21700 batteries
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Our selection
Samsung 50E 21700 (5000mAh)
$3.99
The benchmark high-capacity 21700 cell: the Samsung 50E offers 5000mAh in a compact format, ideal for powerful flashlights, scooters and DIY batteries.
- Format: 21700 (INR21700-50E)
- Capacity: 5000 mAh
- Continuous discharge: About 9.8A
- Nominal voltage: 3.6V (lithium-ion)
- 5000mAh, the best capacity/price ratio in 21700
The Samsung 50E cell (INR21700-50E) is a rechargeable lithium-ion cell in the 21700 format, renowned for its excellent capacity/price ratio. With its 5000mAh and a continuous discharge current of about 9.8A, it offers a very good balance between runtime and power. It is used in powerful flashlights, electric scooters and bikes, DIY battery packs and electronic mods. This is a bare, unprotected cell, reserved for experienced users.
Molicel P42A 21700 (4200mAh)
$8.99 $5.99
(11)
The 21700 sibling of the 18650 benchmark: 4200mAh and 45A continuous, built for cordless tools, ultra-powerful flashlights and demanding electronics.
- Format: 21700
- Capacity: 4200mAh
- Continuous discharge: 45A
- Nominal voltage: 3.6V (max 4.2V)
- 45A continuous, THE 21700 high-drain benchmark
The Molicel P42A is the 21700 version of the famed P26A, a Taiwanese high-drain lithium-ion cell trusted by flashlight and power tool enthusiasts. With 4200mAh and a 45A continuous discharge rating, it far outclasses generalist 21700 cells on instant power. Sold as a bare, unprotected Flat Top cell for experienced users.
We tested several P42A cells in a DIY power tool pack and a very demanding flashlight, and the verdict is clear: this cell handles high current without heating up or sagging in voltage, where a generalist high-capacity 21700 quickly shows its limits. The Flat Top format fits most cell holders and packs. Capacity (4200mAh) trails the best high-capacity cells on the market (up to 5000mAh), but under heavy load, real-world runtime feels better than with a cell that is not built for the job. One real caveat: it is a bare, unprotected cell, strictly for experienced users with a proper lithium charger and the usual safety precautions. For anyone who needs instant power in a 21700 format, it is a proven, trusted choice.
Klarus 21GT-50 5000mAh
$19.95 (4)
The 21GT-50 is Klarus's high-capacity 21700 battery: 5000mAh, 15A continuous discharge and a built-in protection circuit for the most demanding flashlights and devices.
- Capacity / Discharge: 5000mAh / 15A continuous
- Protection: Built-in circuit (overcharge, over-discharge, short circuit)
- Format: 21700 Button Top, 3.0in x 0.8in (75 x 21.5mm), 2.5oz (72g)
- Energy: 18Wh, 500+ cycles
- 5000mAh and 15A, Klarus's high-capacity cell
The Klarus 21GT-50 is a rechargeable lithium-ion battery in the 21700 format, designed by Klarus for its most powerful flashlights (XT21X Pro, G15) while staying compatible with most devices that take this size of interchangeable cell. With 5000mAh of capacity, a 15A continuous discharge current and a built-in protection circuit against overcharge, over-discharge and short circuit, it offers a generous energy reserve for tactical flashlights and current-hungry devices.
The 21GT-50 has done several outings in a Klarus XT21X Pro, and the pairing delivers on its promise: the 5000mAh rating translates into noticeably longer runtime than an 18650, without the 21700 format weighing the whole thing down too much. The 15A continuous discharge has plenty of headroom for the current spikes of very high-output flashlights, with no excess heat noted during our testing. The internal protection circuit cuts off cleanly at full charge (4.2V) and on low discharge (2.75V), a real comfort compared with a bare cell you have to monitor yourself. One honest gripe: at 2.5oz (72g) and 3.0in (75mm) long, it doesn't fit every 21700 housing on the market, with some older adapters or flashlights machined right to the limit. Like other flashlight brands, Klarus doesn't manufacture the lithium cell core in-house but fits its own circuit and quality control, a common practice with no bearing on the reliability we've seen. For a high-end Klarus flashlight or any current-hungry 21700 device, it's a safe bet.
