Be careful with the supplied battery !!!

First of all, the most important:
The supplied batteries are !!! NOT !!! protected against short circuit or undervoltage.
And although it is on the Kunstoffhülle so: "UltraFire 3800mAh ... Short-circuit and overcurrent protected".
I can not say whether this type always included / was but in my case this was so.

I just wanted time measure the capacity, as we know, more than real measurement results play a role in these indications the imagination in the batteries. I have the battery in my external charger is fully charged and then discharged individually with constant 1A. I was not really surprised when the voltage decreased significantly after only a quarter of an hour, but when the voltage significantly dropped by a further quarter of an hour below 2V, the protection circuit of the battery did not prevent a further deep discharge here. I have the trial canceled and looked at the battery more accurately.
Now to me the reason soon became clear: There was no circuit protection !!! It concerns with the supplied batteries are known as "Unprotected" cells, even though the envelope pretending otherwise.
Li-Po batteries can catch fire if mistreated (short circuit). A fire which can not be simply delete.
I was shocked. When I then found that the measured capacitance was only about 550mAh, came with me suspected that the misnomer on the cover probably was less an oversight, but rather an attempt by the manufacturer to dispose of its waste in this way and for it still to collect money.

But now to the actual headlamp.
At first glance, the process made a really good impression, but when I saw then that the cable just loosely through a hole in lamp head, I decided the lamp first time to decompose.
The control electronics is completely seated in the battery case, the lamp head cause only the two cables that are connected directly to LED. Temperature monitoring (reducing power when the LED to overheat threatens) is in any case impossible. Added to this is that the motherboard of the LED has a very small contact area with the lamp head, so that the heat dissipation functioning inadequately. Premature aging and an associated luminance loss is inevitable.
A cable strain relief is not really there, a couple of times too, the cable taut and the thin wires are from.
Note should also remember that the lamp can easily be turned on accidentally, for example when the power button is pushed briefly in the backpack. The lamp head can be very hot here. Here the lack of temperature monitoring makes them particularly noticeable.

Conclusion:
Please look at the Li-pos always first, or be tested by an expert.
When in doubt, the lamp without batteries buy (is also available) and the batteries separately order to or equal to the version with AA batteries.
The lamp I would recommend only to those who know what is important (be careful that the lamp head is not too hot) and possibly minor repairs can make yourself. The lamp is well detachable and can also be used as a platform for their own tests. But
Warning: Not suitable for the layman. With these batteries really dangerous.