Sofirn SP40 Manual

The Sofirn SP40 is a powerful headlamp designed for home, EDC, or outdoor activities like camping, hiking, etc. It can be operated from a single 18650 Li-ion rechargeable battery. The switch controls the following functions: Low-Medium-High, hidden Turbo.

Sofirn SP40 Components


Mode Low Medium High Turbo
Luminous Flux 5lm 90lm 450lm 1200lm
Running Time 220h 15h 4h 10min 1h 50min
Beam Distance 11m 38m 85m 136m
Peak Intensity 29cd 357cd 1800cd 4620cd
Impact Resistance 1 meter (3.28 feet)
Water Resistance IPX7: 1 meter (3.28ft depth)

Notice: The above mentioned parameters are based on tests according to international flashlight testing standards (ANSI/NEMA FL1) using one 3400 mAh 18650 Li-ion battery in Sofirn’s laboratory. Results may vary with different battery or under different environmental conditions.


  • Working Voltage: 2.8V - 4.2V
  • Battery Options: One 18650 Li-ion battery
  • Dimension: 108mm (length) x 25mm (head diamter)
  • Weight: 63±1 gram (without battery)
  • Flashlight body: Aerospace grade 6061 grade aluminum alloy, CNC manufactured to Military Grade Specification type III hard-anodized anti-abrasive finish to get solid build body, anti-crash geometry, and better heat exchange.
  • Toughened mineral glass lens
  • IPX7 Waterproof (submersion up to a maximum depth of 1m underwater for up to 30 minutes)
  • Reverse polarity protection from improper battery installation
  • Mode memory: Brightness levels will be maintained, it turns on with the remembered mode (general modes except Turbo)
  • Advanced Temperature Regulation (ATR) technology: ATR will adjust the brightness level automatically when the driver temperature reaches 55°C to prevent overheating
  • Power Indicator: The LEd indicator on the switch blinks in green for 5 seconds if remaining battery power is over 30%. When the indicator turns to red, battery condition is below 30%. Flashing red light indicates low power: replace or recharge battery as soon as possible.


  • Operating for a long time in “High” mode will warm flashlight up. This is normal.
  • Do not stare directly into beam or point it directly into anyone’s face.

Battery Specifications

Battery Type Dimension & Quality Nominal Voltage Compatible
Li-ion battery
18650 x 1 3.7V Yes
Lithium battery CR123A x 2 3.0V Not compatible!

Battery installation: Unscrew the tailcap to insert one 18650 battery with the anode side (+) towards the head, and then screw tailcap back on. Both flat top and button top 18650 batteries are supported.

Sofirn SP40 Battery Installation

Operation Instructions

The switch controls all flashlight functions as follows:

  • Short click to turn on, another click to turn off.
  • While the light is on, hold the switch to cycle through modes: Low → Medium → High
  • Doubleclick to activate Turbo mode, one click to return to last mode.

UI Reference

When the light is Off:

Button Action
1C On
1H Cycle through modes: Low → Medium → High
2C Turbo

When the light is On:

Button Action
1C Off
1H Cycle through modes: Low → Medium → High
2C Turbo

When the light is in Lockout:

Button Action
1C Double flash
4C On

Additional Resources