Xtar B20-U3 - What's Going On?

I have really been looking into torches for the last few weeks especially 18650 compatible torches and this Xtar B20-U3 has got me stumped. Almost all ~1000Lm Torches I've found using one or even more 18650's will burn at that 1000Lm for around an hour some coming close to two but this torch will go happily for three hours according to Xtar that seems very long to me especially for just one 18650!

Another 18650 torch I've been looking into is the Fenix TK35 an awesome looking torch, takes two 18650's and will burn at 900Lm for "only" 1 hour 45 minutes according to Fenix another torch I really like the look of the Fenix TK51 will take THREE 18650's and will again I say "only" burn for 3 hours 30 minutes at 900Lm pretty much the same time as the B20 will put out from one battery and 100Lm brighter..?

I'm obviously a complete noob to this stuff. Could someone explain to me how this torch can get so much from a single 18650? Does it use some new ultra powerful & efficient LED or is something else at work here? I did notice the lower lumen run times were a lot longer on other 18650 torches especially ones running multiple cells.

In case the above is too long: How can the B20 pull three hours at 1000Lm from a single 18650 when most dual or more cell torches at even less lumen (900) can barely reach two hours?

Maybe it uses PWM, or has a really quick step-down.

No light of that size can handle the heat been produced by the led, with such small heatsink.
Nowadays most lights have step-down. After 1/3 or 5 minutes the light enters a lower light level, to protect the light from over-heating.
The runtime shown than, is just 'what if it could handle the heat'.

The only CPF reviews I've read so far didn't include any time tests I was hoping they would. I also forgot to mention in OP that this is a $50 or less torch, I'm comparing it to $100+ torches there it's crazy. My friend is getting one soon which is how I heard about it so I suppose I'll be able to have a good look at it then.

I am kind of thinking that maybe those XM-L U3's are just that much better than the U2's but I know nothing about LED at all so I'm hoping someone here can tell me haha.

As said no single 18650 light will run at 1000lm without step down,iirc the b20 is not very well regulated.So depending on the light and what lumen it steps down to determines the manufacturers claims which are misleading.

I would say 500lm is still a big ask for 2hrs,it will be a warm light anyway..............

Short answer - they are lying. 1k lumens OTF is at least a 3.5a draw, so about an hour from the best 18650, assuming it can stand the heat, which it won't anyway. You can't get around physics.

Interesting thanks guys. I just noticed from a lot of the CPF reviews of Fenix torches the listed run times have not been far from the truth if not underrated in some examples.. This being when the reviewer bumps it back up to maximum every time it steps down until it no long will. So I started to think maybe torch brands try not to go too far from the truth when listing their results but I guess some still do! Shame I can't find a review where someone has timed the light while measuring the Lumen output and put it back up to max every time it steps down to see how long it really lasts.

Most manufacturers exaggerate.............marketing sells after all.

Fenix,i will use the tk75 as i have that :laughing: yes you can step back up after 20mins on turbo(2600lm version) or after 15mins (2900lm version)

If you want a light to sustain 1000lm+ for 2 hours(example)or so then it needs to be a multi cell light.One with a reasonable body/head size to help heat dissipation.

Also the tk61/tk75/tk76 for example have the options of extender kits(same kit will fit all 3 lights).So another kit or even 2 kits to double or more the running time and also less draw per cell, as spread over 8 or even 12 than "just" the 4 cells in standard form.

Haha, very true.

I am not really after a 1000lm torch that will run for two hours I was just kind of shocked by the B20 and noticed it had a new (read higher number haha) LED than most the torches I was looking at XM-L U3 rather than U2 so I was thinking, well maybe this is something that has just come out and soon Fenix and other brands will be releasing their own U3 supporting models and I should wait for that seeing as they're so much more efficient. But I'm glad that thought was wrong as I really want to order some new torches to use for my up coming camping trip haha.

Since joining these forums my list changes almost daily and it's hard for me to commit to actually buying haha. So the latest list consists of a PD35 for daily use and a TK75 for lighting up large areas/searching.. and reversing at night in the bush haha. Then I'm also pretty keen on the TK51 & TK35 but since getting into the TK75 I feel that maybe I won't need them so much. The only thing I've managed to order is the Lantern, the first thing I ever asked about on these forums before I caught the torch bug.

I love both my tk51 and tk75,the tk75vn is modded to 4400lm so not really fare :laughing:

However mods apart,if i had to pick then the tk75 is overall a more powerful light.The tk51 uses 3x18650,the tk75 4x18650.

Pros with tk51 is the 2 leds,1 throw,other flood and 16 variations to modes or just the use of either.
Pros of tk75,just a great all round light for throw and flood and options of extender kits if required.
The tk51 is still a substantial light



tk51 and tk75vn



Either you will like,if i had to pick the tk75 would win overall

Yes as I've said before I'm worried I'm just going to end up ordering all of them haha. That is fine over time but I need to be very selective with what I order now so I don't spend too much, I really like the TK51 for all the features you've told me about it, namely the iirc 18 different configurations you mentioned you could set it up in I like variety haha. But for now I think the TK75 has won for me also, I'll have the PD35 for the small/common stuff but if I need some serious light I can grab the TK75. I do think in time I will get myself a TK51 though but best to spread it out and go easier on the savings haha.

