charging 18350 in flashlight that uses 18650s, etc

RAH

Newly Enlightened
Joined
Oct 13, 2002
Messages
56
Location
New Hampshire
Hi folks. I haven't been on this forum for several years, but I am back with a semi-stupid question concerning charging batteries in flashlights, especially batteries that are not the regular size for that flashlight.

Specifically, Wurkkos (and Sofirn) flashlights often have interchangeable tubes that allow the use of an 18350 battery in a flashlight that is normally an 18650 (or vice/versa - an 18350 fl that can have a long tube attached to accommodate an 18650). These flashlights allow charging in the fl itself and I'm wondering if it is safe to charge say an 18350 battery in a fl that was sold as an 18650.

For example, can I charge my Wurkkos FC12 (an 18650 fl) fitted with a short tube (from Wurkkos) that fits an 18350 battery? The worry for me is that the charging circuitry in the fl might be too strong for the battery. (I assume going the other way - starting with an 18350 fl and adding a long tube with an 18650 - is OK and would just be slower than normal).

Even more questionable, so I'll ask - the Wurkkos WK40 (the multi-color fl) normally takes a 21700 battery, but it comes with a short tube that Wurkkos says can be used with an 18350 battery (I tried it - it works). But could you then charge that 18350 in the fl? There you are using a charging arrangement normally intended for a much larger battery (the 21700).

I obviously don't know much about charging and how the electrical components work. I don't mind using an external charger, but just want to know if the internal chargers are fully compatible with the batteries that fit in the flashlights. I just don't want to burn my house down!
 

Monocrom

Flashaholic
Joined
Aug 27, 2006
Messages
19,540
Location
NYC
Sofrin, Convoy, Wurrkos.... Check AliExpress and get you a good, cheap, basic charger. I mean, playing around with these types of cells when it comes to charging is just overall a bad idea. My Convoy M1 came with a good basic charger. My $16.oo Wurrkos TS10 with its beyond ridiculous user-interface came with all the accessories, charging cable, lithium battery, and the most basic charger I've ever seen. But the charger works great! Clearly designed for AA or AAA rechargeable lithiums only. Downright tiny, very portable. $16.oo for all that (free shipping too).

When there are such pragmatic and dirt cheap options out there for charging up such batteries, why take unnecessary chances?
 

Poppy

Flashaholic
Joined
Dec 20, 2012
Messages
8,311
Location
Northern New Jersey
The chargers cut off at voltage, not mAh so yes you are safe using the in the flashlight charge monitor. It doesn't matter the size of the battery, just the chemistry. You don't need to buy a separate dedicated charger like monochrome suggests, you can use the in light charging of the flashlight like @bigburly912 and @alpg88 mentioned. I agree with them.
 

RAH

Newly Enlightened
Joined
Oct 13, 2002
Messages
56
Location
New Hampshire
Thanks for your helpful replies, folks! @Monocrom , I agree that it might be safer using an external charger (although from the other replies, it sounds very safe in the flashlight too), so to be absolutely safe, I can do that. But I did want to know about the in-flashlight opinions. :)
 

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