How many extension tubes can I use on one flashlight - like Yezl Y3?

Today I got my Yezl Y3 + two extension tubes (did only order one I’m sure of, but got two).
Tried to use all three, with three 26650 batteries, and it worked 100%.
How many tubes can you have on that light, and is there a limit per light? Lets say that I want three extension tubes on my Shadow JM35, can I do it?
Or will more batteries, make to much current and can damage the light?

Maybe a stupid question, but since I now got two extension tubes, I have to know if I can use both?
And if there is any reason to buy extension tubes to other flashlights, to make the runtime better.

You can add quite a few to the Y3, but more than 2 extra and you'll need to switch to something like NiMH C-cells or destroy it with too high voltage.

So two is OK to use, aka 3 26650 batteries at the time?

Yes, they're also sold in that configuration. With 5 extension tubes it you can use 8 C-cells, preferably Ni-MH. Do not try 6 Li-ion cells!

Always check the driver's input voltage specs before adding extensions.

If its the same spec as the original the light it will run from my memory on 1, 2 or 3 cells with low voltage protection working on any of these combinations.

tnx. Not that I will use 3 tubes very often, but it can come handy to get longer runtime if I need it some times.

I assume your aware that you should really only use three matched cells in series with protection circuits?

That's 2 tubes, just to be clear, for 3x 26650's. Probably what you meant but we don't want others reading this to possibly destroy their light by adding 3 extension tubes and running at 16.8V.

One tube is on the light + 2 extra tubes = 3 tubes. So you say that is a bad idea? It worked fine.
I used 3 x Trustfire 5000mAh protected batteries (they are tested, and they actually have 5000+mAh on it).
And to @MRsDNF, yes I have learned that if you are using more then one battery in a light, you have to use the same type.

3 batteries is fine but they should not only be the same brand, type and model but used also as a matched set from new.

I'm not sure you understand and with your track record we dont want anything to go wrong.

I have 16/pcs of protected TrustFire 5000mAh batteries, that is brand new, all is tested, they have around 5000+mAh, so they do match.
I also have 8 ShoShine batteries. I have 8 KeepPowers, I have 4 VapPowers. So if I use more then one, I use batteries from the same set. Is there more in to it? Since I don’t see batteries comes with 1 of 4, 2 of 4 etc on them. So when I have got 16 exact the same batteries, all tests around the same, of course, you are lucky if two batteries give you the same mAh number. But they are in range, lets say from 5000 - 5099mAh. They all from the same source/factory. When I buy 4 batteries from GB or BG, I do not know if they are from the same batch or something. But if the mAh range is the same, I think it’s safe to use them? Or do I have to call the factory to mark them in order so I know what battery to use together?

You should mark them yourself or keep them together in the same container. If one ages differently/more/charged less/more/has a capacity less/more, it can become dangerous to put it in series with other batteries. So buying 3 together, testing their capacities, then keeping them as a matched set is what you should do for series lights.

I just wanted to be abundantly clear that it didn't seem like 3 extension tubes added to the base single-cell flashlight. Remember, the general public reads the forum for information, too.

Ok, no we are talking two extra tubes to the tube on the flashlight (with 1 x 26650 battery ) so total 3 x 26650 batteries.

@b42: Good idea. tnx.

YW but you should read up on why…its possible for batteries to reverse charge and explode in unmatched sets. Lots of info here about it. Going 3x protected matched cells, testing batteries with DMM and/or testing charger is best to prevent this.

As to the first part, I’m not 100% certain you know yet either (maybe you do, but its worth going over for everyone reading), the ONLY reason you can add more extensions on that light and use it is because it was designed specifically that way: to be used with one, two or three batteries. MOST cannot do that, because they were not designed that way, and you will kill the light if you add batteries + extensions past whatever voltage it was designed for.

Matched voltage too! Test with DMM after charging and rested, is what I practice, helps me to judge performance if one is dropping or not charging like the rest, even if they are new and from the same batch, could be the charger, or a bad cell?

Hello! :-)

Quick question fellows, let's see if someone is wishing to provide an answer here: what's the thread size on these Y3 extension tubes? I am looking for an M31×1 (31mm male thread diameter, 1mm of thread pitch) extension tube, this one looks like that.


Any other substantially better deal for it than this one at FastTech?


Cheers ^:)