ven
Flashaholic
Congrats, hopefully it should meet your requirements nicely. Reg fuel, loops are only 1.2v nominal and usually (presuming in this case with driver) it will be 3v-4.2v. So anything bellow will not power it . Not sure if the driver could be adapted, but then you could run the risk of running an 18650 too low(bellow 2.5v for example).
For emergency use, i would simply recommend another flashlight. Its always useful to have spare cell/s but even more use if a spare cell is in a light ready to go!. Not only does a spare light get you out of issues like flat cells, failures but also if the light is lost. So IMO a back up is pretty much a must...........you could get a standard c8 with xpl HI for $20 ish as a back up, or another maybe more compact light(for ease of carry) like the s2+ to name one for $15 ish.
For emergency use, i would simply recommend another flashlight. Its always useful to have spare cell/s but even more use if a spare cell is in a light ready to go!. Not only does a spare light get you out of issues like flat cells, failures but also if the light is lost. So IMO a back up is pretty much a must...........you could get a standard c8 with xpl HI for $20 ish as a back up, or another maybe more compact light(for ease of carry) like the s2+ to name one for $15 ish.