CustomDUO modules

Fitting CustomDUO Modules 

CustomDUO LED upgrade modules will work with all variants of the original pre 2018 Petzl Duo. Modules are not available for the new 2018 DuoZ and DuoS, which are factory sealed and not designed to be upgradeable in the future as LED technology advances.  The original Duo continues to be a lamp of choice for cavers across the world, due to its upgradeability and other qualities extremely well suited to the demands of caving.   

Module fitting - v42 and Simple 

Prior to fitting it is of course necessary to remove original reflector, bulbs, LED modules, etc. Unscrewing the grey bezel in order to remove the front window can sometimes prove challenging if Duo has been left to rot, but inevitably they do come off. (Hint, if you can't do it then find someone with strong hands. The trick is to squeeze and turn at the same time !!!)


CustomDUO Omni modules are a simple push fit into the Petzl Duo lamp housing. Electronic connection is via the 2 pins on reverse of module which locate in the Duo bi-pin bulb / LED connection socket. Orientate Omni module in the body of your Duo, aligning the contact pins, and push fit module into place. Ensure the module is sat down fully in Duo body. Test operation of module. If module does not work immediately, then read about battery polarity below.


To conclude, refit the Duo front window. Some silicone grease on the seal and threads is always a good idea. Holding window in position with thumb, refit the grey plastic bezel until the Petzl correct fitting alignment marks (on top of the lamp) are correctly orientated. The marker formed on the grey screw bezel should be somewhere in between the two markers formed on the top of the yellow lamp body. 


Very occasionally we come across an early (pre 2004) Petzl Duo which has been wired up back to front, and the polarity is wrong for the Customduo LED modules. This affected some, but not all early Duos, and these Duos are now extremely rare. Polarity conscious LEDs hadn't been considered at this time so it wasn't important which way around the positive and negative were wired at manufacture. If you fit your CustomDUO module and it does not immediately work, chances are that your Duo is wired up back to front. The solution is simple. Reverse the polarity of the batteries in the holder, i.e. positive to negative, and vice versa. The module will then work. CustomDUO modules are polarity protected, so you will not have damaged the module by finding this out. If this does not work then please contact us. There is invariably a solution.



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 (omni) module, i.e. 700mA flood and 700mA spot, 1400mA combined, may not be achievable dependant on battery type (NiMh or Alkaline), battery quality and 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 same applies to the Simple (r01) which uses a high setting at 1000mA. The slight upside of this is that reduced power draw from batteries by default will result in extended operating durations. 

In our opinion, 1400mA is at the limit of what can be realistically achieved with Petzl Duo and the best AA cells, given the battery technology currently available. For best result we suggest low self discharge NiMh batteries, such as the 'Eneloop' brand. 


The regulated power settings levels for modules are given in mA. To determine the approximate regulated duration of light on your battery arrangement at a given power setting, simply divide the mAh capacity of your cell pack by the mA power draw at a given setting. For example, using 2100mAh NiMh low self discharge AA batteries at a power setting of 350mA will give a regulated duration in the region of 5-6 hours.


The original Petzl Duo modu'led 14 (14 LED module) offered light output of less than 70 lumens, at approx. 0.35 Amp (6 hours on set of AAs). Using the latest high power LEDs, CustomDUO modules can provide approx 170 lumens at this power level,  or a similar 70 lumen light output at around 0.15 Amp (16 hours on set of AAs).


We are occasionally asked if it is possible to run CustomDUO modules from Li-ion battery packs typically constructed from 18650 cells. The modules will run very well at 3.7v, for example a single 3.7v li-ion battery or a number of cells parallel wired. The only small issue to note is that battery charge level indicators are set up for 4xAA batteries, so will not provide an accurate indication of battery charge level. Series wired cells, forming higher voltage packs, for example 7.4v are not suitable and will likely damage the modules (which are limited to 6 volt max). We are not convinced that this is the best idea ever, but it is possible to fit 2 x 18650 cells into a stripped out Duo box. It's very tight though, you have been warned.