not sure what to think of this, but....

[hotlight]

I recieved my lf3xt with aa tube yesterday. Was running fine when I first fired it up.(during the day). When it got dark I was ready to do some comparisons with my RRT-0.

I had both pointed at a white wall inside the house at max. brightness. Kept them both on as I walked towards my backyard, they were both in my left hand(touching eachother). As I approached the back door, the LF3XT went dim.(rough guess, 40 lumens on max, each level was lower than it should be)..... tried new batteries(fresh eneloops, alkaline aa's, and even bought a cr123 for $6 from target), disassembled the light, cleaned the threads/lubed....still the same problem. also, reset to factory defaults.( I've had a lf2xt for 4 months, so, I'm %100 it is not a programming issue that I would have caused)

I have no clue what happened.... all the functions work, but it just isn't as bright as it should be.(like stated, probably 30-40 lumens highest setting, rough guess.) I can look directly into the led at it's new %100 high level.


this may sound crazy, but: could holding both the lights too close together have caused this? they were touching eachother(both lf3xt and jb rrt-0 on MAX.).... I think it was a coincidence, but thought I'd ask.

what is usually the cause of lights functions working properly, but the LED (edit: not) shining at %100?


I already mailed the light back to the seller, and they seem to be doing the right thing. Actually very quick email responses.

 

[csshih]

odd. I don't think that is really possible.. I sometimes carry lights to and from places all in one hand.. nothing has ever broken.

 

[jimmy1970]

I had a LF3Xt that had a similar problem. It would have normal brightness on a RCR123 cell with the higher voltage but on a 3.0v primary, the lights' brightness was only a fraction of its proper output. Turns out the boost converter had died - I never got around to getting it fixed -its' sitting in a draw around here somewhere. I sort of lost interest in the Liteflux lights after that episode.

James....

I recieved my lf3xt with aa tube yesterday. Was running fine when I first fired it up.(during the day). When it got dark I was ready to do some comparisons with my RRT-0.

I had both pointed at a white wall inside the house at max. brightness. Kept them both on as I walked towards my backyard, they were both in my left hand(touching eachother). As I approached the back door, the LF3XT went dim.(rough guess, 40 lumens on max, each level was lower than it should be)..... tried new batteries(fresh eneloops, alkaline aa's, and even bought a cr123 for $6 from target), disassembled the light, cleaned the threads/lubed....still the same problem. also, reset to factory defaults.( I've had a lf2xt for 4 months, so, I'm %100 it is not a programming issue that I would have caused)

I have no clue what happened.... all the functions work, but it just isn't as bright as it should be.(like stated, probably 30-40 lumens highest setting, rough guess.) I can look directly into the led at it's new %100 high level.


this may sound crazy, but: could holding both the lights too close together have caused this? they were touching eachother(both lf3xt and jb rrt-0 on MAX.).... I think it was a coincidence, but thought I'd ask.

what is usually the cause of lights functions working properly, but the LED shining at %100?


I already mailed the light back to the seller, and they seem to be doing the right thing. Actually very quick email responses.

 

[hotlight]

"boost converter"- why didn't I think of that?
the term itself makes sense... not boosting and converting correctly.

thanks, I'll ask the seller to check the boost converter.



so, if I run my light with rcr123(3.7V), my light will not need/use the boost converter?
(bypass it because the light is running on the max voltage it was designed for, therefore, doesn't need to boost or convert the lower voltage batteries to operate/regulate the output of the light)? did that make sense?

only the lower voltage batteries will need the boost converter?

Im trying to learn but the electronics is a hard concept for me to grasp.

 

[timberwolf]

The part of the boost converter which most likely has failed is the charging transistor of the storage inductor. Its highly likely that it will die out completely later so I would recommend you get a replacement.

As for the need of the boost converter:
A LED has a rather high forward voltage which must be overcome to ge a current flow through the LED. This voltage is usually somewhere in the range of 2.5V to 3.7V so a freshly charged LiIon with about 4.2V has a high enough voltage to power the LED without a boost converter. But as this voltage drops with used up charge (and also current but thats another story) it may drop below the forward voltage of the LED before the whole battery capacity is used up.

Long story short, you will get lower total light output and shorter runtime, independent of the battery type (rechargeable or primary).

Hope this wasn't to complicated, if so feel free to ask.

 

[hotlight]

The part of the boost converter which most likely has failed is the charging transistor of the storage inductor. Its highly likely that it will die out completely later so I would recommend you get a replacement.

As for the need of the boost converter:
A LED has a rather high forward voltage which must be overcome to ge a current flow through the LED. This voltage is usually somewhere in the range of 2.5V to 3.7V so a freshly charged LiIon with about 4.2V has a high enough voltage to power the LED without a boost converter. But as this voltage drops with used up charge (and also current but thats another story) it may drop below the forward voltage of the LED before the whole battery capacity is used up.

Long story short, you will get lower total light output and shorter runtime, independent of the battery type (rechargeable or primary).

Hope this wasn't to complicated, if so feel free to ask.

thanks.
no you made it easy to understand, thanks again.
from how I'm "picturing" it due to your description, the boost regulator is the "meat and potatoes" of regulated runtimes and output, and is necessary even with li ions.

any suggestions of testing the new/"fixed" light when I recieve it?(would running on max with rcr123, for lets say 5 hours, determine that I should not have a problem for a while?)

could switching thru the different modes too fast have caused this? I'm puzzled as to what causes this.

bad QC?(the light worked fine for the 1/2 hr I played with it before night, cant imagine them testing each and every light for this long) or just 1 in 100 bad luck?

