Lumens vs. CRI in Blackout Lantern

More Lumens or More CRI?

  • Give me more lumens!

    Votes: 2 25.0%
  • Give me more CRI!

    Votes: 6 75.0%

  • Total voters
    8

LEDAdd1ct

Flashlight Enthusiast
Joined
Jul 4, 2007
Messages
3,557
Location
Hudson Valley
Technology has come a long way and we now have many choices.
I am always fascinated by blackout lights, flashlights/lanterns with crazy long runtimes.

Below is a chart comparing two LEDs at 150mA drive current:

image.png



The LED on the left will produce approximately 54 lumens at 95 CRI 7A2 tint while consuming 0.421 watts at about 3200K.
The LED on the right will produce approximately 87 lumens at an unspecified CRI 5C1 tint while consuming 0.411 watts at about 4000K.

Using four 3.2v LiFePO4 32650 cells at 5000mAh capacity (which are sitting on the table in front of me) wired in 2S2P for 6.4V output, we get:

6.4V * 10mAh = 64 watt hours

64 watt hours / 0.421 watts = 152 hours runtime

Either of these two LEDs will allow for a very long runtime at 150mA drive current.

I already own the host and the batteries; the LED and driver are easy enough to acquire.



My questions:

1) For an emergency long runtime light/lantern, which one would you go with?

a) 54 lumens at 95 CRI and 3200K CCT at 7A2 tint

b) 87 lumens at (?) CRI and 4000K CCT at 5C1 tint


2) Would one would you choose?

a) Diffuser (i.e., a lantern)

b) Ceiling bounce


3) Do you think 54 high CRI or 87 unknown CRI lumens are enough for a long runtime light in a blackout?

a) Yes

b) No


4) Any other thoughts?


* * *

This lantern will happen. I just cannot decide between the two LEDs.

Part of me thinks a warm white/relaxing/high-CRI light is the way to go.

However, the other part of me thinks that at the end of the day, being able to see is the most important objective,
and 87 lumens will do a better job of doing that than 54 lumens.

Thank you!
 

Poppy

Flashaholic
Joined
Dec 20, 2012
Messages
8,359
Location
Northern New Jersey
Although I voted "give me more lumens" That was based on YOUR scenario.
Regarding MOST lanterns, I would want higher CRI, warmer lights.

BUT in this scenario, I believe that I would prefer a 5C1 tint over a 7A2 tint. IMO the 5C is a warm neutral, and that's comfortable, but the 7A2 tint is too warm.

If used indoors, where ceiling bouncing is an option, then I would prefer a flashlight.
Outdoors, then it would have to be a lantern.

Yes, 87 lumens ceiling bounced are enough for a room.
If you read through the first hundred posts of the power outage thread I think you'll agree that MOST people will be comfortable with about 100 lumens.

Many, if not most lanterns today go to about 300 lumens, IMo, that is about the max that any lantern should go to. Also most are cool white. Therefore, for most lanterns, I would prefer less lumens, and a warmer tint. I'd like a 100 lumen setting
 
Last edited:

LEDAdd1ct

Flashlight Enthusiast
Joined
Jul 4, 2007
Messages
3,557
Location
Hudson Valley
Thanks, Poopy. 5C has been my favorite neutral/4000K tint for a long time.

I may use just two cells of a much higher capacity for 199 hours flat output at 150mA drive current and 87 lumens, if I go with the 4000K XP-G3 S5 5C1.

Averaging five hours use per night, 199 hours / 5 hours per night = 39 nights.

Any blackout longer than that and light is the last thing I'd need to worry about!
 

Subterrestrial

Newly Enlightened
Joined
Jul 20, 2016
Messages
187
Location
The Mountains (they were calling....)
1) For an emergency long runtime light/lantern, which one would you go with?

b) 87 lumens at (?) CRI and 4000K CCT at 5C1 tint


More lumens is more important than tint in this situation IMHO. You want to be able to see enough to move around without running into or tripping over things, fumbling around in the dark, etc. Really, 4000k isn't that bad tint wise anyway. I have lanterns much higher than this. :whistle:


2) Would one would you choose?

a) Diffuser (i.e., a lantern)

As long as your globe is sufficiently diffuse and the tint is right, I think this is the best option for spreading your light around the area as you're working, preparing food, etc. Besides, if you're hanging it up near the ceiling, you should be getting some ceiling bounce anyway (I have a few ceiling hooks around the house to take advantage of this) and if the light isn't spreading around the room, I imagine it's small enough to carry around to different parts of the room if necessary.


3) Do you think 54 high CRI or 87 unknown CRI lumens are enough for a long runtime light in a blackout?

a) Yes

I would use at least two of the LiFePo4 cells you mentioned above.


4) Any other thoughts?

This is just personal preference but I like to have a warmer, much less brighter light to unwind before bed. If you can get a hold of another host, you might find both to be useful?
 

LEDAdd1ct

Flashlight Enthusiast
Joined
Jul 4, 2007
Messages
3,557
Location
Hudson Valley
The two builds are now shaping up like this:

1) Main Room Light: Roflan/Navy Battle Lantern Host ---> Ceiling Bounce Illumination

One 4000K XP-G3 5C1 S5 LED driven at 150mA for 87 lumens.

