One of the most popular headlamp on the market, easy to mod and power source change - power per from standard 4xAA to a 8.4V battery pack. Since last year, it is my standard headlamp on AR races. With the 4x18650 Li-Ion battery pack (2s2p 7,2 V - 5200mAh / 37.44 Wh) gives me up to 11 hours at full power which in practice is enough for 48 hours adventure race.

Power consumption :

Power led - HIGH 3,3W / LOW 0,85W

5mm leds - HIGH 1,25W / LOW 0,1W

The lamp has a very good driver, so regardless of whether the power source you are using, light output is constant.

What do you need ?

1x Princeton Tec Apex or Apex PRO ;).

1x Cree XP-G emitter on micro mcpcb or star (then you will have to cut it to similar size).

Some thermal adhesive i.e. Arctic Alumina or other glue - I'm using 3M 467MP 0,05mm adhesive tape, some tin, soldering iron and screwdriver.

Modding !

Remove the two bolts on the top and carefully remove plastic cover – do not try open the head, there is still one more screw !

Remove the last screw :

Now, you are in , open the head and remove the collimator lens. – try not to leave your fingerprints there ;-).

Desolder the wires from the emitter :

Yes, I’ve already removed the thermal control diode between RT1 & RT2 pads – you don’t have to do it, but don’t cry if you break it . :)

Move the driver up, and remove old emitter, clean up the surface and glue there a new emitter in the center. You may use bigger mcpcb, but you will have to cut some plastic and will lost positioning pins for the collimator lens.

Put, the driver back and solder the wires, be careful to leave enough space for the collimator lens.

Screw everything together and her you have 250+ lumen Cree XP-G based Princeton Tec Apex !


How it light ?

On the left original Apex with the Luxeon III led, on the gith with the Cree XP-G R5 led



5000K vs 6200K

Cree XP-G are avaliable in many tint's (white shades), Below is a comparison between Outdoor White version (cosest to Neutral White - neutral white) 5000K and Cool White 6200K.

You can choose what you like :).