# Ceiling Bounce Lumens: 67 Lumens (One Month) vs. 154 Lumens (Two Weeks)



## LEDAdd1ct (Nov 12, 2017)

I will be powering a neutral, 80CRI Cree XM-L2 with either a 150mA or 350mA driver.

I've done the math, and at an estimated five hours of use per night in an emergency lighting scenario, 
my battery of two cells in series will net me somewhere around 67 lumens for one month or 154 lumens for two weeks,
again, at five hours per night in either scenario.

I already have the host, LED, cells, and both a 150mA and 350mA buck driver.

Which way would you go?

67 ceiling bounced lumens is enough for a bathroom, but, in my opinion, not really enough for a living room or kitchen.

One month of runtime does sound pretty darn cool; however, my guess is that if we don't have power for a whole month,
there are much, much larger issues to worry about.

Two weeks at 154 lumens is only half the time, but, it is more than twice as bright.
In the past, I have regretted going too dim and wished for more light. 

What do you guys think?

Which way would you go?

I'm learning towards 154 lumens for two weeks.


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## StarHalo (Nov 12, 2017)

It comes down to the number of people/area you're lighting for; if it's just you, 67 lumens over where you're sitting is fine, but once there are other people around you, or you're expecting to ambiently light a space you're moving around in, that 154 lumens will come in handy.


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## aginthelaw (Nov 12, 2017)

I’ve found at nightfall when I’m busiest I need the higher lumens and as I’m winding down I use less


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## LEDAdd1ct (Nov 12, 2017)

Thank you for your responses!

Is there anything more efficient around 3700K–4000K (power in vs. lumens out) at 80CRI than the XM-L2 T5 emitter?


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## ssanasisredna (Nov 14, 2017)

LEDAdd1ct said:


> Thank you for your responses!
> 
> Is there anything more efficient around 3700K–4000K (power in vs. lumens out) at 80CRI than the XM-L2 T5 emitter?



Two of them .... in parallel.

Seems like a waste though. Odds are you will forget to charge the battery, or someone leaves the light on, etc. etc. If you are serious about backup, then redundancy is what is important. Two lights, two sets of batteries, ways to charge them.


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## LEDAdd1ct (Nov 15, 2017)

—copy.

I can't find anything that pumps out more lumens at 80CRI than the XM-L2 T5.

This is going to be part of a series of three lanterns:

1) Lantern One

67 lumens 
Frosted/diffused globe

12 nights at five hours per night (most likely a lot less...this is good to light up a bathroom or to use before bed)


2) Lantern Two = This Lantern = Ceiling Bounce

154 lumens
Two weeks runtime at five hours per night 


3) Lantern Three

217 lumens
Ceiling bounce
20 nights runtime at five hours per night


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## LEDAdd1ct (Apr 29, 2018)

I received the finished 154 lumen XM-L2 T5 5D3 80 CRI ceiling bounce mod and it is amazing _and_ I am very happy I went with more lumens!


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