent balance if you disregard cost?

 

[adamlau]

"The VTC6 starts out as the better performer, by a little, and might be the better choice if you aren't using your batteries hard. The 30Q, while not performing quite as well as the VTC6 at the start, would be the better choice if you habitually abuse your batteries, i.e., discharge and charge them hard." - Mooch via Bench Test Results: Which lasts longer? VTC6, 30Q, or HG2?

 

[john61ct]

Nope the VTC6 is by far the better choice.

I'd only settle for 30Q if it were say 30% cheaper delivered.

 

[john61ct]

If my light draws up to 20A, then wouldn't I want a cell that is rated for 20A to reach its capability?

Manufacturer current ratings cannot be relied on comparing between different makers.

7C is very high, but I believe you said only in bursts?

3-4C continuous should be fine, likely to get at least a few hundred cycles

especially if you stop drawing before the battery rests at 3.3-3.5V

 

[peter yetman]

I was just going to say the same thing.
We don't seem to have mentioned HKJ's site which, if you're serious about getting reliable cells, is essential reading.
https://lygte-info.dk/info/indexBatteriesAndChargers UK.html
Not the instant gratification of posting here, but much more useful.
P

 

[seery]

Samsung 30Q

 

[Chicken Drumstick]

Thank you for the replies, I'm getting educated. So a Samsung 30Q and Sony VTC6 are exactly same specs, 15A, 3000mah. Both recommended it appears. Shop on cost I suppose? If my light draws up to 20A, then wouldn't I want a cell that is rated for 20A to reach its capability? The Sony VTC5D is 25A and 2800mah, that seems to me a decent balance if you disregard cost?

Nothing wrong with the Sony cell. I don't have any, but never had any issues with the Samsungs and they have typically been easier to buy for me in the UK.

As for the MF02S - it uses 4 x 18650 I believe. So the load will be split across the batteries. Pretty much any IMR will work great in it.

 

[Chicken Drumstick]

Nope the VTC6 is by far the better choice.

I'd only settle for 30Q if it were say 30% cheaper delivered.

Far better...

Do you get a light meter out every time you turn your flashlight on and record total On time too?

Chances nobody would be able to tell the difference by eye.

 

[WalkIntoTheLight]

"The VTC6 starts out as the better performer, by a little, and might be the better choice if you aren't using your batteries hard. The 30Q, while not performing quite as well as the VTC6 at the start, would be the better choice if you habitually abuse your batteries, i.e., discharge and charge them hard." - Mooch via Bench Test Results: Which lasts longer? VTC6, 30Q, or HG2?

Wow, that's some heavy use, especially with a 4A charge. But 15A discharge is pretty common on high performance lights like an Emisar.

Only 50 cycles, though. The 30Q is rated for 250 cycles to 60% capacity, whereas the VTC6 is rated at 500 cycles to 60%. It's surprising the 30Q holds up better, at least for 50 cycles. It would be interesting if Mooch extended the test, to see when each battery finally gives up. On paper, the 30Q should give up before the VTC6.