(SOLVED) Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Solution for this problem (discovered this later).
Solution: i tightened the tailcap so hard as i could, and now the issue is gone. The issue is now gone for a month so i can say that this is the solution. The quality of Klarus is very very good and after using this light a month i can say that its the best ive had!

Hi guys and girls,

This week i received the new Klarus XT2CR, im impressed with this light and the light itself is very nice!

However i have a question, (the strange thing is that sometimes this happens and sometimes not l, i tested multiple times on/off and with alot of time between the tests). Directly after i turn on the light in turbo mode after 1 second the light will lower the output (i think from seeing it with my eyes 100 or 200 lumen drop?).
- Is this light i.e. starting in 1800lumen and dropping to 1600 lumen because of the regulation in the light, or is it dropping from i.e. 1600 towards 1500 i have no measurement equipment for this. But i know that the Concept1 is using the same led type and gets 1800 lumen out of it.
I know that there is an internal tempreture sensor but dimming the output 1 second after i turn the light on in turbo, is that normal behavior? The ambient weather temprature is arround 12 celcius so its not that warm here. The strange thing is that (i tested it multiple times) sometimes it dims after 1 sec on turbo and some time not... very strange what can cause this issue? Im using the 3600mah Klarus 18650 and also tested it with other high drain batterys but the same issue, so its something in the light right, that causes this?

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

I doubt many other people have received this light yet to comment. I have one the way from GearBest for review, and will do a runtime test on turbo.

I will note that given your username is that of a rival manufacturer's flagship product, that some bias could be perceived in your post.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Nice, please test also multiple times, maybe its just that the light is starting in 1800 and lowers the output to 1600 however then its still strange that it sometimes happens and sometimes not. I also have the Concept1 but i like the desing but not the light because, the concept1 has only a side button very anoying and the concept1 is dropping very fast in output. Thats the reason why i bought the XT2CR. It seems that the XT2CR can hold longer turbo, i will also do a runtime measurement in the future.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Have you checked the voltage of the cell? Charged prior to use as come around 3.6/3.7 storage v. Maybe initial burst before settles which i can notice on some lights, very minor drop and settles if makes sense.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

ven said:

Have you checked the voltage of the cell? Charged prior to use as come around 3.6/3.7 storage v. Maybe initial burst before settles which i can notice on some lights, very minor drop and settles if makes sense.

Click to expand...

Nope, i just charged the batterys and put them inside the light.
What do you mean with 'initial burst before settles'? Thanks

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

On certain lights, i have seen the max output drop ever so slightly(hard to explain and not with all lights, think more driver dependent). Hard to say with your light, if its quite noticeable then something is not quite right.

What is the actual battery being used? For around 1600-1800lm and to sustain that level for a few mins before step down, you will need a minimum of 10a rated 18650. Minimum along the lines of a sanyo GA cell(10a 3500mah).

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

ven said:

On certain lights, i have seen the max output drop ever so slightly(hard to explain and not with all lights, think more driver dependent). Hard to say with your light, if its quite noticeable then something is not quite right.

What is the actual battery being used? For around 1600-1800lm and to sustain that level for a few mins before step down, you will need a minimum of 10a rated 18650. Minimum along the lines of a sanyo GA cell(10a 3500mah).

Click to expand...

I used the battery that comes with this light the 18GT-36 (See specs here:
http://www.candlepowerforums.com/vb...-18GT-36-KLARUS-FIRST-WITH-IMR-18650-FUNCTION).

I also tested it with the Nitecore NL1835HP (see specs here: http://www.candlepowerforums.com/vb/showthread.php?436171-New-Product-Announcement-Nitecore-NL1835HP).

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

I have one in my possession as of yesterday. I will test and report back today to give you one more data point.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Well if sometimes it happens and sometimes it doesn't, then obviously that is not normal.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

busseguy said:

Well if sometimes it happens and sometimes it doesn't, then obviously that is not normal.

Click to expand...

This evening i again tested the XT2CR, and the issue was there again. Is it possible that it has to do with the outside tempreture, it is now here 10 celcius (50 fahrenheit) here in The Netherlands so is it possible that due to the cold weather the battery performance is affecting the output?

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

CONCEPT1 said:

This evening i again tested the XT2CR, and the issue was there again. Is it possible that it has to do with the outside tempreture, it is now here 10 celcius (50 fahrenheit) here in The Netherlands so is it possible that due to the cold weather the battery performance is affecting the output?

Click to expand...

But you have the light and battery indoors beforehand, right? If so, there's no way the outdoor temp can affect the battery in 1 second. 10C is also not cold; you'd need at least 30 minutes at 0C before the cold could get to and really impact the battery.

I tested mine just now and there was no visible stepdown in the first 45 seconds.

I'd suggest you double check the battery voltage (4.15-4.20 fully charged) and if it still steps down, I'd say it's time to send it back.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Just tested. Call it 50 lumen gradual drop over 60 sec, no visible step. At 60 sec, stepdown is dramatic.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?


