Not having a dig at anybody but if anyone wants to learn about 18650 batteries, chargers & lights have a look on Candle Power forums http://www.candlepowerforums.com/vb/forum.php
In particular this sticky thread http://www.candlepowerforums.com/vb/showthread.php?400136-Disassembly-of-some-UltraFire-batteries
And this sticky thread http://www.candlepowerforums.com/vb...!!-Misleading-budget-battery-and-lumen-claims
Basically the cheap chinese cree head lamp set ups are way overrated both in terms of battery power & led lumens brightness.
A single xm-l-t6 led has a theoretical max lumen output of about 1,000 lumens but in reality that figure is not achievable.
Even with the very best electrics, reflector & lens there is a loss as it is impossible to get 100% efficiency.
In the real world (not the chinese over inflated hyped up claims world) the max brightness a top end manufacturer such as Nitecore, Fenix, Olight, Armytek, Zebralight etc will claim from a single xm-l-t6 will be about 900 lumens & that is from an expensive unit with top notch electronics as there is a 10% efficiency loss even with the best electronics.
Even this figure will normally be incorrect as the real lumens, what is called OTF or "out the front" ie out of the front of the lamp will be lower as there will be a further loss of lumens caused by the reflector & lens.
Don"t get me wrong, cheap chinese cree lamps are bright (I have lots of them) but a single xm-l-t6 lamp will probably be around 500 lumens if you are lucky, which however is still really bright.
There is a reason the chinese cree lamps are cheap & it is because the build quality, electronics & components are cheap.
You still get a bright lamp for the money but accept that you will not get the longevity of life of a top end lamp.
I have fenix lamps that are still going strong after nearly 10 years use but do not expect any of the cheap chinese ones to last a fraction of that time.
However, & this is the reason I buy the chinese lamps, is that they are cheap enough to be disposable.
You can buy a pair of them for around £12 delivered, carry one as a spare & just accept that they won"t last for ever.
Perhaps more important are the batteries & chargers as the cheap chinese ones can be dangerous !
Batteries & chargers is somewhere I would not consider going cheap on as you don"t want an 18650 cell exploding while attached to your head !