Led Lenser P7.2 pics & thoughts

[TCY]

Good torch, really wide beam!

A question regarding the lens. Have you noticed with other lenser models that the lens leaks some light to decoration ring? Is it a drawback from extending the wide end of the zoom, or is it new designed feature to leak some light through lens on the red decoration ring? slight intensity loss can be seen with sealing bounce when zooming. Nevertheless this is by far the widest beam i have seen on lensers


The thing that bothers me is that i assumed 7.2 is not resistor regulated any more, but it still is. Thing that is the most tricky one is how can the led survive as there are zero resistance measured (measured from the cartridge connections that connects to the button) when button is pressed all the way? People do use high end rechargeables on it, like on P7's, and those are well capable of driving destructive current to led. How can it survive?

I took a photo of it. But just can not find a way to attach it here..

One thing I forgot to mention, lens-based flashlights like P7.2 will have some LED lumens wasted in the light redirecting process, and these left over lumens light up the little red dots. Or at least I imagine.

 

[Kyle_PL]

As a person who suffered from constantly dimming incandescent flashlights in childhood, I'm pretty confident to say that electrical regulation is a must have feature in modern LED flashlights,

I'm using Ni-Mh in LED Lenser P7.2 . Ni-MH have maybe not perfect, but quite flat voltage discharge curve ( flat, rotated "S" ). ... so, this "constantly dimming" is not so constant dimming on Ni-Mh I'm using this LED Lenser from yesterday, so I will check brightness drop in very near future (I have Fenix E40 for comparison which have brightness stabilisation, and powered by Ni-MH too ).

 

[R_finland]

Thanks Norm. Anyhow l'll forget the photo for now. It is way too complicated for regular IT-guy like me to get it published first, then link here Light leakage anyway can be so clearly seen, when the torch is all the way retracted. Anyone will see it who owns LLP72.

That was good to remind again that regulator circuits (without a voltage indicator, or clear "behaviour" when batteries become flat) are harsh for the rechargeables. Brings back memories from fenix L2D which thought me how destructive reversing cell polarity really is. So in this case light starts to dim earlier than with regulator, indicating that is time to charge.

Everyone seems to have their own preferences what comes to the beam pattern I use lensers mostly with wide. The evenly lit area is good for me and helps a lot when photographing in low light conditions. The narrow beam has not so good taste for me. it is too strict on the edges. I really prefer some spill around the hot spot. On the other hand, strict beam is not blinding you when looking in to pipes, tanks etc. Pros and cons

All in all. I give good word for LLP7.2. Simple to use, can be operated with gloves on. Gives decent output. Batteries do not last long, but i'm not using it all the night like hikers perhaps.

 

[TCY]

I'm using Ni-Mh in LED Lenser P7.2 . Ni-MH have maybe not perfect, but quite flat voltage discharge curve ( flat, rotated "S" ). ... so, this "constantly dimming" is not so constant dimming on Ni-Mh I'm using this LED Lenser from yesterday, so I will check brightness drop in very near future (I have Fenix E40 for comparison which have brightness stabilisation, and powered by Ni-MH too ).

Don't get me wrong, I Still love my P7.2 and I put ni-mh rechargeables in it as well. The constant dimming process is less noticeable indeed(still noticeable though, as I play with it 20-30 times a day), but I still prefer a regulated light. Besides, P7.2 is a little too large and heavy for pocket EDC. Whenever I EDC it my pocket looks ultra big and my pants keep dropping if I'm not wearing a belt.

 

[TCY]

Thanks Norm. Anyhow l'll forget the photo for now. It is way too complicated for regular IT-guy like me to get it published first, then link here Light leakage anyway can be so clearly seen, when the torch is all the way retracted. Anyone will see it who owns LLP72.

That was good to remind again that regulator circuits (without a voltage indicator, or clear "behaviour" when batteries become flat) are harsh for the rechargeables. Brings back memories from fenix L2D which thought me how destructive reversing cell polarity really is. So in this case light starts to dim earlier than with regulator, indicating that is time to charge.

