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

When your flashlight runs at high output for extended periods, standard batteries drain fast and leave you cycling cells constantly. This 21700 rechargeable lithium-ion battery delivers 5500mAh of capacity alongside a continuous 20A discharge current, giving you the headroom to run demanding lights without cutoffs or dimming under load.

Designed specifically for Nitecore's i-Series flashlights—including the P20iX, P23i, and SRT7i—this cell fits any model in that lineup that accepts 21700 format batteries. The combination of high capacity and robust discharge performance means longer runtime between charges, even when you're using turbo modes or sustained high-output settings.

Protection circuitry lives inside the battery itself, monitoring for overcharge, over-discharge, and short circuits. A pressure relief valve adds a secondary safeguard against thermal events. Nickel-plated stainless steel protectors at each end resist impact, improve conductivity, and prevent oxidation at the contact points. The outer casing wears a metallic film coating that holds up to the friction of repeated installation and removal.

Rated for more than 500 full charge cycles, the battery maintains performance over years of regular use. You recharge it in compatible Nitecore chargers, then drop it back into your light when the previous cell runs low. No disposable primaries to landfill, and no degraded output as the cell ages past the first hundred cycles.

The 21700 format is larger than 18650 cells, so this battery will not fit lights designed for that smaller size. Verify your flashlight's specification sheet before ordering. For i-Series owners running lights hard enough to notice runtime limits, this cell offers the capacity and current delivery to match how you actually use the tool.