Dummy Petzl Core

Older (2019) Petzl Actik headlamps have (probably) a manufacturing defect which leaves a ~1mm gap between the "door" and the body. It is just enough for thin wires. 

Note: This will not work on new (2022) Actik and other new headlamps for they have different construction. If not sure try to put wires in (or you drill holes - not recommended).

From time to time there is a time I need to use my head lamp for long time on highest setting. The Core can do it for about one and a half hour. One can have more Cores or tape AAA batteries together to make changing easier. However it will still make the annoying blinking and drop to lower setting. This can be sometimes dangerous. Using a dummy battery pack, I can use much larger batteries like 18650 Li-ions (or in my case batteries from RC things).

Things needed:

• 2x M3 heat set inserts (recomend these)
• diode    ← probably not needed (see other notes)
• 2x M3 screws (recommended 1.5 cm or longer)
• 4x M3 nut
• heat shrink
• wire (1 mm fits)
• soldering iron

Print settings:

I printed body on side with supports enabled (see picture). 

The rest does not matter as long as it fits into the headlamp.

Assembly:

• put heat set inserts in place
• (solder diode to an end of one wire)
• solder connector of choice to battery side of wires
• create a small loop on headlamp ends of wires
• make knots on wires inside body to prevent accidental breaking of loops
• secure places where a short circuit is possible with heat shrink
• put those loops on screws
• secure them with nuts (do not tighten yet)
• screw both screws into inserts
• tighten nuts
• try out
• (glue the lid to the body the wires should pass through the two channels)
• put small pieces of heat shrink over on the wires to keep them together

Other notes:

The diode may not be needed for there is probably reverse polarity protection built into the headlamp. I am not sure, so I included diode.

With a higher voltage drop diode it should be possible to run from 5V power bank. Fresh AAA batteries can have 1.7V or more (3x1.7V = 5.1V). This is, howerver, open circuit voltage, it will drop “immediately” when under load, so it is not equal to 5.1V from power bank. This is where the diode comes in for it can have voltage drop of lets say 0.5V, which should lower the 5.1V from power bank. (Not all diodes have this high drop). Disadvantage is that the diode will lower the voltage even when powered from Li-ion. 

I HAVE NOT TESTED THIS, MAY DESTROY THE HEADLAMP. Although if you try please write a comment :).