CustomDUO modules 

Programming v42


The v42 can be easily configured to individual requirements, using the Customduo infrared remote control (requires CR2025 coin battery, not included). 


The v42 has 4 factory default light settings. This can be modified from 1 to 9 settings depending on user requirement.

 Moon mode and battery charge level indicator   


The v42 has a moon setting (main flood LED very low) for maximum run time, and battery charge level indication. Operating the switch very quickly, on-off-on ('double switch') will turn on moon mode. This low level light is well suited to underground camp, expedition, small passage caving, long prusiks and emergency. When moon mode is selected, the 5 green indicator LEDs main LED will show the level of battery charge, for a few seconds. The battery charge indicator can be user calibrated for standard 4xAA batteries or for 3.7v li-ion conversions of the Petzl Duo. 

Thermal management


The v42 incorporates thermal management in order to protect the module from over temperature operation. This may be significant if using high output setting for extended time periods. If the module is too hot, it will automatically step the power down to a lower level of light in order to protect the LED, and remain at this level until next switch operation.

v42 (r02) Operation 

Factory Setting

Spot LED

Flood LED


(5000k LEDs)


(3000k LEDs)


(est. 2500mAh eneloops)

1 (low flood)



73 lumen

65 lumen

16 hours

2 (high spot)



310 lumen

280 lumen

3 hours

3 (medium flood)



172 lumen

156 lumen

6 hours




620 lumen

560 lumen

1.5 hours




8 lumen

8 lumen

100 hours

* estimated light output at 85 degC dependant on capability of batteries used

The v42 (r02) has two main LEDs. A focused spot LED and a wide angle flood LED with optic. In normal operation, the v42 has four factory default power settings (see following table). To switch between the settings, use the down switch on the Petzl Duo. Switch on-off-on-off etc, to move between settings 1-2-3-4 ... 1-2-3 etc, in a looping sequence. Setting 1 will blink momentarily whenever selected to make it very easy to determine where you are in the sequence, and which setting has been selected. 






Cree XP-G3


Flood Off





Spot Off (0mA)


24 lumen

73 lumen (1)

172 lumen (3)

310 lumen

Spot (50mA)

24 lumen

48 lumen

97 lumen

196 lumen

334 lumen

Spot (150mA)

73 lumen

97 lumen

146 lumen

245 lumen

383 lumen

Spot (350mA)

172 lumen

196 lumen

245 lumen

344 lumen

482 lumen

Spot (700mA)

310 lumen (2)

334 lumen

383 lumen

482 lumen

620 lumen (4)

Batteries, power and light output 

As standard, the Petzl Duo uses 4xAA batteries (some use 4xC cells). It is important to note that the highest power settings of the v42 module, i.e. 700mA flood and 700mA spot, 1400mA combined, may not be achievable dependant on battery type (NiMh or Alkaline), battery quality / condition, and level of charge. Lamp condition is also a factor. If the batteries cannot deliver e.g. the 1400mA required, the lamp will operate as normal, but not at full brightness.


The v42 allows the light level provided by the spot and/or flood LEDs to be modified for each setting, to individual requirement. The spot and flood LEDs can be operated separately or blended together. Each LED can be operated at v.low (50mA), low (150mA), medium (350mA), and high (700mA), offering a choice from 24 possible light combinations, as per following table (settings 1-4 are the four factory default levels).