L1 low dead before high?

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scottaw

Enlightened
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Apr 18, 2007
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Alright this may be normal behavior, but it seems odd to me. I just got an early L1 (flood style) last week and i've been draining the battery so i can start fresh. So last night i turn the light on and nothing (so i think), keep pressing, bam, high mode. I go back to low and there is the slightest glow, so low i can look directly into it no problem.

Seems odd so i do the first thing..fresh battery, and all seems fine, low and high work. Is this how an L1 finishes off a battery? Seems like high would stop working first and leave low to get around. On a side note, when i took off the tail to change the battery there were 2 tiny squares of what looked like shiny metal sitting in the tailcap, i took them out.

So, is this a normal light, or do i have a problem? I need to know so i can return it to surefire before i start a few mods. (going to Milky, and got one of the last Oregonshooter guards!) Thanks everyone.
 
scottaw said:
Alright this may be normal behavior, but it seems odd to me. I just got an early L1 (flood style) last week and i've been draining the battery so i can start fresh. So last night i turn the light on and nothing (so i think), keep pressing, bam, high mode. I go back to low and there is the slightest glow, so low i can look directly into it no problem.

Seems odd so i do the first thing..fresh battery, and all seems fine, low and high work. Is this how an L1 finishes off a battery? Seems like high would stop working first and leave low to get around. On a side note, when i took off the tail to change the battery there were 2 tiny squares of what looked like shiny metal sitting in the tailcap, i took them out.

So, is this a normal light, or do i have a problem? I need to know so i can return it to surefire before i start a few mods. (going to Milky, and got one of the last Oregonshooter guards!) Thanks everyone.
Click to expand...
It makes sense to me. On low, there is added resistance that the battery must overcome. On high, the LED is driven more directly, with no resistance added in the circuit path.

Funny, I just logged on to post regarding runtime on low on my Seouled ML1. Over 220 hours and still going strong. Yes, I have the tailcap modification.
 
I had asked this same question regarding my previous generation L1. Size15s indicated that this was normal behavior.

I believe that it has something to do with the fact that the high mode is regulated so well, that by the time it drops off, the low mode doesn't have much left to run on.

Regarding your tail cap, I would call Surefire about it. There should be three contact prongs in there, and I had two of mine break off as well. I called them and they sent me a new cap no questions asked.
 
Thanks guys, i fel much better now, just gonna swap out a new battery, and feed this one to the red X5. And im gonna call surefire this afternoon about that tailcap.
 
In the older L1 that you refer to the high output is regulated - the juice from the battery is converted into useful juice to provide output. The low output is no regulated and so the juice does not have this assistance. Additionally, the method of switching between modes is via sensing one of two resistance states. When resistance is detected the output is passed through at the lower output. When the resistance is by-passed the output is subjected to processes (regulation).

There comes a point in as the power source is depleted when there is a 'zone' of juice remaining that is sufficient to power the regulation circuits and output in the high mode, but insufficient to power the low mode through the resister. This zone does not tend to last very long and is good indicator that the batteries need replacing.

On a related note:
Since the switching requires there to be a differential of resistance between the high and low switch positions, SureFire have gone to great lengths to ensure all sources of resistance are minimised. More about the engineering achievements can be found in the SureFire A2 'master thread'. Examples include special contact surface on the body for the TailCap switch - special alloys and plating used in the switch contacts and the spring contacts, even down to how the spring contacts are terminated to ensure good contact with the battery terminals.

It is important to keep the contacts clean so that undesirable resistance is kept to a minimum.

Al
 
Ok, al, your location is listed as england, but seriously, with ALL the information you throw around here, you're gonna tell me you don't work directly for surefire?? Thanks again for being able to answer any question we've ever had.
 
Size15's, your post was very interesting and it leads me to a question: If my L1 is in this 'zone' you speak of, where there is enough juice to run in regulation, but not enough to overcome the resistance, and I needed to make useful light as long as possible, would it be best to run the light in high mode? Once the regulation cannot create max output, does the LED simply go into direct drive? I assume from what your post says, that when the battery is almost dead, the hi mode will make light long after the low mode cannot make any due to the resitance.

If I understand you correctly, if I needed to make the longest possible use of a batter in my L1, say for an emergency situation, i would run the low mode until it could no longer make useful light, then switch over to the high mode for the remainder of the battery. Is this a correct interpretation of your post?

Thanks,
Josh
 
Josh,
I guess it could do with some experimentation.

However, if you ran the L1 with a fresh SF123A then the low mode only would give you the longest runtime - this would seem obvious.