I really love the extender tubes and that they actually slightly more than double the run times it's great. Only problem is the extender kit with the four cells + shipping almost costs as much as the light itself haha but I think worth it. Especially if I upgrade over time.

Woops almost forgot. As always thank you for the excellent photography.

Welcome,but far from excellent :laughing: but gives an idea

Best idea is get the pd35 as you say for the small light,then the other for larger illumination.
I think your doing it right with tk75 1st,i dont know if you would take the tk51 out instead tbh ,i guess if you need smaller light(head only ) then its an easier carry.

Try banggood as sure worldwide free delivery and kit is around £19 or so delivered.

Instead of maybe the tk51,look at the tk61,this throws excellent and still has usable flood too and is a different beast to the tk75 and very different to the tk51.Not same lights obv,strictly speaking not too much in common BUT the tk51 and tk75 dont have huge differences out of the business end,both throw,both flood so i would look at a different purpose light(thats just me though).
tk61vn on right

Maybe worth pm vinh for delivery,you may even find it cheaper overall and a better light regarding performance and internal mods.............just a thought

Also regarding any light not only is his service 2nd to none,but in every other way too:thumbsup:

Haha, alright I will take a look at the TK61 but I'm pretty set on my PD35 & TK75 choice for the moment. Thanks again for the pictures, do you own every single Fenix torch!? Haha.

Also cheers for the BangGood suggestion I'll check it out. Also I was planning on staying away from mods as if I started including them in my choices things would get even more complicated but you've made a good point that with shipping to Aus Vinh could be a similar price and a I'd get a better torch.

Thanks!

Yes i dont mean get a tk61 instead of a tk75 as the tk75 is a better all round light if makes sense .......well imho it is.

I mean instead at a later date looking at the tk51 which serves a similar purpose to the tk75,the tk61 would make a nice addition as its a "thrower" but flood too.
Couple more pics,nope dont own all the fenix lights :laughing: but i admit i like the brand!!! nice light,well priced,well made,simple UI........whats not to like

Fenix lights i have

Shame no carry case(have the plastic case normally) so have a camo(think flask holder/pouch) on way,will post pics once i get it







Modded tk61vn at 1735 ANSI and 622kcd= amazing....note the flood too

This is zoomed in a bit,distance is only around 150m and misty conditions

reaches the moon...........honest :laughing:


Ok on a serious note,the bonus of the tk61 is the battery carrier is the same so can use in either or have a spare if take one light out,also the extender kits fit both(pattern a little different on tk61)

Dont quote me on this as i am going off my memory but possibly $35 to oz........obv varies on light size but sure around that.

Trouble is with vinhs mods,you will want a vn from them on...............its not trouble its good so if not ready maybe wait a little as it will probably make you just want his lights when it comes to the big boy lights :laughing:
His work is excellent,well better than that,just gets the best and some out of the lights,but more work than just cranking the A up,beefs up carrier etc too amongst many other things where manufacturers cut corners(thicker wires to better heat sinking like copper)

Good luck,either way you have great taste in lights,the tk75 is one of my fav lights as its just so good at everything

I see what you mean now.. It would be nice to have a good thrower and that TK61 looks like a laser! haha nice shots. I have mulled over the thought of getting a Vinh and I have decided I better just stick with Stock for now and leave the modded torches for future purchases, just to keep things simple for now but also because I really would like to have these torches before the 16th of April so I can have them for my trip. I will certainly hold your recommendations for Vinh in high regard though and go straight to him if I'm ever feeling game for a modded torch!

Also again thanks for the BangGood recommendation I had never heard of them and they stock both the PD35 and TK75 for a better price than what I was looking at before! So you've saved me some money there.

Look forward to the pics of the Camo/Flask/Pouch holder haha sounds good.

:thumbsup: i have used them for years,all good tbh and offer good prices,just make sure you get the right tk75,be it the 2600lm or 2900lm depending on what you have in mind as both listed.If you join,you can get deal emails,some good ones too with discounts.Look at some of their convoy ranges,click on new in section,then on lighting part,some new cheap bargain lights avilable with different tint options

Cells wise good too

Certainly will reg holster pouch,put No 130905773491 on bay for the pouch,i went for camo

I measured the output of my B20 ~850Lm.

Nice collection ven

Thank you FlashLion...........i am getting there:thumbsup:

So the 850lm is OTF

I will be getting the 2900Lm, will make sure to pick the right one and check out those bargain torches too! Thanks.

I checked out the pouch, looks nice and a fair price too. Nice one.

Cheers FlashLion, I'll let my mate know that I'm sure he'll be interested.

FlashLions review,these are amazing pics

http://www.candlepowerforums.com/vb/showthread.php?367200-XTAR-B20-Pilot-1x18650-Review

Goredoth said:

... In case the above is too long: How can the B20 pull three hours at 1000Lm from a single 18650 when most dual or more cell torches at even less lumen (900) can barely reach two hours?

Click to expand...

The B20 steps down quickly from turbo. Here's a run chart courtesy of njet212, from #14 in this thread:
http://www.candlepowerforums.com/vb...t-You-Can-Buy-Per-Dollar-Period&highlight=b20





Here's a couple good reviews; the first has comparative output shots over time. On high, very little drop in output for 1.5 - 2 hours.


http://www.candlepowerforums.com/vb...0-XTAR-B20-Pilot-1x18650-Review&highlight=b20

Despite the 1,000 lumen marketing hype, at the less-than $40 price, the B20 is a great value.