More battery efficient flashlight, is there such a thing?

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dee-u
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More battery efficient flashlight, is there such a thing?

For instance, flashlight1 and flashlight2 uses the same battery and as lighted on the same lumens (200 lumens perhaps), would there be an instance where flashlight1 will last longer than flashlight2?

niajef
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yes. depends on the LED outputting that 200 lumens, and depends on the driver

dee-u
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niajef wrote:
yes. depends on the LED outputting that 200 lumens, and depends on the driver

Thank you for the very prompt response. What are the types of LED/drivers which are more energy efficient? I am actually curious since I am after a longer runtime when looking for flashlights.

bobvoeh
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It would seem my monitor has a bug inside of it now.

dee-u
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bobvoeh wrote:
It would seem my monitor has a bug inside of it now.

You will be fine as long as you will not hit it with a hammer. Big Smile

niajef
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dee-u wrote:
niajef wrote:
yes. depends on the LED outputting that 200 lumens, and depends on the driver

Thank you for the very prompt response. What are the types of LED/drivers which are more energy efficient? I am actually curious since I am after a longer runtime when looking for flashlights.

LEDs i dont know, but im sure tons of people on here would know, drivers, buck and boost would be considered efficient compared to the cheaper FET and linear

iamlucky13
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A variety of users have done their own tests of flashlight output and runtime, which can be used to calculate efficiency. Because the accuracy of each person’s gear may varied, they shouldn’t be assumed to be exact comparisons, but can help give a sense.

Zak is one such reviewer, and a member here, and often will take the effort to calculate efficiency. I think this might have been the highest efficiency model he tested:

https://zakreviews.com/thrunite-tc20v2.html

Lumen9000
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Lights with Xhp 70.x or xhp35hi will always need boost drivers to work and most often sustains over 1000 lumen with ease.also look into convoy m21E and convoy M3-c.

YuvalS
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the answer is in Lumen to Amper  graph


And easier to understand using lumen to Amper  to lumen 

This data is for XM-L2 but all leds have similar behavior

1. Obviously the beter lumen to amp ratio the more efficient the led so first step to increase efficiency is by choosing best emitter with lumen to amp (or lumen to watt) ratio   
2. As you can see it starts linear. ie constant lumen to amp ratio - it called "linear section" and for this range of amps the LED is more efficient so you want to keep your light in this range
Your question is for 200 lm so you can think that you are in the linear section but it is only true for constant current drivers.
PWM driver actually working in the highest current allowed by driver so far off the linear section so 2nd way to improve efficiency is using constant current driver
3. we now now that led is more efficient on lower currents so 3rd way to improve efficiency is to divide the same current among more LEDs instead of driving 1 led with 3amps fo 1000 lm, drive 3 leds with 700amp each and get tand get combined 1000 lumens output for only 2.1amp 

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Quadrupel
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First you have to keep constant 200 lumen, so you need stabilized output driver. Read more about DC-DC converter types. About linear and switching topology . Its important to use low resistance contacts and switches. Overpowered led is loosing efficiency too and so on.. Its whole science about it Smile
dee-u
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Thank you guys, I will need more time to digest the knowledge you’ve imparted. Some terms used are greek to me.

how crazy is this
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I am not sure how to express this but there is one thing that has always completely amazed me in terms of efficiency and that is useful light per watt. By that I mean that most of my lights at say 80 or 100 mA will be very useful flashlights. Bump that up to an Amp and they are really putting out some light and of course if your looking for throw it may be required. However, 10X the energy for an apparent doubling or so in perception makes the lower levels seem fantastically more efficient to me. I believe that this goes beyond the efficiency differences at lower levels and gets to perceived brightness as well. What to they say something like 4X the lumen to seem 2X as bright?

Lightbringer
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bobvoeh wrote:
It would seem my monitor has a bug inside of it now.

It’s not a bug, it’s a feature.

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wle
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how crazy is this wrote:
I am not sure how to express this but there is one thing that has always completely amazed me in terms of efficiency and that is useful light per watt. By that I mean that most of my lights at say 80 or 100 mA will be very useful flashlights. Bump that up to an Amp and they are really putting out some light and of course if your looking for throw it may be required. However, 10X the energy for an apparent doubling or so in perception makes the lower levels seem fantastically more efficient to me. I believe that this goes beyond the efficiency differences at lower levels and gets to perceived brightness as well. What to they say something like 4X the lumen to seem 2X as bright?

something like that
it is not linear, as you found out
100 lumens does not seem twice as bright as 50

the leds also start to be less efficient at higher currents

1 watt in might be 200 lumens out

but 10 watts in might be 1200, , instead of 2000

wle

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Zebralight SC700d is very good, even though it’s taking about 30% hit from high cri led. There’s a Fenix that’s 21700 and XHP70.2 (low cri) if the Thrunite, linked above, with 26650 isn’t to your liking.

Acebeam E70 is another good one.

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rayfish wrote:
Take a 2×18650/CR123 (Buck Driver) Flashlight with ramping and top lumen Chip or “PC green” (from phosphor), and use it at as low as possilbe.

Yep, and the nice thing about PC green is that even though it’s a dominant green, it’s not perfectly monochromatic, so you’re not seeing just a stark green’n‘black, but can still see some other colors from red to blue just fine, albeit subdued.

I got a pair of Anekim UC20 and UC10 with PC green emitters, and they’re quite nice. Not harsh at all.

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maxl96
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YuvalS wrote:

And easier to understand using lumen to Amper  to lumen 

 

Can someone explain this graph to me?
I am struggling with it for 10 minutes now.

YuvalS
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maxl96 wrote:

YuvalS wrote:

And easier to understand using lumen to Amper  to lumen 

 

Can someone explain this graph to me?
I am struggling with it for 10 minutes now.



Sorry maxl96, I did a lot of mess in this graph 
Here is the correct set:
 

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dee-u
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YuvalS wrote:

the answer is in Lumen to Amper  graph


And easier to understand using lumen to Amper  to lumen 

This data is for XM-L2 but all leds have similar behavior

1. Obviously the beter lumen to amp ratio the more efficient the led so first step to increase efficiency is by choosing best emitter with lumen to amp (or lumen to watt) ratio   
2. As you can see it starts linear. ie constant lumen to amp ratio – it called “linear section” and for this range of amps the LED is more efficient so you want to keep your light in this range
Your question is for 200 lm so you can think that you are in the linear section but it is only true for constant current drivers.
PWM driver actually working in the highest current allowed by driver so far off the linear section so 2nd way to improve efficiency is using constant current driver
3. we now now that led is more efficient on lower currents so 3rd way to improve efficiency is to divide the same current among more LEDs instead of driving 1 led with 3amps fo 1000 lm, drive 3 leds with 700amp each and get tand get combined 1000 lumens output for only 2.1amp 


With regards to the 3rd, does it mean those flashlights with more than 1 led/emitter are more efficient compared to single emitter ones?