Nitecore NL2160 21700 (6000mAh)
$26.95 (1)
The Nitecore NL2160 pushes the 21700 format to 6000 mAh: a record capacity to power demanding flashlights, packs and devices for longer.
- Capacity / Voltage: 6000 mAh / 3.6V (21.6Wh)
- Continuous discharge: 8A maximum
- Water resistance: IPX6
- Type: Protected Button Top (21700)
- 6000 mAh, one of the highest capacities on the market
The Nitecore NL2160 is a protected 21700 battery that reaches 6000 mAh, one of the highest capacities on the market for this format. Built for powerful flashlights and headlamps, it supports a continuous discharge of up to 8A and benefits from IPX6 water resistance, a genuine plus outdoors. Its built-in protection circuit (overcharge, over-discharge, short circuit) and pressure relief valve make it a reliable cell for intensive use.
We tested the NL2160 in a high-power search light, the kind of device that drains a battery in one evening: the runtime gain over a standard 4000 or 5000 mAh 21700 is noticeable straight away, almost an extra evening before recharging. The IPX6 rating also proved itself on an outing in the rain, without a shred of worry for the flashlight's electronics. One minor drawback: with no built-in USB port, you need an external 21700-compatible charger, and its slightly above-average diameter kept it from fitting into an older cell holder that was supposedly built for this format, so it's worth checking compatibility before buying. For anyone after the biggest protected 21700 capacity around right now, it's hard to beat.
Soshine 21700 3C (5000mAh)
$9.33
A safe bet in 21700 with a real edge: this Soshine 5000mAh cell packs built-in protection, for solid runtime without giving up on safety.
- Format: 21700 (INR21700, 3C)
- Capacity: 5000 mAh
- Continuous discharge: 3C, about 15A
- Protection: Built-in circuit (overcharge/short circuit)
- Protected 21700 cell, rare for this format
The Soshine 21700 (3C) cell is a rechargeable lithium-ion cell in the 21700 format, with a rare advantage for this format: a built-in protection circuit against overcharge, over-discharge and short circuit. With its 5000mAh (18.5Wh) and a continuous discharge of 3C (about 15A), it offers a good balance between runtime and safety. It is used in powerful flashlights, electric bikes and scooters, DIY battery packs and some portable tools. Its built-in protection makes it more approachable for users less experienced than with classic bare cells.
We tested this Soshine 21700 3C in a hiking flashlight and for a small DIY pack, and the first good surprise is the built-in protection: for anyone not used to handling bare cells, it is reassuring, the circuit cuts off on overcharge or over-discharge. On capacity, the stated 5000 mAh seems to hold up, with runtime close to what a Samsung 50E offers in the same use. First downside: the extra length from the protection (70.5 mm versus 70 mm bare) kept the cell from fitting a very compact flashlight designed for strictly sized bare 21700 cells, so it is worth checking compatibility before buying. Second downside, broader than this specific product: Soshine remains a low-profile brand in the US and Europe, with fewer Western user reviews and less structured after-sales support than Samsung or Panasonic. That said, the build quality feels solid, and the capacity-to-safety ratio is good. An honest protected 21700 cell, best reserved for devices that accept its slightly longer length.
Keeppower 21700 5000mAh
$22.06
A high-capacity 21700 cell from a brand known for its built-in protection circuits: the Keeppower 5000mAh targets powerful flashlights and DIY packs.
- Capacity: 5000 mAh (min. 4900 mAh)
- Protection: Built-in circuit (PCB)
- Discharge: Up to 10A continuous
- Cycles: Over 500
- High-capacity 21700 format, reliable built-in protection
The Keeppower 21700 5000mAh is a premium rechargeable lithium-ion cell, in the larger 21700 format (bigger and higher-capacity than the 18650). As with all its models, Keeppower selects a quality cell and adds a built-in protection circuit against overcharge, deep discharge, over-current and short-circuit. With 5000 mAh (4900 mAh minimum), 3.6 to 3.7V and continuous discharge up to 10A, over 500 cycles, it is a reliable choice for powerful flashlights, e-bikes and DIY packs.
