Frequently Asked Questions

Fewer than the box is selling you. Reading and tent use want 5 to 50 lumens; walking a familiar path wants 50 to 150; close work wants 150 to 300; a yard or garage wants 500 to 1,000. Only seeing something a hundred meters away genuinely needs four figures, and even there beam shape matters more than output.

It depends entirely on the model and it is the single most consequential thing to check. Lights built around a standard cell — 18650, 21700, 14500, 16340 — take a five-dollar replacement. Lights described as having a built-in or non-removable battery cannot be re-celled: Energizer states plainly that its Vision HD uses non-removable lithium-ion batteries.

Thermal step-down, and it is the design working rather than a fault. LEDs degrade when they overheat, so the driver reduces current once the body reaches a set temperature. NEBO publishes a 30-second turbo duration for the SLIM Mini 500 and Streamlight publishes a 35-second burst for the Wedge — those published durations are exactly what your light is doing.

The emitters can produce that output; almost no handheld can sustain it. Ten thousand lumens takes on the order of a hundred watts, and a large 21700 cell holds only around fifteen to seventeen watt-hours — before you consider whether the body could shed a hundred watts of heat, which it cannot. The claim describes a moment, not a mode.

Usually not. A budget Sofirn SC31 Pro publishes 2,000 lumens and so does a duty-grade Streamlight Stinger 2020 at several times the price. What the money buys is a published runtime beside that output, an IPX rating, a tested impact height, a usable warranty and consistency between units — real things, none of which is brightness.

Lumens measure the total light emitted in every direction; candela measures the intensity at the brightest point of the beam. That is why COAST publishes 352 meters of reach from 300 lumens while Streamlight publishes 165 meters from 500 — the first light concentrates its output rather than spreading it.

That the light has been tested for temporary immersion at one meter for thirty minutes. IPX4, by contrast, covers splashing only. The X means dust ingress was not formally rated, which is normal on flashlights. Anything described as 'water resistant' with no figure attached sits outside the standard entirely.

The numbers are dimensions in millimeters: an 18650 is 18mm by 65mm, a 21700 is 21mm by 70mm. The larger cell holds more energy and runs longer at the same output, at the cost of a thicker, heavier light. For a pocket light the 18650 is usually the better trade; for sustained high output or a work headlamp, the 21700.

Two to four hours for most lights from empty, and the biggest variable is the charger rather than the light. Sofirn publishes 2.5 hours for the SC31 Pro with a 2A adapter; Streamlight publishes 4 hours for the MicroStream USB. An old 0.5A computer USB port can roughly triple those figures.

Usually the cable, the power source or a dirty port rather than the battery. Try a known-good cable, use a wall adapter instead of a computer USB port, and clean the socket with a dry brush or wooden toothpick — never a metal pin. If the light has been somewhere cold, let it warm up: charge controllers refuse to charge lithium cells below freezing.

Many are, for a structural reason: the emitters, drivers and cells budget brands buy are the same commodity parts the expensive brands buy, and a direct-selling brand pays no retail margin. What you give up is documentation, batch consistency and a usable warranty. Prefer a brand that publishes a runtime figure — it is the most reliable proxy for whether anything was measured.

One that runs on ordinary alkaline cells, because those hold usable charge for years on a shelf and can be bought during the outage itself. NEBO publishes 2,000 lumens for 2.5 hours on nine AA cells for the Newton 2000; Streamlight publishes 50 lumens for 37 hours on the AA-powered Siege AA lantern, which also floats.

No. Lithium cells age fastest when held at full charge or left completely flat, so a light permanently on a charger loses capacity faster than one topped up and unplugged. Charge on a hard surface, unplug when the indicator shows complete, and top up stored lights twice a year — when the clocks change is an easy date to remember.

The manufacturer's published maximum output divided by the price the light is selling for at the moment the page was built, with the price timestamped. Both halves are stated on the page. Where no live price exists, the figure is left blank and the button reads 'Check price' — we never substitute an MSRP or a remembered number.

No, and we say so on every page. There is no lab here, no integrating sphere and no drawer of samples. What we do instead is compile the manufacturers' own published figures, cite them, pull the live price, and divide. Where somebody does measure these things with instruments, we point you at them.

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No, and the structure makes it difficult for them to. A ranking is computed from published output divided by live price, so position is arithmetic rather than judgment, and where we adjust an order by hand we name the attribute we adjusted for. Several pages here recommend lights we earn nothing from.

Email info@lumenandledger.com with the page and the figure you think is wrong. We check it against the manufacturer's published source and either correct the page or explain why the figure stands. Corrections are noted rather than made silently, and we would genuinely rather have them than not.