Help me understand 18350 batteries

So I found out that I can get short tubes for a lot of my 18650 and 21700 lights, and use 18350 batteries to make the lights smaller. For example, Wurkkos FC11 and TS21. For the ones that I mostly use in low mode, that’s great. But help me understand the charge and discharge situation.

This from Wurkkos for example:

Standard charge = 170mA
Rapid Discharge = 400mA
Max Discharge = 4200mA

If I accidentally use turbo on a TS21 that consumes 6A, what will happen to the 18350 battery? Am I responsible for not turning on Turbo if I’m using a 18350 battery? Or else ka-boom?

And how do people charge at such low currents? 170mA? My external charger has a 500mA or a 1000mA selector. What chargers allow you to slow charge to that extent? If I find a very weak USB charger, can I use that in combination with the light’s built-in charging capability? Basically, I’m using a low current USB charger to limit the charge current going through the USB-C port to the flashlight?

Or is that not really what people do? Do they just use the short tubes for CR123A batteries, and not really use rechargeable 18350 because it gets dangerous?

1 Thank

The battery won’t explode, but it’s lifetime will be shortened (perhaps dramatically). Also the brightness will be lower that with “full size” batteries.

Don’t use internal charging. It’s current is too high. A weaker power supply won’t work. You need an external charger with low enough current. 250 and 500 mA are commonly available.

I don’t really get the appeal of 18350 or 18500. The light doesn’t get smaller. Only shorter. Which with most compact 18650 lights doesn’t actually make it easier to carry. Sometimes it makes them worse as they become more of a boxy shape in your pocket.

But the biggest thing is runtimes are so heavily reduced. Typically to probably 1/4 of the runtime with a good 18650. Which sort of defeats the object of light in this class. A 14500 or 16340 light will offer similar runtime but be slimmer and more ergonomic in your pocket.

18350 won’t handle high output as well. If they can’t supply the amps then output will suffer. Sometimes by a lot. But in such situations you’ll be pushing the battery harder too. Which is more heat even worse runtimes and will likely reduce the life of the battery.

But sometimes you need to try these things for yourself to see how you get on with them. But for me personally. I don’t run any lights in this configuration.

I think I get what you’re saying. But all those things aren’t too important for my use case for bedside light. I mostly use it in moonlight mode, and occasionally in medium or high, so low output is absolutely not an issue. It goes into my pajama pocket, so even slightly smaller and slightly lighter is nice. Run times aren’t that important, it’s not on hours at a time, and I can recharge it with my phone charger for half an hour every few months.

The most important things - low moonlight, Anduril UI, indicator light, onboard USB charging - don’t all exist in any 14500 or 16340 light.

I’m hearing that I shouldn’t be using the onboard charger though, so that could shoot down my plans.

Thanks. You might’ve just pointed out something I’ve been doing wrong with my normal 18650’s. My external charger regularly charges them at 1A. I think I need to study up on chargers.

For 18650 the internal charging is fine. Most high capacity or high drain 18650 can be charged with 1.5 A or even little bit more.

Oh, that’s a great find. Thanks! Might be another light to feed the addiction :slight_smile:

i agree about 18350

16340 usually has about the same energy and power, and the lights are much smaller

sc21 pro sofirn

also, using CR123As is even worse than 18350

the light will think it is running li-ion and cut off way before the battery is empty

wle

“basically, if the battery is charged at the same rate as the capacity, then it takes 1 hour to fill the battery. This is considered a “fast” charge, and is called 1C”

not really

it would take .8 hours to fill to 80% of capacity—usually that is where it has to switch to constant voltage/tapering current mode
or the volts would go over 4.20

the other 20% of capacity might take another 4-5 hours

and adding that final 20% every time, will reduce cell life somewhat

wle

I’ve been using a Xtar PB2S as my external charger and using a small USB charger as a current limiter. Do you have any recommendations for chargers that will let me select a lower charge current as well as limit the max charge to the cell? I wish my charger would just stop at 4.0V instead of going above that.

me? no i just have a plainish one that goes down to 300mA

wle

You sure about that JS? I always thought a charge rate of half the rated capacity was referred to as ‘.5C’. ICBW (and in fact am on a regualr basis).

No worries JS. Perhaps you’ll help me fix one of mine sometime:-)

Also be careful about constant discharge rates…

SkyRC MC3000 set for 1A discharge with 50mA reduce… seems it wasn’t fast enough

Vapcell 14500 L10 vs Wurkkos 14500

Nothing terrible will happen. The cell will just not be able to deliver so much current, so your flashlight will not achieve max brightness. That’s all.

Just buy a higher quality 18350 that can deliver more current, for example:

You can get 18350 with 1100 mAh capacity vs about 850 mAh for 16340, so that’s about 30% more.

The 850 mAh battery capacity listed in the spec sheet would be enough to convince me not to use them. When I first started out I was using the cheap batteries and found the capacity was rarely what was on the label. They work great if you don’t care about run times or switching out batteries. Now I stick to buying NCR/Panasonic 3,400 mAh batteries. They are a little more expensive but honestly rated, giving me the maximum time between recharges.

[quote=river345]

sofirn sc21 pro has all that, low goes down to 1 lumen maybe
it is also cheap ish
16340 800mah is what it comes with

wle

[quote=jon_slider]

:person_facepalming: read the link

//// i see it ……
it;s wrong for li-ion——

Wurkkos TS10 is a bit smaller and lighter than the previously recommended Sofirn SC21 Pro, takes a 14500 battery, and runs Anduril 2. What more could you want? Currently on sale til maybe tomorrow, see this post