Using 18650/17670/16650 VS 16340 X2

Batteries and Chargers Rechargeable Batteries
1

I am starting to use more rechargable Li-Ion batteries for my new found flashlight interests.
There are a few questions I like to straighten out, if any one can help offer some insight.

The higher the rated amperage (capacity) the battery can last longer, but will it push out more current?
For 18650, the limiting factor is the ability to charge beyond 4.2V for those newer high cap >3000mAh for it to attain maximum potential, otherwise a lower capacity battery is preferred because of less cost? or ?

Many lights cannot fit 18650 due to ID (unless bored), therefore the ‘thinner’ options like 17670 & 16650 exist.
However 17670 & 16650 is far less capacity compared to 18650.

The main concern for protected cells are for their longer size not fitting into chargers properly, but in a flashlights this is easier to solve due to the spring.
What will be a perfect charger then? Would you say it is the Nitecore i4 v2? I dont think this i4 charges beyond 4.2V though…

*How about using 16340 X2 , wouldn’t 2 cells give a higher voltage (7.2V) than just 1 18650 (3.7V)? Therefore the lights run much brighter?
Can I assume 16340 X2 draws more current, which is an amazing benefit!
My thinking is given less run time (lower capacity) of 16340 in exchange for a higher voltage and current, thus a brighter light.
Therefore going 18650/17670/16650 X1 defeats my purpose of having a strong and powerful beam.
(In my applications, I like the light super bright (max) for about 80 minutes. Recharging afterwards is ideal for me.)

How about using 2 CR123 primaries? I heard CR123 x2 is still the best brightest option that exist, True? Why?

2

Compare the total mAh of two good 16340s vs. a good 18650. The little ones don't even come close. All the development is being applied to the bigger cells, as they're so common in laptops & automotive apps, nothing much of that tech is being put into the 16340s. Maybe one day we'll have 1800mAh 16340s but by then either 18650s will be at 4800-5200mAh, or will have been phased out for another format cell altogether.

If you have a true regulated driver that's designed for say 2.8v to 8.4v, you won't get any extra light from the extra voltage. If it's direct drive on high, it WILL get brighter... 2x cr123s will usually sag enough that the LED isn't fried, but 2x 16340s in direct drive is another story. Don't try that setup with one of those DD drivers unless you have some spares on hand to fix it when it pops.

3

Hi CC, Thanks for your input, I understand the regulated driver won’t give more light, but the extra voltage will make it go running longer.
On the other hand, if the LED is direct drive (meaning 1 single voltage input??) and can handle 16340 X2 (7.2V) the light will actually be brighter than 18650 X1?

In regards to the common P60 dropins, I don’t see any P60 dropin in DD with 7.2V around, or am I missing something?

4

Well, direct drive usually isn't a selling point since that, usually, indicates a cheap driver that would be 'too expensive' if it were built to actually regulate anything. DD means that whatever voltage is in the cells will be applied straight to the LED. And if the voltage doesn't sag under load down to something the LED can tolerate, the LED will go POOF. And then you will have to go shopping for a new emitter and a driver that won't fry things... that, or learn the lesson that you can't put 8 volts to a ~3 volt LED and have it work longer than about half a second.

5

The best 16340s contain about 700mAh. Two of them would be 1400mAh then. Most 18650s contain a lot more, some have more than twice the capacity of that.

But there are some dropins (oveready for example) that will only be regulated when run on two cells. But you get a lot less runtime..

I prefer 18650s. 16650s are also good, smaller/shorter lights should be able to run on 18500s or at least 14500s.

There is one good reason for that: besides from 18650s which are industry standard the 3 smaller form factors are produced by well known companies such as Sanyo, Panasonic, Sony.. all the other sizes are not. They are probably just some crap chinese cells.

6

This is sort of complicated. But I’m not very clever and sort of understand it, so it can’t be that bad.

mAh capacity is basically how long the battery will last. The more the better, like a bigger fuel tank on a car.

Voltage is how much kick the battery has. I guess a little like bhp in a car to keep to automotive analogy going.

Without regulation, so direct drive either an Incan bulb or an LED the higher the voltage the brighter. But the more mAH the longer it’ll stay lit.

You can direct drive LED’s, but 2x li-ion will generally be too much voltage for most and they will blow. Although some Incan bulbs could work very well setup like this.

A combination of voltage and mAH will give you a watt hour rating. Using electronic drivers you can either take a high voltage and reduce the voltage making it to the led and use some of this excess power to increase runtime. You can also take a low voltage high mAH battery and by a different type of driver make more output voltage at the expense of burning more mAh more quickly.

In my experience most drivers are optimised to do one or the other. Which is why so many can only use specific voltage ranges. Some drivers have the ability to act as buck or a boost driver so can accept a wider range of voltage inputs. But often they seem less able to perform as well on all types.

For example I have a Crelant V9CS. On an 18650 it runs without regulation. This is fine and it actually runs very well with looong run times. You can however run it on 2x16340 (or 18350’s). Much lower mAh but double the voltage. In this guise it is brighter and can maintain this brightness for almost its entire runtime. But the runtime is quite a bit less.

I have some other lights that exhibit similar behaviour. Basically a single li-ion will say too much and the light will dim, despite a claim of being regulated.

On the flip side I have two premium lights (Klarus and Eagletac). These are both 2xCR123a lights. But I run them on an 18650 and a 16650. They both exhibit identical performance when used on one battery instead of two. I think this partly because they are higher quality lights and maybe because they are t being driven as hard.

16650’s are fine tbh. Lower capacity yes, but run time is still good and unless you are doing something very specific where every minute extra counts I don’t really have a problem with say 5-10 mins less runtime.

7

Its more. 16650 pack around 2000mAh, good 18650 are >3000mAh. But they are a great option for lights that normally run on two CR123 if you dont want to bore the battery tube.