Two 40152 3.2V 15Ah LiFePO4 cells in series.

Figuring 6V * 14Ah = 84 watt hours

84 watt hours / 0.411 watts = 200 hours runtime

Proposed Uses:

Large rooms and family gatherings; meals and hanging out.

2) Take it With Me Smaller Lantern: Starlite Lantern Host ---> Frosted Globe Illumination

One 3200K XP-G2 7A2 95CRI LED driven at 150mA for 54 lumens

Four 32650 3.2V 5000mAh LiFePO4 cells in 2S2P configuration.

Figuring 6V * 10Ah = 60 watt hours

60 watt hours / 0.421 watts = 142 hours runtime

Proposed Uses:

Bathroom trips; smaller rooms; relaxing before bed.

Checklist:

—Roflan lantern (check)
—Starlite lantern (check)
—40152 cells (not yet) (need to confirm will fit inside Navy Battle Lantern prior to purchase)
—quantity four 32650 3.2V LiFePO4 cells (check)
—XP-G2 3200K Q5 7A2 95 CRI LED (not yet)
—XP-G3 4000K S2 5C1 LED (not yet)
—two 150mA drivers (not yet)
—ceiling for ceiling bounce (check)
—clear/frosted globe for Starlite lantern (not yet) (globe I have is blue)
 

LEDAdd1ct

Flashlight Enthusiast
Joined
Jul 4, 2007
Messages
3,557
Location
Hudson Valley
Me too!

It's too bad the majority of the modern lanterns are made like garbage. Need to modify existing stuff to have the solid build quality you want.

The Roflan lanterns are made to survive the apocalypse!

See here and here and here for details.
 

Poppy

Flashaholic
Joined
Dec 20, 2012
Messages
8,359
Location
Northern New Jersey
Me too!

It's too bad the majority of the modern lanterns are made like garbage. Need to modify existing stuff to have the solid build quality you want.

The Roflan lanterns are made to survive the apocalypse!

See here and here and here for details.
LOL
and they can be used as a kettle ball for exercise when you get bored! :)

Have fun building them :thumbsup:
 

angerdan

Enlightened
Joined
Feb 12, 2015
Messages
290
Location
Europe
My questions:

1) For an emergency long runtime light/lantern, which one would you go with?
b) 87 lumens at (?) CRI and 4000K CCT at 5C1 tint
4.000K is neutral white, can be used very universal.

2) Would one would you choose?
a) Diffuser (i.e., a lantern)
Easier to build than ceiling bounce


3) Do you think 54 high CRI or 87 unknown CRI lumens are enough for a long runtime light in a blackout?
Depends - for stationary yes, if you have a flashlight or other additional possibilities.
CRI above 85 is enough.


4) Any other thoughts?
Why build it yourself? How to dim the light, what about capacity display?

 

LEDAdd1ct

Flashlight Enthusiast
Joined
Jul 4, 2007
Messages
3,557
Location
Hudson Valley
I don't have the technical skill to build them myself, but, other folks on this forum do. :)

I believe the XP-G3 S5 5C1 has 70 CRI (minimum).

No dimming. 87 lumens for 200 hours = Perfection.

200 hours runtime = No need for capacity display.
 

LEDAdd1ct

Flashlight Enthusiast
Joined
Jul 4, 2007
Messages
3,557
Location
Hudson Valley
While researching which LiFePO4 battery to use, I sent the following email out.

I received express written consent to reproduce the reply.

I removed the name of the company and the links.

Relevant Portion of Email As Follows:

Hello! I have some questions about your 12V, 12Ah battery as depicted here:

*Link*


1) What voltage does the BMS terminate each cell at? What I mean is, I've read that a lot of BMS (plural) terminate at 3.65V or even 3.8V, drastically reducing the life of the individual cells which comprise the pack. I would like to know if the BMS could be set to terminate at 3.6V per cell?


We terminate with a single cell when 3.8V/cell is reached. Our cells have NO effect charging up to 3.8V which is not the case with other cells. Your information is not correct when using different lithium cells. We do not do custom BMS settings.



2) How do these units do sitting at full charge over prolonged periods of time? I am thinking of using one of these for an emergency light; it might go months between uses. I know lithium-ion cobalt 3.7V cells degrade when stored at full charge, i.e. 4.20V.

Phosphate cells reduce charge ~ 1% / month. Resting voltage is typically at 3.3V/cell after several weeks. However we can leave a charger ON at 14.6V with NO degradation of the cell. You are correct other cells and other cell chemistries stresses the cell and reduces the life if left on charger. That is NOT the case with our Phosphate cells.


-----END-----

My Questions for Fellow Flashlight Enthusiasts:

1) I read on the Internet that charging a LiFePO4 cell to 3.8V drastically reduces the number of cycles you get out of it, and that LiFePO4 cells should be terminated at 3.6V per cell.

a) Is this correct?

b) Is it possible this company has some sort of new LiFePO4 formula which makes this not the case?

2) The company claims you can leave the battery (and individual cells which are inside it) on the charger at full charge with zero degradation to the individual cell. I have never heard this before, and am surprised.

a) Is this possible?



Thank you! :)
 
Top