Fenix TK20 Max Voltage?

I have a TK20 dropped off last night and requested if I can increase its output. I took a look at it and boy is the beam gorgeous for an XR-E emitter. It's a neutral tint with a really tight hotspot.

I suggested that I make an 18650 body for it instead of trying to pry the emitter out.

My question is how much input voltage is allowable in this light? is it capable of accepting a single 18650 cell? 4.2v +-0.05v?

I doubt the max voltage would be 4.2, the TK20 was designed to work with 2xAA. I guess the max voltage would be 3.4 at best.

Labrador72 said:

I doubt the max voltage would be 4.2, the TK20 was designed to work with 2xAA. I guess the max voltage would be 3.4 at best.

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I was thinking of this as well but IIRC, when fenix first came out, their lights were very flexible with different types of power sources. Hopefully someone has a definitive answer for this.

No one else knows? I hope Fenix has information about this light after so many years ago.

Tiresius said:

No one else knows? I hope Fenix has information about this light after so many years ago.

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TK20 is supposed to work less than 3.2v

I guess it's time for an overhaul. Whole new 18650 body with an XP-G2 emitter for this customer that dropped it off.

It's a shame that the customer wants the emitter swapped. My personal feelings are that no other LED has come close to the tint on a properly focused XR-E Q2 5A. It's a spitting image of incandescent light and has a broad fan base around here.

From the sounds of it, the OP is planning on committing a crime.


Someone needs to call the cops, a priceless work of art is about to be destroyed!

That's what I suggested to him. I wanted to keep the stock emitter and just get him a better battery capacity. His complaint was that the light lasted too short and was not bright enough.

The custom body tube does not mean I'm going to destroy his stock one. I don't think the stock body can handle the 18650 bore because the o-ring pathway will be in the way and will possibly rip out. Hence, a whole new tube will be made out of 6061 aluminum. The emitter I suggested would be an XP-G2 90+ CRI on 1.7a AMC driver. I'm going to give him a quote and hopefully he does opt out because the cost for a new tube is pricy--especially for something that uses two separate pitch.

SACRILEGE! The TK20 is a collector's piece! The best neutral thrower I have with it's underrated low mode thar runs for like 10 hours. I would suggest you simply exchage his light for something else, as you probably could get near the original price for this gem.

Now, to answer your question about input voltage, I believe the 3.2 volt quoted by xlight is right on the money. Lithium AA's were not even on the market back then AFAIK.

Cataract said:

SACRILEGE! The TK20 is a collector's piece!

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Of course it's a collector's piece. The emitter at the time was unrivaled due to its throw AND gorgeous tint and beam. The amazing thing with this light is that Fenix managed to achieve this WITH an SMO reflector. That's something hard to come by because there's always the infamous Cree ring from XR-E emitters--even from many OP reflectors as well. The switch has a firm press and feels quite reliable.

Several hours ago, I called the gentleman and asked if we can keep the original emitter and up the driver to accept an 18650. He still refused to keep the head unit stock...I'd love for him to sell this to me OR trade for one of my custom Solarforce lights but he sees the potential in this light once upgraded.

IF he does take a trade-in, I'll just upgrade the driver to 1.4a and make a custom 18650 body for it. Keep the head unit stock because I can't ruin such a light.

I'll keep everyone posted when the day comes.

Bought a TK20 ~'08 or '09 4 or 5 years before I became a flashohaulic. I got the grey grip and a year or so ago I found the yellow grip on sale at the Fenix Store. I have used the light quite a bit and the color and beam is indeed nice. I didn't know it was a collector's piece. It is in mint condition, box, all accessories, both grip colors and not for sale. It is the oldest good light in my collection and one of the first my friends pick up. Nice to know people still find it still good after all these years.

I still LOVE my TK20, it's my first flashlight that got me hooked. Fenix should really consider doing another one, one that still keeps the 2AA neutral thrower tradition