Will this battery work in my Nitecore flashlight?

It fits Nitecore i-Series flashlights that accept 21700 batteries, including the P20iX, P23i, and SRT7i. Check your flashlight's manual or battery compartment to confirm it takes a 21700 cell.

How do I charge this battery?

You can charge it in any lithium-ion battery charger that supports 21700 cells, or in a Nitecore flashlight with onboard charging if your model includes that feature. Follow the charger or flashlight instructions for proper charging procedure.

What does 'used' condition mean for battery performance?

A used cell has been charged and discharged some unknown number of times, so its remaining capacity and cycle life are less than a new battery. Lithium-ion cells lose capacity gradually over hundreds of cycles, so expect this one to hold less charge than it did when new.

Is it safe to use a used lithium-ion battery?

Inspect the outer wrapper for tears, dents, or exposed metal before installing. If the insulation is intact and the cell does not swell or heat excessively during charging, it should be safe to use. Discontinue use if you notice any damage or abnormal behavior.

How long will this battery last on a single charge?

Runtime depends on your flashlight model and brightness setting. High-output modes draw more current and drain the battery faster, while lower settings extend runtime. The 5500mAh capacity gives you the total charge available, but actual hours of use vary widely.

Nitecore NL2155HPi 5500mAh Rechargeable 21700 Battery for i Series (P20iX, P23i, SRT7i, and More) - Used

stainless steel
rechargeable

The 3-second version

5500mAh capacity extends runtime between charging sessions
20-amp continuous discharge supports high-output flashlight modes
Built-in circuit protection against overcharge and short circuits
Used condition with unknown cycle history
Only fits specific Nitecore i-Series models
Requires separate charger unless light supports onboard charging

Why it's on GiftsFeed

High-capacity 21700 lithium-ion cell built for demanding flashlights

Generic 21700 cells often lack the discharge headroom that high-output flashlights demand, forcing the light to throttle brightness or shut down under load. This cell supplies a sustained twenty amps, so modes that pull heavy current stay lit at their rated output instead of stepping down after a few seconds.

The higher milliamp-hour rating matters if you regularly drain the battery. An extra five hundred milliamp-hours can mean the difference between finishing a night hike on one charge or swapping cells halfway through. For occasional use the gain is academic, but for people who actually run these lights hard, the added capacity translates to fewer interruptions.

Good gift when

Owners of Nitecore i-Series lights who need a replacement or spare cell
People who run their flashlights in high-output modes regularly
Anyone wanting longer runtime than older 21700 cells provide

Skip it if This is a used cell with unknown remaining cycle life and possible cosmetic wear. If you need guaranteed full capacity or plan to rely on it in critical situations, buy new instead.

Specs

Capacity: 5500mAh
Continuous discharge current: 20A
Form factor: 21700
Chemistry: Lithium-ion
Rated cycle life: Over 500 full cycles
Condition: Used
Compatible models: Nitecore i-Series (P20iX, P23i, SRT7i, and others accepting 21700)

What's included

One NL2155HPi 21700 rechargeable battery (used)

If you're giving it

No sizing to guess

Ships as a loose battery with no retail packaging; used condition may show wear.

The details

This rechargeable lithium-ion cell replaces the battery in select Nitecore flashlights that accept 21700 form-factor power sources. Rated at 5500 milliamp-hours, it holds more charge than earlier cells in the same family, and its 20-amp continuous discharge rating supports lights that draw heavy current during high-output modes.

The cell fits i-Series flashlights from Nitecore that take 21700 batteries, including models like the P20iX, P23i, and SRT7i. If you own one of those lights and run it hard enough to drain the original cell often, this replacement offers longer intervals between charging stops.

Built-in protection circuitry monitors voltage to guard against overcharge, overdischarge, and short circuits. A pressure-relief valve vents internal pressure if the cell overheats. The steel shell at each end is nickel-plated to resist corrosion and improve conductivity, and a metallic film coating over the body resists scrapes during installation and removal.

Rated to survive more than five hundred complete charge-discharge cycles before capacity drops noticeably. You charge it in any compatible lithium-ion charger that handles 21700 cells, or in a flashlight that supports onboard charging for this battery format. The cell arrives partially charged and ready to install.

Because this is a used unit, expect some wear on the outer film and possibly a lower total cycle count remaining compared to a new cell. Inspect the wrapper for damage before first use, and do not install a cell with torn or missing insulation.

Keep spare cells in a non-conductive case to prevent the terminals from shorting against metal objects. Do not store fully charged cells in hot environments, and do not continue using a cell that swells, leaks, or grows unusually warm during charging.

Nitecore

Nitecore NL2155HPi 5500mAh Rechargeable 21700 Battery for i Series (P20iX, P23i, SRT7i, and More) - Used

Rechargeable power cell delivering 5500mAh and 20-amp continuous output for compatible Nitecore i-Series lights

$21.56$26.9520% offat nitecorestore.com

Quantity

Buy from Nitecore

Ships and sold by Nitecore. About this merchant

The 3-second version

5500mAh capacity extends runtime between charging sessions
20-amp continuous discharge supports high-output flashlight modes
Built-in circuit protection against overcharge and short circuits
Used condition with unknown cycle history
Only fits specific Nitecore i-Series models
Requires separate charger unless light supports onboard charging

Questions

Will this battery work in my Nitecore flashlight?: It fits Nitecore i-Series flashlights that accept 21700 batteries, including the P20iX, P23i, and SRT7i. Check your flashlight's manual or battery compartment to confirm it takes a 21700 cell.
How do I charge this battery?: You can charge it in any lithium-ion battery charger that supports 21700 cells, or in a Nitecore flashlight with onboard charging if your model includes that feature. Follow the charger or flashlight instructions for proper charging procedure.
What does 'used' condition mean for battery performance?: A used cell has been charged and discharged some unknown number of times, so its remaining capacity and cycle life are less than a new battery. Lithium-ion cells lose capacity gradually over hundreds of cycles, so expect this one to hold less charge than it did when new.
Is it safe to use a used lithium-ion battery?: Inspect the outer wrapper for tears, dents, or exposed metal before installing. If the insulation is intact and the cell does not swell or heat excessively during charging, it should be safe to use. Discontinue use if you notice any damage or abnormal behavior.
How long will this battery last on a single charge?: Runtime depends on your flashlight model and brightness setting. High-output modes draw more current and drain the battery faster, while lower settings extend runtime. The 5500mAh capacity gives you the total charge available, but actual hours of use vary widely.