If through mixed use - which is far more realistic use conditions, you discovered the battery had depleted into this 'zone' we're talking about, then I suspect that putting the high mode on would give you light output for longer. Once the high mode can no longer power the regulation it does drop into direct drive which I suspect is a lower-resistance route compared to the low output mode.

With the L2 the situation is different but the high output mode's output does decrease until there is no real difference between the high and low mode beams. From this state I am not sure which mode will result in the longer runtime.

Back to the L1 - if somebody has the time and means (lightmeter etc) to run a few tests we can discover actual low battery operating characteristics.

Al
 
Did they change the circuit at some point? I have a Gen4 (or so) L1. I ask because my L1 doesn't do this with depleted batts; high is gone and the light stays on low mode (for the looooooongest time).

I don't fully understand how a depleted battery can power high mode and not low. I understand the resistance pathway is by-passed, but with a depleted battery there's usually not much juice left to power the high anyway (because more current is needed to do that). At least that how all the regulation converters I've handled work. :confused:

At best, this would seem like a transitory condition. Do you have an estimate of how long one would expect to see this behavior before the battery juice can't sustain high power any more?

Size15's said:
In the older L1 that you refer to the high output is regulated - the juice from the battery is converted into useful juice to provide output. The low output is no regulated and so the juice does not have this assistance. Additionally, the method of switching between modes is via sensing one of two resistance states. When resistance is detected the output is passed through at the lower output. When the resistance is by-passed the output is subjected to processes (regulation).

There comes a point in as the power source is depleted when there is a 'zone' of juice remaining that is sufficient to power the regulation circuits and output in the high mode, but insufficient to power the low mode through the resister. This zone does not tend to last very long and is good indicator that the batteries need replacing.
Click to expand...
 
Well, i'm obviously no expert, but since i have a battery that seems to be in this zone, i'll turn the flashlight on high when i get home from work tonight. I don't think it'll last too long, and i'll keep you guys updated.
 
Thanks, Scott, that'd be useful info.

For comparison, my L1 still powered up on low about 3 months after the batt couldn't power high. That wasn't with a lot of use, but there was enough light for me to read with the light. I finally just got tired of not having high and tossed the "dead" cell.


...and Al sneeks a post as I was typing. :)
 
greenLED said:
Thanks, Scott, that'd be useful info.

For comparison, my L1 still powered up on low about 3 months after the batt couldn't power high. That wasn't with a lot of use, but there was enough light for me to read with the light. I finally just got tired of not having high and tossed the "dead" cell.


...and Al sneeks a post as I was typing. :)
Click to expand...

Interesting. My L1 (before I gutted it), would maintain the standard high output as the battery drained. The only indication that the battery was dying was when I'd click to low it would slowly fade away until I could stare into the die and just see a touch of output (probably 1/4 of a lumen). Once it reached that point, it would probably last another 60 seconds on high, and then would be totally dead.

I was going to send it in Surefire, but decided to gut it out and put in a DownBoy 1000 and a SSC P4.
 
Ok, runtime test completed. I took the battery mentioned above, turned the L1 on high at 11:45, and browsed around CPF. I was thinking it was getting dimmer slowly, still well above the normal "low" mode. and at 12:00 it abruptly shut off. Didn't finish dimming down, just turned right off. I would guess it was about 10 lumens when it went off. Let it rest for a minute, absolutely NO light on high or low mode. So someone smarter than me can now explain what happened.

On a side note to anyone interested, same battery works in my red X5, but it's MUCH dimmer than fresh, but still plenty of light to read, maybe even get around.
 
For what it's worth, I did call Surefire back at the beginning of the year to ask them what the proper behavior of the L1 was. The guy I talked to said that the high mode should drop off first, leaving you with the low mode for a long, but unspecified length of time.

I was going to send it in, but decided to upgrade it instead. Of course, the person I talked to could be incorrect, but I never pursued it any further.
 
Based on reading the old threads about moon-mode and runtime for the L1, I would have guessed the same - that high mode would disappear leaving the unregulated low and gradually diminishing mode. That's why I was surprised when I found the same thing described earlier in two L1s at the same time (coincidence that they both got low batteries at the same time).
 
From the OP and Al's comment, this behavior may be exclusive to the older L1's. Like I mentioned before, mine works as the SF rep you talked to described.

It could also be individual unit variation. You know, like those U2's that will "strobe" in between modes (you gotta hit the "sweet spot" as you turn the selector ring to see it), whereas other units have a sharp transition between modes.
 
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