Direct-to-airflow design
The second objective is to create an effective thermal pathway for heat to go from the LED chip to the outside air to be extracted.
A lot of cheaper lights will use an extrusion with standoffs for the board to sit on, and sometimes don’t even have material behind the LED chip itself to pull heat away. This results in a light quickly overheating even when in motion.
High quality lights will have a direct thermal pathway, although admittedly this is very hard to determine unless you have a light torn down in front of you.
Magnesium & Thermodynamics
One of the other items that sets Outbound apart from typical light manufactures is our focus on magnesium as our heat sinking material.
Magnesium is an extremely lightweight metal that has good thermal properties. However when a lot of engineers look at a material suitable for heat sinks they gravitate straight to aluminum due to the fact the thermal conductivity is 33% higher than magnesium (96 W/mK vs 70 W/mK for diecast applications). Though thermal conductivity is only part of the thermal equation.
When we look at heat rejection for a lamp, we often are considering it moving within an air stream which means that the thermal bottleneck is not going to be how fast heat moves through a material (thermal conductivity) but rather how fast we can remove the heat via convection.
The only time that the rate of heat removal via convection in an air stream outpaces how fast the heat moves through the material is at extremely high speeds with forced direct airflow. Speeds that no biker will ever hit. So instead of focusing on the thermal conductivity of a material, we’ll focus on improving the weight of the light and increasing the surface area. This is why all our lights use magnesium die casting with diecast bodies that feature finned surfaces. We get the benefit of an extremely light body, a lot of surface area, and improved thermal characteristics.