Although I have plenty of lights to choose from for when I am working outdoors on my nightshifts I tend to favour my Convoy C8 for outdoor work and my BLF A6 for general in and outside work. The A6 tends to run out of power before the end of the night and that means a battery change.
I am one of those people that for at least 70% wants a light on full power but that does not need to be 1200 Lumens. I would guess 700 - 900 would be fine especially as I hate stepdown as they always seems to step down at inappropriate times.
So basically which S3 blends the best power vs runtime in high power mode? Tint is not mega important as seeing things clearly is more important than the colour of the beam.
That would give you useable light, but would be best suited for close use, and would not have any “wow” factor if you need bright illumination. My typical EDC is a 14500-powered TrustFire F20, driven at ~1.4A. It works well for my normal needs, but if I go outside at night I usually grab a more powerful light.
Based on Match’s chart here:
…I’d suggest going with the 6x 7135 driver which should give you the 700 lumens you wish, but at the expense of runtime.
Typical assuage would be to have the light on full power for between 20 and 40 minutes about 3 or 4 times per night and to have it on medium power for about 40 minutes and then again for about 20 minutes. A fair bit of it is for checking that windows are secure in buildings that are say a hundred foot away and up to three stories tall. The Convoy C8 is great for the exterior for when I need to check on playing fields and some park land but not so ideal for lugging around building checks. The brighter the torch the further away I can afford to be from what I am looking at which saves me time and energy but running out of power is a pain so I don’t mind dropping some high end power for a longer run time.
I think you will have a hard time getting the amount of light you want for the length of time you want from a single-cell 18650 light. Again, per Match’s chart:
A 1A (3x 7135) driven XM-L2 will give you ~450-500 lumens on high. From an S3, it would be a fairly floody light without much reach. A very-high capacity 18650: http://www.mtnelectronics.com/index.php?route=product/product&path=59_88&product_id=561
…would give you a theoretical 3.5 hours of runtime. As an alternative, you might wish to keep a second cell charged and with the light rather than to sacrifice brightness. Example, this holster has a sleeve for a second cell on the side… http://www.mtnelectronics.com/index.php?route=product/product&path=25_73&product_id=103
I am coming to the conclusion that the savings made from the drop in power when it comes to battery life don’t translate to a good enough return. Maybe I will just have to live with lugging an extra battery around with me. This is fine this time of year but come the summer I like to carry as little as possible. I would send off for that holster in a heartbeat by the way sadly it is quite expensive postage from the US to the UK.
What I’d do is build one with a Nichia 219C. It’s a little more throwy than the XM-L2/XP-L and has a super-flat discharge curve. I’d remove a couple 7135s for a 2.2A driver.
Now I know what you’re thinking. That’s under 700 lumens out the front and it’s going to look half as bright as the A6, but that’s not actually how it works. Human perception of brightness is logarithmic. You need about four times as much light for it to seem twice as bright. Also, since the 219C has a smaller emitter surface than the XM-L2/XP-L, the hotspot will be more intense, and the beam will throw as far with a lot less total output. I got an intensity increase of about 80% (measured with a phone light meter - more accurate than eyes, but less accurate than a dedicated light meter) going from an XM-L2 to a 219C in a Roche F8.
Here are some beamshots and runtime graphs with the 219C. Note that I used a laptop pull with low capacity for the runtime graphs (the same one for each graph, to be fair to all emitters), so you’ll get a lot more out of something like an MJ1 or NCR18650B.
Edit: the Convoy M1 would be a good compromise between the size of the A6/S3 and the C8. I use the similarly-configured F8 with a 219B all the time.