Runtime Questions

[jtivat]

OK, so a KL1 will run for 1.5 hours at 16 lumens on one 123 and run for 4 hours at 17 lumens on two 123's. Also a N2 is 105 lumens with three 123's for one hour and a MN20 is 250 lumens for one hour on six 123's. What am I missing this does not seem to add up. Could someone please explain how this all adds up?

 

[Deleted member 684]

assumption number 1. 123 cells are of 1200 mah capacity. From there we can work out lumens/watt

3 volts x 1.2 ah = 3.6 watts

At best, each battery will provide 3.6 watt hour. Working with this "at best" assumption....

KL1 with 1 CR123 = 6.6 lumens/watt
KL1 with 2 CR123 = 9.4 lumens/watt
N2 = 9.72 lumens/watt
MN20 = 11.57 lumens/watt

Note that calculations were done at best case scenario

I don't know what you mean by how all these adds up. But this is what I think you want?

 

[jtivat]

What I am trying to say (I think) is that the N2 draws from three 123's so that’s 3600 mah. Now the MN20 draws from six that’s 7200 mah. Now the N2 at 105 lumens drains 3600 mah in one hour and the mn20 250 lumen drains 7200 mah in one hour that’s twice the capacity at more than twice the output so is the MN20 just a more efficient lamp or is there something I am missing.

 

[Bushman]

JT mabey it has something to do with the serial/parallel set up of the six cells in the m6?

I don't know, I'm just asking like the rest of ya!

 

[Brock]

The higher wattage halogen lamps tend to be higher in efficiency. Although not that much higher. It is a very curious thing to think about. I am betting it has to do with how much heat is lost to the load on the batteries combined with a more efficient lamp. That’s my guess anyway.