I also lost a little faith in LF jimmy1970, but, still have confidence in my LF2XT. has never failed me.

 

[timberwolf]

any suggestions of testing the new/"fixed" light when I recieve it?(would running on max with rcr123, for lets say 5 hours, determine that I should not have a problem for a while?)

Use the 2AA tube with freshly charged NiMh cells, set the light 100% and let it run down while standing on the table. Thats the most stressing test I can think of, the low voltage of the NiMh cells puts stress on the boost converter, the standing on the table doesn't conduct many heat away so a weak transistor is more likely to fail (due to higher on-state resistance a elevated temperatures). If it survives that test, its likely that it will simply last.

could switching thru the different modes too fast have caused this? I'm puzzled as to what causes this.

You didn't do anything wrong. The most likely cause is a bad(high on-state resistance) transistor. It's difficult but not impossible to QC this, but I doub't that many if at all manafacturers do any deep testing on their production run lights.
What happens is that, due to the high resistance, power is lost at the transistor in the form of heat, as the transistor then starts heating itself this effect drastically gets worse and at some point the bonding connections or the silicon chip itself simply "burn out".

I once did a deep circuit analysis of a LF3XT pill which failed on me, the effect was more drastically for me: no more light at all.
In my case there also was the distinct smell of fried chip packages at the head

 

[LED Cool]

I had a LF3Xt that had a similar problem. It would have normal brightness on a RCR123 cell with the higher voltage but on a 3.0v primary, the lights' brightness was only a fraction of its proper output. Turns out the boost converter had died - I never got around to getting it fixed -its' sitting in a draw around here somewhere. I sort of lost interest in the Liteflux lights after that episode.

James....

please send the LF3XT head to me. i will get it fix for you free of charge. please PM me for address.

khoo

 

[jimmy1970]

please send the LF3XT head to me. i will get it fix for you free of charge. please PM me for address.

khoo

Thank you for your offer of help. I will search for it today and let you know when I find it.

I will be in touch,

Thanks again,

James....

 

[hotlight]

Use the 2AA tube with freshly charged NiMh cells, set the light 100% and let it run down while standing on the table. Thats the most stressing test I can think of, the low voltage of the NiMh cells puts stress on the boost converter, the standing on the table doesn't conduct many heat away so a weak transistor is more likely to fail (due to higher on-state resistance a elevated temperatures). If it survives that test, its likely that it will simply last.


You didn't do anything wrong. The most likely cause is a bad(high on-state resistance) transistor. It's difficult but not impossible to QC this, but I doub't that many if at all manafacturers do any deep testing on their production run lights.
What happens is that, due to the high resistance, power is lost at the transistor in the form of heat, as the transistor then starts heating itself this effect drastically gets worse and at some point the bonding connections or the silicon chip itself simply "burn out".

I once did a deep circuit analysis of a LF3XT pill which failed on me, the effect was more drastically for me: no more light at all.
In my case there also was the distinct smell of fried chip packages at the head

thanks for the responses timberwolf.

does anyone object to this sort of "testing"?(that's like buying a brand new car and accelerating as fast as you can, braking as hard as you can-when the manual tells you to go 55mph for X amount of miles, you see what Im getting at)


another question, as far as durability:
when a light is hot(ex. lf3xt run for high rcr123 for 20 min), is it more likely to fail if dropped/shocked?(due to "insides" being hot and connections breaking more easily)

when is a light at it's most vulnerable under "real life conditions"?


I smelt something like that too.... a distinct smell. Why are we smelling flashlights?

 

[timberwolf]

thanks for the responses timberwolf.
does anyone object to this sort of "testing"?(that's like buying a brand new car and accelerating as fast as you can, braking as hard as you can-when the manual tells you to go 55mph for X amount of miles, you see what Im getting at)

There aren't any parts in a flashlight that first must break in like a cars engine

another question, as far as durability:
when a light is hot(ex. lf3xt run for high rcr123 for 20 min), is it more likely to fail if dropped/shocked?(due to "insides" being hot and connections breaking more easily)

when is a light at it's most vulnerable under "real life conditions"?

A flashlight shouldn't get so hot that solder connections start getting weak.
The most danger to a flashlight are drops, more precisely the sudden stop at the ground. You get really high G forces when you decelerate in just half a millimeter

I smelt something like that too.... a distinct smell. Why are we smelling flashlights?

That smell comes from the plastic chip package of the transistor in your case, another bad smelling component is an electrolytic capacitor, but i doubt one failed in your flashlight.

 

[hotlight]

There aren't any parts in a flashlight that first must break in like a cars engine

yeah, yeah, I know.... just trying to think of an example. I will try this "test" when I get my light back.


A flashlight shouldn't get so hot that solder connections start getting weak.
The most danger to a flashlight are drops, more precisely the sudden stop at the ground. You get really high G forces when you decelerate in just half a millimeter

what I figured also(drops are most hazardous).....


That smell comes from the plastic chip package of the transistor in your case, another bad smelling component is an electrolytic capacitor, but i doubt one failed in your flashlight.

thanks again:thumbsup:... definately helping me understand