advice for 18650 battery on Sofirn SP31 V2.0


I am looking for a 18650 battery with USB-C port included on it (I do not like the idea of having an external charger which can be lost) to go on my Sofirn SP31 V2.0 5I do have several of them). It seems that the SP31 v2.0 accepts both protected and unprotected batteries. Which one would you recommend, this type of battery seems quite scarce compared to normal rechargeable batteries ? I have found several types :

The nitecore are much more expensive, but the Liitokala seems to have a very bad reputation, so I think I will go with the nitecore.

Any suggestion ?

Yours sincerely


Don’t get a battery with built in charging.

Get an external charger and just put it somewhere you won’t lose it.

Hello Jeff

Thanks for your answer. What is the reason for preferring an external charger ? I imagine that an internal charger takes more space and reduces battery capacity and as such is more efficient or are there other reasons (reliability, safety…) ?

I will consider this option for myself, but in any case, I want to give one my SP31 flashlights to my cousin who is not a flashlightalcoolic and not very well organized, so for him at least I would prefer an internal charger on the battery so that he does not loose it… :slight_smile:

Yours sincerely


Not very well organized?
Whether he looses the charger or that little USB cable, makes no difference.
The charger will cost the same as the surcharge for the battery-with-charger.
And if he breaks (or looses) one, it will cost less to replace that item than an all-in-one-battery.

Hello Henk4U2

Thanks for your remark.

The difference is that with an USB cable cable you can charge both your phone and your flashlight. You will charge your phone everyday, your flashlight once in a while. When you are an occasionnal flashlight user, you are less likely to look for your USB cable than your flashlight charger when you need it.

When I do travel, I do always have an USB cable with me because I will need it anyway so it is worth carrying. I will not carry a battery charger because I may need to use it only once in a while and it is relatively cumbersome.

So I can agree that an integrated charger on a battery is less efficient ta-han an external one, but except if it appears there is safety, compatibility (problem of length for instance) or reliability problem, a battery with an integrated charger seems a good solution to me, at least for my usage, hence my question, which battery with integrated USB C charger is recommended for a Sofirn SP31V2 ?

Yours sincerely


You got it. Pretty much that.

Batteries get hot when charging, chargers get hot when charging. Put them both together in the smallest package we can…Not a brilliant idea. These aren’t devices made by Samsung or Apple. They do fail. And it’s not a 1 in a million longshot. It’s more like when and how, not if.

I have no recommendations for any batteries with a built in usb for you, I wouldn’t recommend any of them to anybody. Sorry.

I’d look for other solutions. Flashlights with onboard charging, more portable chargers. There are chargers that can run off a powerbank, there are powerbanks that are also chargers themselves. All in one. None of them are foolproof but it’s an improvement.

Thanks a lot for your analysis, pretty clear…

Yours sincerely


There is always the option of a second light with built in charging. I charge a battery in my sc18 then swap batteries with the sp31 and plug in the sc18 again…

That is an idea. But I did purchase in the end batteries with built in charging capability.