Everyone seems to have their own preferences what comes to the beam pattern I use lensers mostly with wide. The evenly lit area is good for me and helps a lot when photographing in low light conditions. The narrow beam has not so good taste for me. it is too strict on the edges. I really prefer some spill around the hot spot. On the other hand, strict beam is not blinding you when looking in to pipes, tanks etc. Pros and cons

All in all. I give good word for LLP7.2. Simple to use, can be operated with gloves on. Gives decent output. Batteries do not last long, but i'm not using it all the night like hikers perhaps.

I"m not sure if it's just me, but whenever I pull the lens back and try to use the "wide" beam profile, the yellow part of the spectrum get pushed outside, leaving the centre tint almost purple. If LL can fix this in the future with their P7.3 or something, then I'll definitely pay a premium for it.

In general, P7.2 is indeed a good light, or at least for non flashaholics, as I learned that many people here don't like LL products. My non-flashaholic friends think P7.2 is a miracle though.

 

[StorminMatt]

As a person who suffered from constantly dimming incandescent flashlights in childhood, I'm pretty confident to say that electrical regulation is a must have feature in modern LED flashlights, and its pros greatly outweight its cons. But again that is only my personal preference, and I respect your opinion.

Incandescents are a completely different animal from LEDs. One HUGE difference is that, while LEDs experience an increase in efficiency as power levels drop, incandescents experience a HUGE decrease in their ability to generate visible light (a cooler filament means that more energy is being released in the infrared range). So as batteries run low, LEDs don't dim as much. And although LEDs can tint shift when underdriven, color does not change NEARLY as much in an underdriven LED as in an underdriven incandescent. Both of these factors mean that an LED is going to operate in a MUCH more satisfactory manner at lower voltages than an incandescent, even if the LED is not running from a regulated supply. If younadd to this batteries that produce a fairly constant discharge voltage (ie NiMH or LiFePO4 rather than alkaline or LiCo/LiMn), then regulation really isn't that necessary.

 

[Mr Floppy]

I'm not sure what is the led exactly that P7.2 uses. What i searched from Cree's datasheets i think it is 1,5A/3.1V (continuous/hot) rated.

From the image posted above, it has the silvery circuit board under the LED and a square notch in the corner so I think it will be either a XP-E2 or XP-G2. From the size of the die, I'm thinking it is a XP-G2 and that would certainly fit with the 1.5A. If it's a XP-E2, then it's over-driven.

 

[TCY]

Incandescents are a completely different animal from LEDs. One HUGE difference is that, while LEDs experience an increase in efficiency as power levels drop, incandescents experience a HUGE decrease in their ability to generate visible light (a cooler filament means that more energy is being released in the infrared range). So as batteries run low, LEDs don't dim as much. And although LEDs can tint shift when underdriven, color does not change NEARLY as much in an underdriven LED as in an underdriven incandescent. Both of these factors mean that an LED is going to operate in a MUCH more satisfactory manner at lower voltages than an incandescent, even if the LED is not running from a regulated supply. If younadd to this batteries that produce a fairly constant discharge voltage (ie NiMH or LiFePO4 rather than alkaline or LiCo/LiMn), then regulation really isn't that necessary.

Wow thanks for the thourough explanation. As you can see I still have much to learn.

 

[StorminMatt]

Wow thanks for the thourough explanation. As you can see I still have much to learn.

On the other hand, keep in mind that regulation becomes more important when using batteries with more steeply dropping voltage. Regulation is therefore more important in lights that use Li-Ion batteries (other than LiFePO4). Also, regulation is obviously necessary in lights that can run on a variety of voltages (like 1xAA lights that can use 14500s). But a basic light running on NiMH batteries can do without it, and may actually be more efficient without it when losses are factored in.

 

[TCY]

On the other hand, keep in mind that regulation becomes more important when using batteries with more steeply dropping voltage. Regulation is therefore more important in lights that use Li-Ion batteries (other than LiFePO4). Also, regulation is obviously necessary in lights that can run on a variety of voltages (like 1xAA lights that can use 14500s). But a basic light running on NiMH batteries can do without it, and may actually be more efficient without it when losses are factored in.

Led Lenser warns its customers not to use Ni-mh and Lithium batteries, but it looks like no one would listen.
So if a flashlight eats batteries with flat voltage dischrage curve, regulation is not that important as the dimming effect is not very apparent?

