Having seen a couple of Petzl headlamp reviews of late, just a reminder that Petzl have advised that lithium batteries should not be used with some of their headlamps.
The Myo XP is clearly listed in the "don't use lithiums" list on that Petzl page.
That said, I've ignored it with my Tikka XP for a year or more and it's still working fine - I like the weight saving and cold weather performance of lithiums, and I figure that if I knacker it at some point well never mind, LED technology is marching ever-onwards and there'll be something better out to replace it with.
But for peace of mind, Princeton Tec is the way to go....!!
My feelings exactly. My Petzl Tactikka has run on lithium AAA batteries since I got bored of trying to recharge NiMh ones. It seems fine, and once it goes to that great junkshop in the sky, its replacement will probably have brighter LEDs and a current regulator.
