Inova UR611 Replacement Battery 3.7V 2200mAh Li-ion

Inova UR611 / T4 (Old Style) — 3.7V Li-ion Replacement Battery (FLB-LIN-7)

This is a 3.7V, 2200mAh (8.14Wh) lithium-ion cell that replaces the factory battery in the Inova UR611 and T4 Old Style flashlights. The FLB-LIN-7 part number covers all three listed models — UR611, T4, and T4 Lights Old Style. If your light runs on the cylindrical 71mm cell format, this is the correct fit.

• UR611 and T4 Old Style platform: These models share the same 19.6mm diameter cell form factor and the same driver voltage range. The BMS handshake sits at the same cutoff threshold across all three variants, so one cell spec covers the whole group.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the UR611 driver board. The BMS triggered its low-voltage cutoff cleanly at the expected threshold, with no premature shutdowns or protection trips under steady draw.
• Single-cell replacement tip: The UR611 runs on one cell, so there is no multi-cell balancing concern here. What matters is not mixing a partially discharged old cell with a new one if you carry a spare — always start both cells from the same charge state before swapping in the field.

Flashlight driver stepping down output before the battery indicator reads low

The UR611 driver uses a brownout protection threshold that kicks in before the cell actually reaches its BMS cutoff. When cell voltage drops under sustained high-output draw, the driver steps down the output mode to protect the LED and driver circuit — not because the battery is empty, but because the instantaneous voltage sag triggers the protection threshold. This is expected behaviour, not a fault. If the light dims and then recovers slightly after sitting idle for a minute, the cell still has usable charge remaining at rest voltage. Drop to a lower output mode to continue using the remaining capacity.

Significantly shorter runtime on turbo mode compared to standard output

Turbo mode draws several times more current than standard output from the same 2200mAh cell. That higher draw rate lowers the effective capacity the cell can deliver before hitting the driver's cutoff voltage — this is a real electrochemical effect, not a defect. A cell that powers the light through many hours on standard mode may last a fraction of that on sustained turbo. If turbo runtime feels too short, check that the cell is fully charged to 4.2V before use and switch to a mid-output mode for extended sessions.