We already knew Keeppower's reputation on the 18650 format, and the 21700 5000mAh cell does not disappoint. Tested in a high-end flashlight, it comfortably delivers on its rated capacity: the real-world figure matches the guaranteed 4900 mAh minimum, translating into noticeably longer runtime than a classic 18650 at the same settings. The built-in protection circuit remains the brand's strongest asset: it cuts cleanly on short-circuit or over-deep discharge, a real plus over a bare cell. In use on a current-hungry flashlight, it copes well under sustained load, without unusual heat. Two caveats: Keeppower remains a niche brand, hard to find outside specialist cell retailers, and the 21700 format means checking your battery holder's compatibility before buying (longer and wider than an 18650). For anyone after a protected, reliable 21700, it is a safe bet.
Xtar 21700 5000mAh
$15.90
The high-capacity 21700 cell that puts you at ease: 5000mAh, a built-in protection circuit and 10A continuous discharge, for demanding flashlights and tools.
- Capacity / Voltage: 5000mAh / 3.6V
- Protection: Built-in circuit (PCB)
- Continuous discharge: Up to 10A
- High 5000mAh capacity with built-in protection
The Xtar 21700 5000mAh is a protected rechargeable lithium-ion cell fitted with a built-in circuit (PCB) against overcharge, over-discharge and short-circuit. With a nominal voltage of 3.6V and up to 10A continuous discharge current, it strikes an excellent balance between runtime and safety. Button Top format, slightly longer (2.9 in / 74.5mm) than a bare 21700 due to the built-in protection circuit. Ideal for powerful flashlights, power tools and DIY packs that call for a protected cell rather than a bare one.
We dropped the Xtar 21700 5000mAh into a work-site flashlight and a DIY pack built for an electric bike, two demanding use cases for this cell. The rated capacity delivers, with noticeably longer runtime than a standard 18650, which makes sense given the larger format. The built-in protection circuit is the real selling point over a bare cell: it cuts power before overcharge or over-discharge, which is reassuring for everyday use without manually tracking voltage. The trade-off for that safety: at 2.9 in (74.5mm) the cell is longer than a bare 21700 (2.8 in / 70mm), and won't fit every device designed for unprotected cells, worth checking before buying. For anyone wanting a reliable, safe 21700 without stepping into bare cells reserved for experts, this is an excellent choice.
LG M50T 21700 (5000mAh)
$4.99
5000mAh in a compact 21700 format: the LG M50T targets maximum runtime for DIY packs, e-bikes and long-duration flashlights.
- Format: 21700 (INR21700-M50T)
- Capacity: 5000 mAh
- Continuous discharge: About 7.3A
- Nominal voltage: 3.63V (lithium-ion)
- 5000mAh in 21700, made by LG Energy Solution
The LG M50T (INR21700-M50T) is a lithium-ion cell in the 21700 format, larger than the classic 18650, reaching 5000mAh of capacity with a continuous discharge rating of about 7.3A. It is an excellent runtime/size compromise for DIY battery packs, e-bikes and e-scooters, very long-runtime flashlights and energy-hungry portable tools. Bare unprotected cell, for experienced users only. Also available in a Button Top (M50) version depending on the intended cell holder.
We built the M50T into a test pack for a folding e-bike, a typical use case for this high-capacity 21700 format. First finding: the 5000mAh rating holds up in real use, with noticeably better range than an equivalent pack in classic 18650 cells, using fewer cells thanks to the larger format. The continuous discharge current (around 7.3A) stays modest compared to power-oriented 21700 cells like the Molicel P42A: the M50T is clearly built for runtime, not current spikes. One honest caveat: this cell circulates under several closely related variants (M50, button-top M50T, flat-top M50LT) depending on batch and retailer, with slight differences in rated capacity (4850 to 5000mAh); it is worth double-checking the exact variant received before fitting it into a cell holder. Availability can also vary a lot between retailers, and at the time of writing it is temporarily out of stock even at our regular US source. For a pack where runtime is the priority, it remains an excellent choice in the 21700 format.
