NARWAL J3 Replacement Battery 14.4V 6800mAh BP4S2PPM5B

NARWAL J3 / J4 — 14.4V Li-ion Replacement Battery (BP4S2PPM5B)

This 14.4V 6800mAh lithium-ion battery replaces the original pack in the NARWAL J3 and J4 robotic vacuum cleaners. It matches the OEM voltage rail and BMS communication protocol required by both models. Capacity is 6800mAh (97.92Wh), sourced to the same cell specification as the factory pack.

• J3 and J4 shared platform: Both models run the same 14.4V motor bus and use an identical battery bay connector with BMS handshake. A single pack covers both units because the firmware on each reads the same cell authentication signal from the BP4S2PPM5B and BP4S2PPM5D part numbers.
• Bench tested on actual hardware: We ran this pack through the J3 cleaning cycle under full suction load. The BMS held voltage above the low-cell cutoff threshold during sustained motor draw, and the charge controller accepted the pack without error flags on a standard NARWAL dock.
• Dock charging habit for NARWAL robotic vacuums: Do not leave the J3 or J4 sitting on the dock continuously between cleaning sessions. NARWAL's trickle-charge dock keeps the pack at float voltage indefinitely, which accelerates capacity fade in Li-ion cells. Charge to full, then remove the unit from the dock until the next scheduled run.

Suction dropping before the battery indicator reaches low

This happens when the motor draws more current than rated due to a restricted airflow path — not because the cell is depleted. A partially blocked filter forces the motor to work harder, pulling amps that push the BMS toward its overcurrent threshold. The BMS responds by throttling output voltage to protect the cells, which the vacuum reads as low power rather than a blockage. Clean or replace the filter first before concluding the battery is at fault.

Motor cuts out mid-cycle then restarts after a few seconds

This is a BMS overcurrent trip, not a dead battery. When sustained suction restriction — usually a near-blocked filter or partial brush-roll jam — drives current above the pack's protection limit, the BMS disconnects the output and resets after a short recovery window. The unit powers back on because the cells themselves are fine. Clear the brush roll, inspect the filter, and confirm airflow is unrestricted; the cutout should not recur once draw returns to normal operating current.