(Fenix TK11) Non-Rechargeable substitute for "18650 Li-ion"?

[The Beacon]

Hi all!

I still can't seem to choose my first flashlight! After looking at the Fenix TK11, I see that the 18650 Li-ion battery gives better runtime than 2x CR123A batteries in the same application. I don't want rechargeable Lithiums, mostly because I would have to shell out for a charger. I was wondering if there is a Primary (non-rechargeable) Lithium battery that I could use to get the extended runtimes?

Is 18650 the size of the battery? I couldn't find anything that matched.


Thanks again for the help! :twothumbs

 

[Marduke]

You do realize that by the time you "shell out" for a charger and a couple cells, just a handful of uses and they have paid for themselves, right?

Rechargeable setups are HUNDREDS of times cheaper than running primaries.

 

[VidPro]

the 2x123s are a good choice, the extra runtime from the 18650 is partly due to the drive current with that voltage, so the brightness also could be concidered (even though it really isnt that big of deal).
there wouldn't be that much more juice in a (non-existing) primary 18650 than the highly used 2x123, its all about the market. the li-ion 18650 is a good item because its USED all over the place, in primary (throwaway) the 123s are used a lot.

so those are the choices, and the best choices in a real sence. even if there was some off-market hard to get 18650 3.6v primary which isnt very likely because of chemistry can sorta determine the best voltage, and a 3.0v single cell would not be so great either.

 

[The Beacon]

Yeah, I know that the charger would pay for itself eventually. It's just that I plan to use my torch infrequently and for short periods of time. So I'm more interested in a battery that will hold its charge over time. I read on wikipedia that Lithium-ion (rechargeables) deteriorate over time even if they are not used/charged frequently.

http://en.wikipedia.org/wiki/Lithium-ion_battery#Shelf_life

 

[Marduke]

So just use CR123's then.

 

[VidPro]

yup Use it or lose it. self dying batteries we have had some here that lasted more than 8 years, but they are finnaly giving out.

if you only gonna get 2 discharges a year, its not really worth it, EXCEPT for the idea that you can keep topping them off, instead of having ones you dont know how long they will go.

 

[The Beacon]

So just use CR123's then.

hehe, well I want the increased voltage/mAh that lithium provides!

 

[Marduke]

hehe, well I want the increased voltage/mAh that lithium provides!

CR123's are lithium....

 

[The Beacon]

CR123's are lithium....

oops! You are right! hmmmmm. Then I don't understand why this 18650 battery is giving better performance than the CR123As.

 

[VidPro]

there is like 3-4Watt thingies in each leetel 123 x2 that is 6-8Watts of total power

the 18650 has 3.6v X ~2200 so the total wattage is almost the same at about 8W, depending on the amperage draws.

but the 2x123 are 6+V , and the SINGLE 18650 is about 3.6v max 4v under a load , so depending on the driver and how efficient it is, and if it goes into DIRECT DRIVE, which most of them do.

so the runtime will often be much longer with the lower voltage, and depending on the curcuit, it could be much higher efficency when its IN direct drive

you really need to look at the CHARTS that show the runtime ALONG with the output level, in lumens or something, as that gives the best picture.

no doubt the 18650s have a load of power and are rechargable but if your seeing huge runtime differences its is usually because the lower voltage battery went DD it went into DD with a lot of its capacity left, and ran lower power output during a lot of its time.

 

[concept0]

Even though Li-ion batteries have slightly less energy density (energy per amount of volume) than lithium primaries, the volume of an 18650 rechargable is much higher than that of two CR123 primaries. That's why it has higher runtime than two CR123.

There is no 18650 primary battery. Even if there was, it would not provide enough voltage for the TK11, which is optimized for 3.7v-6.0v input. CR123 batteries only provide 3.0v.

 

[mdocod]

Even though Li-ion batteries have slightly less energy density (energy per amount of volume) than lithium primaries, the volume of an 18650 rechargable is much higher than that of two CR123 primaries. That's why it has higher runtime than two CR123.

As VidPro said and is correct, an 18650 and a pair of CR123s contain almost the same amount of energy. In fact, a pair of good quality CR123s has more stored energy than an 18650 when the 2 are compared at the low drain rates typically associated with single die LED lights. The TK11 is not regulated on an 18650 and therefor runs with steadily diminishing output to ~50% of initial output over the extended run, on CR123s, it runs at 100% output though almost the entire discharge. Lower output modes in multi-mode lights have more runtime because they use less power, and an 18650 has more runtime because it is forcing the light to operate at a lower output.

-Eric

 

[Bullzeyebill]

Welcome to CPF. Go to the Flashlight Electonics, Batteries included forum here in CPF and go to the sticky Threads of Interest and go down the list and pick info out from the 123 Battery Shootout, and the LiIon Battery Shootout. Look at other threads there too. The best info we can give you here is direction to more info. Please do research and you will have fewer questions.

Bill