14.4V 2600mAh Li-ion 18650 4S1P Compatible Battery Pack

Custom Battery Packs 18650 4S1P — 14.4V Li-ion Replacement Battery

This is a 14.4V, 2600mAh (37.44Wh) lithium-ion replacement pack built in a 4S1P configuration using 18650 cells. It suits devices that draw from a 14.4V Li-ion power source where the original pack has lost capacity or stopped holding charge. The pack measures 132.00 × 36.90 × 20.00mm — confirm those dimensions match your application before ordering.

• 4S1P cell arrangement: Four 18650 cells wired in series deliver a nominal 14.4V rail. A single parallel group means capacity is determined entirely by the individual cell rating — 2600mAh per cell, 2600mAh total. Devices calibrated to this voltage range accept the pack without voltage-mismatch errors.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on the bench. The onboard BMS held cell balancing within spec across all four series cells and triggered protection cutoff correctly at low-voltage threshold. No cell drift was detected across the first three cycles.
• First-cycle calibration tip: If your device has an integrated fuel gauge or capacity indicator, run one complete charge-to-discharge cycle after installation. The gauge calibrates against the new cells during that first full cycle — skipping it can cause the indicator to read inaccurately for weeks.

Pack running at lower voltage than rated on first use

18650 cells ship at storage voltage — typically 3.6–3.7V per cell, which puts a 4S pack at around 14.4–14.8V rather than the full 16.8V you'd see after a complete charge. This is normal. It is not a defect. Charge the pack fully before first use and recheck voltage at the terminals — a healthy pack will read 16.7–16.8V at full charge. If voltage stays low after a full charge cycle, check the charger output, not the pack.

Device rejects pack immediately after swap

Some devices run a voltage range check or BMS handshake on power-up before accepting a new pack. If the pack shipped at storage voltage, it can fall just outside the device's acceptance window. Charge the pack fully via a compatible 14.4V Li-ion charger first, then re-insert it — most devices clear the rejection after the pack voltage sits above the detection threshold. If rejection persists, power-cycle the device with the pack seated and try again.