Is this normal for an Li-Ion?

[KentS]

The other day I was doing a combined bicycle commute home - runtime test for a Fenix P3D with 2 AW RCR 123 750mAh batteries (third time they were charged, 4.21V). According to some runtime tests I've seen I was expecting about 67 minutes on turbo. It was rather cold and moist, about 4 centigrades and my low battery indicator was set of after about 59 minutes (still 10 more minutes than I ever got with other Li-Ion batteries). After letting the flashlight rest and get warm indoors for an hour I tested again and got another 7 minutes on turbo. Is this normal? Was the shorter runtime a result of the cold temperature outside? Would I be able to get more runtime by sticking the flashligt in some sort of insulating cover? It just doesn't feel right as the problem is mostly the reversed - getting enough heatsinking.:thinking:

 

[shadowjk]

You could also test in room temperature whether just letting the batteries rest a few hours gives you a few more minutes of runtime...

 

[VidPro]

do the same test with the REST but not the temp change, all batts have some voltage draw down from hard loads for long times, even the mighty li-ion.
while some of it could be the temperature, lots of it was also the load. would you overheat your led for 10% more time? surely in any contained light there was at least SOME warmth from the emitting item adding warmth to the battery. almost every battery suffers from extreme temps at both ends, beings they are designed for operation in "room temperatures" li-ion and lithium suffer less than ni-?? and alkaline for sure, but they do indeed take a hit on total runtime. one should be happy that it was not alkaline and dead in the first 10% of the time not the last 90%