Caving and urbex headlamp: how to choose

What the lamp has to do underground

In a cave there is no ambient light: everything you see, you light. The lamp must last for hours, withstand water and knocks, stay on your head without bothering you, and not die because of a tired battery. It also serves the app: Lidark’s visual tracking needs a minimum of light on the walls, as the guide to iPhone LiDAR scanning explains.

Lumens and throw: two different things

Lumens measure the total amount of light emitted. Throw (beam distance) depends on how that light is concentrated. A very diffuse 1,000-lumen lamp lights a nearby room; a 300-lumen lamp with a tight beam reaches further. To compare, look for values measured to the ANSI/PLATO FL1 standard, which many makers apply: output, beam distance, runtime.

To move through modest-sized galleries, a few hundred lumens is plenty. A moderately powerful lamp that lasts the whole trip beats a floodlight that burns out in an hour. Very large chambers, shafts and deep quarries justify more power and a beam that carries.

Beam pattern: spot, flood or mixed

A spot (narrow) beam sees far, a flood (wide) beam lights your step and the periphery, a mixed beam combines both. For walking underground, a close flood is comfortable and a spot is for picking out a junction or a shaft in the distance. Lamps with several modes or a dual beam offer both.

In mist, dust or steam, a wide light bounces part of the beam back into your eyes. A lamp worn lower, or offset from your line of sight, limits this backscatter glare.

Red light and night vision

Most quality headlamps offer a red mode. A dark-adapted eye is barely sensitive to red: this light lights a notebook, a map or a teammate’s face without destroying your eyes’ adaptation. It is the same logic as Lidark’s night vision mode, which turns the whole screen red. Use it for static tasks and keep white for moving.

Batteries and runtime

Four main families of power supply, each with trade-offs:

• Disposable AAA or AA cells (alkaline or lithium): easy to find and replace, but heavy for the same output; alkaline cells handle cold poorly.
• NiMH rechargeable cells in cell format: rechargeable, handy to swap in the field.
• Lithium-ion cells (18650, 21700): high energy, powerful lamps; recharge from a power bank or USB-C.
• Built-in battery or a battery pack at the back of the helmet: well balanced, but slower to replace.

Reading runtime without being fooled

The stated runtime is measured by the maker, often until the light falls to 10% of its initial output under the FL1 standard, on the lowest mode. Runtime at full power is much shorter. Plan a margin of at least half, carry spare cells or a spare battery, and keep maximum power for the passages that need it.

The rule of three lights

Underground, you carry three independent light sources, each with its own power supply: a main lamp, a backup lamp on separate cells, and a third, smaller one, ready to use. A lamp that fails or floods must not leave you in the dark. The iPhone’s torch does not count: it is useful for scanning, but it drains the battery you need for everything else.

Waterproofing, weight and regulated output

The IPX rating shows water resistance: IPX4 withstands splashes, IPX7 temporary immersion (up to 1 metre for 30 minutes), IPX8 deeper immersion under the maker’s conditions. For a wet or muddy cave, aim for IPX7 at least, and check that the charging-port cover closes properly.

A weight that is contained and well distributed prevents neck fatigue: a battery at the back beats a heavy lamp at the front. A regulated output keeps power steady until the battery is nearly empty, instead of fading gradually. A switch lock stops it turning on in the bag.

Helmet, mounting and care

Underground, the lamp is usually worn on a helmet: a headband alone slips with mud and sweat. Check that the mount holds when you lean over or crawl, that the tilt adjusts with one gloved hand, and that the cable of a remote battery does not snag. A climbing or caving helmet that meets the EN 12492 standard also protects your head.

After the trip, rinse the lamp in clean water, dry it, open the battery compartment to let it air, and recharge the batteries: a dirty or half-charged lamp always shows up at the worst moment.

Putting it all together

For a typical trip: a mixed-beam, waterproof headlamp with a red mode and regulated output; a simple backup headlamp; a small spare light; and spare cells or a power bank. Lidark replaces neither a guide, nor a rope, nor a prior reconnaissance, and no lamp replaces preparation. To put it into practice, read mapping a cave with an iPhone, find the other tips on the guides page, and drop your surveys into the free 3D viewer.

Frequently asked questions