 

[StorminMatt]

That's what I've found. I actually have a few Lenser lights, including the HP550, P14, PX25, and a number of those 'free' G10's. And I've found that, when run on NiMH, I really don't notice them dimming until the batteries are pretty much spent. By the way, whenI use them, ImALWAYS run them on NiMH. And they still work.

 

[TCY]

That's what I've found. I actually have a few Lenser lights, including the HP550, P14, PX25, and a number of those 'free' G10's. And I've found that, when run on NiMH, I really don't notice them dimming until the batteries are pretty much spent. By the way, whenI use them, ImALWAYS run them on NiMH. And they still work.

I just did an experiment with my P7.2 using a set of ni-mh rechageables with around 50% juice left and a set of brand new alkalines. turns out the brightness difference is significant. I bet that the dimming effect is worse with a set of dying alkaline batteries though.

 

[StorminMatt]

I just did an experiment with my P7.2 using a set of ni-mh rechageables with around 50% juice left and a set of brand new alkalines. turns out the brightness difference is significant. I bet that the dimming effect is worse with a set of dying alkaline batteries though.

With a relatively low draw light, fresh alkaline batteries will produce greater initial output. But only for maybe 5-10 minutes. It doesn't take very long before brightness on alkaline batteries actually drops below that with NiMH. NiMH holds MUCH better brightness. And NiMH will always be brighter than alkaline batteries provided the current draw is sufficiently high. For instance, I don't think alkaline batteries will EVER produce greater output than NiMH with an SC52 on high.

 

[TCY]

With a relatively low draw light, fresh alkaline batteries will produce greater initial output. But only for maybe 5-10 minutes. It doesn't take very long before brightness on alkaline batteries actually drops below that with NiMH. NiMH holds MUCH better brightness. And NiMH will always be brighter than alkaline batteries provided the current draw is sufficiently high. For instance, I don't think alkaline batteries will EVER produce greater output than NiMH with an SC52 on high.

That's why everyone ignores LL's "USE ALKALINES ONLY OR YOU ARE SCREWED"warning

 

[StorminMatt]

That's why everyone ignores LL's "USE ALKALINES ONLY OR YOU ARE SCREWED"warning

That, and the fact that (1) alkaline batteries cost you every time you use them, and (2) they tend to leak and destroy your expensive Lenser light. Of course, I suspect Lenser wants you to use alkaline batteries for the second reason. Repeat business is ALWAYS a good thing for them.

 

[TCY]

That, and the fact that (1) alkaline batteries cost you every time you use them, and (2) they tend to leak and destroy your expensive Lenser light. Of course, I suspect Lenser wants you to use alkaline batteries for the second reason. Repeat business is ALWAYS a good thing for them.

LL lights rely on alkaline battery's high internal resistance-hence low current capability to work as a regulation to prevent excessive current going to the LED, causing damage.
Hmmm that's what I learned from posts and posts.

 

[Kyle_PL]

LL lights rely on alkaline battery's high internal resistance-hence low current capability to work as a regulation to prevent excessive current going to the LED, causing damage.
Hmmm that's what I learned from posts and posts.

But alkaline battery's have higher voltage (at least at the beginning), so more overall power (wattage) going to the LED "causing damage". ...

 

[inetdog]

Open circuit voltage alone does not necessarily cause more current to flow. Nor even enough current that the LED voltage is somehow higher.

Sent from my XT1080 using Tapatalk

 

[StorminMatt]

But alkaline battery's have higher voltage (at least at the beginning), so more overall power (wattage) going to the LED "causing damage". ...

But not for long. Within a few minutes, voltage is WAYYYY down with alkalines. Especially if current draw is the better part of an amp.

 

[Chodes]

But alkaline battery's have higher voltage (at least at the beginning), so more overall power (wattage) going to the LED "causing damage". ...

Internal resistance beats the voltage (to achieve what LL want)

Example would be old school direct drive SSC P7 (no pun intended)
1 x LION (3.7V Nominal) will drive to around the LED's spec'd 2.8A.
4 x AA Alkalines,(6.0V Nominal) much higher volts, will result in more like 0.5A to LED.
3 x NiMh C cells (3.6V Nominal) would result in highest current to LED, most likely over 3Amps.

In that example the lower the voltage, the higher the current.