I made a gif i hope you can see the issue. I didnt film the beam directly because my phones camera is not the best. So i filmed the side beam.
https://imgflip.com/gif/1vltko ook

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

CONCEPT1 said:

I made a gif i hope you can see the issue. I didnt film the beam directly because my phones camera is not the best. So i filmed the side beam.
https://imgflip.com/gif/1vltko ook

Click to expand...

I tested again and found out that, when you unscrew the tailcap and screw it back on the light is performing as it should be, however unfortanutely after 1 till 2 hours without doing anything the light will again lower the output after 1 sec.... But its very strange that after unscrewing the light is temporary performing as it should be. I think maybe this has something to do with the circuit? Maybe you guys can test it also when the battery is longer inside the light, maybe you will see then the same behavior?

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

CONCEPT1 said:

I tested again and found out that, when you unscrew the tailcap and screw it back on the light is performing as it should be, however unfortanutely after 1 till 2 hours without doing anything the light will again lower the output after 1 sec.... But its very strange that after unscrewing the light is temporary performing as it should be. I think maybe this has something to do with the circuit? Maybe you guys can test it also when the battery is longer inside the light, maybe you will see then the same behavior?

Click to expand...

I tried again after letting it sit for 3 hours or more. (Didn't time it... it was enough time to take the boat out for some wakesurfing and get back in).

Anyway, same power curve as before for me. No visible step at all until 66 seconds this run.
Over the first 60 seconds about 50 lumens were lost, but that's why ANSI tests at 30 seconds instead of turn on. But anyway those lumens lost were very gradual and linear...no stepdown.

I think you got a bad unit.

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Same thing happens to mine. I noticed the first day I got it. Immediately after I start the light it will step down to a lower output. Not a big step down but enough for my eyes to notice. Like yours mine doesn't do it all the time either bUT happens quite often. My battery indicator also has small intrusions inside of it. It'll turn green for full then a green with a hint of red( supposed to be yellow) for the medium and then completely red for low battery. Even though there is a difference between full battery and medium it is not aesthetically pleasing.don't get me wrong i Love the light, performs well and looks great. Maybe I'm being a little nit picky Here's a pic of the intrusions in battery indicator light hope you can see it.
https://imgflip.com/i/1voqor

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Gea2427 said:

Same thing happens to mine. I noticed the first day I got it. Immediately after I start the light it will step down to a lower output. Not a big step down but enough for my eyes to notice. Like yours mine doesn't do it all the time either bUT happens quite often. My battery indicator also has small intrusions inside of it. It'll turn green for full then a green with a hint of red( supposed to be yellow) for the medium and then completely red for low battery. Even though there is a difference between full battery and medium it is not aesthetically pleasing.don't get me wrong i Love the light, performs well and looks great. Maybe I'm being a little nit picky Here's a pic of the intrusions in battery indicator light hope you can see it.

https://imgflip.com/i/1voqor

Click to expand...

Today i tightened the tailcap so hard as i could, and now the issue is gone. But, because the issue was sometimes there and sometimes not i cannot confirm that this is the fix.

I discovered another issue, maybe you can check your light also.
My light has only Turbo, High and Medium, i can only cycle between 3 modes (and this light should have 4 including low). This sucks because sometimes low (10 lumens) is handy. The XT2CR is a very nice concept, but in practice im dissapointed and this is my first (and maybe last) experience with Klarus! Quality is a very important aspect for me...

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

CONCEPT1 said:

Today i tightened the tailcap so hard as i could, and now the issue is gone. But, because the issue was sometimes there and sometimes not i cannot confirm that this is the fix.

I discovered another issue, maybe you can check your light also.
My light has only Turbo, High and Medium, i can only cycle between 3 modes (and this light should have 4 including low). This sucks because sometimes low (10 lumens) is handy. The XT2CR is a very nice concept, but in practice im dissapointed and this is my first (and maybe last) experience with Klarus! Quality is a very important aspect for me...

Click to expand...

Let's see if this works... normally I don't post from mobile.


As you can see, I did a poor job of holding still... but there is no stepdown.

I have noticed the tail cap has to be quite tight. Most lights the tail tightens to a hard stop. In this one the resistance just grows at the end.

To the modes, the manual explains it how to switch between 4 and 3 mode options. Hold the paddle switch down 10 seconds and the press the power switch (then let both go).

Re: Klarus XT2CR is dimming in output after 1 second on, normal behavior or not?

Nice it worked!! Guess my tail cap was a bit loose no more instant stepdown! As for the brightness levels mine has 4. Low medium high and turbo. I keep mine on the outdoor mode because I'd rather have instant low rather than instant strobe. Tactical mode has instant strobe and 3 brightness settings (low high turbo). So I'm guessing yours is on tactical mode. I love my klarus lights and have never had a problem with them. Has anyone had trouble with their battery indicator lights?