Klarus 18GT-36 3600mAh
(3 reviews)
The 18GT-36 is Klarus's own 18650 battery: 3600mAh, a built-in protection circuit and 7A continuous discharge, matched to the brand's flashlights and beyond.
Characteristics
- Capacity / Discharge: 3600mAh / 7A continuous
- Protection: Built-in circuit (overcharge, over-discharge, short circuit)
- Format: 18650 Button Top, 2.8in x 0.7in (70 x 18.6mm), 1.8oz (52g)
- Cycles: 500+ charges
- Klarus-matched cell for its flashlights, reliable day to day
Detailed overview: Klarus 18GT-36 3600mAh 18650 battery
The Klarus 18GT-36 is a rechargeable lithium-ion battery in the 18650 format, developed by Klarus to power its own flashlights while staying compatible with most devices on the market that take interchangeable cells. It packs a rated 3600mAh 18650 cell paired with a built-in protection circuit that handles overcharge, over-discharge and short circuit, a genuine step up from a bare cell.
Electrically, its nominal voltage is 3.6V, with a maximum charge voltage of 4.2V and a discharge cut-off around 2.5V, values printed directly on the cell for peace of mind. Continuous discharge current reaches 7A, plenty for powerful flashlights, and charging is recommended around 2A (up to 3A max depending on the charger). Klarus rates it for 500+ charge cycles and an operating range of 14 °F (-10 °C) to 140 °F (60 °C).
Supplied in Button Top format (a raised positive terminal), it drops straight into flashlights that require this shape, such as some models in Klarus's own XT range (XT11GT, XT12GT+), while working just as well in any 18650 device that accepts a protected cell slightly longer than a bare one. Its dimensions, 2.8in x 0.7in (70 x 18.6mm) for 1.8oz (52g), make it a safe bet for current-hungry flashlights, and the same cell works just as well in headlamps, work lights, camping gear or any other device built around a single protected 18650.
Worth noting, as with most flashlight brands (Fenix, Nitecore, Keeppower...): Klarus doesn't strictly manufacture its own lithium cell core, but sources a professional-grade 18650 core and adds its own protection circuit, labeling and in-house quality control, a standard industry practice that takes nothing away from the reliability of the finished product. For anyone who already owns a Klarus flashlight, or simply wants a reliable, well-matched protected 18650, the 18GT-36 is a consistent choice with no nasty surprises.
Our tester's review: Pierre Freysinger
We ran this 18GT-36 in a Klarus XT11GT Pro for several weeks of night outings, and it delivers on Klarus's claims: the rated 3600mAh translate into noticeably longer runtime than a generic 3000mAh 18650. The Button Top format drops straight into flashlights that require it, unlike some bare cells. The built-in protection circuit is reassuring day to day, no unusual heat even after repeated 2A charges on a multi-format charger. One honest gripe: like any protected cell, it's a touch longer than a bare 18650, worth checking if your flashlight is machined to the millimeter. Klarus, like most flashlight brands, doesn't manufacture its own lithium cell core but adds its own circuit and in-house quality control, a common practice that hasn't dented the reliability we've seen over time. If you already own a Klarus flashlight, it's the obvious consistent pick; for everyone else, a solid, well-matched protected 18650.
Frequently asked questions: Klarus 18GT-36 3600mAh 18650 battery
With a charger designed for 18650 lithium-ion cells, never a NiMH battery charger. Klarus recommends charging around 2A (3A maximum depending on the charger), with charge voltage capped at 4.2V.
In most cases yes, since it's a standard Button Top cell. It's specifically matched to Klarus flashlights like the XT11GT or XT12GT+, but fits any device that accepts a protected 18650, slightly longer than a bare cell.
The 18GT-36 has a built-in electronic circuit that automatically cuts off on overcharge, over-discharge or short circuit. A bare cell has none of these safeguards and requires a smart charger and careful handling.
Like most flashlight brands, Klarus doesn't produce the lithium cell core in-house, but sources professional-grade cells and adds its own protection circuit and quality control. This is standard industry practice and doesn't affect reliability.
Around 2 to 3 hours with a 2A charger, longer with a slower one. Klarus rates the cell for 500+ charge and discharge cycles before any noticeable capacity loss.
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Published on 05/09/2026