About this replacement
NARWAL J1 / J2 Series — 14.4V Li-ion Replacement Battery (XNY4S2PB)
This 14.4V 5200mAh Li-ion battery replaces the original pack in the NARWAL J1, J2, YJCC001, and YJCC010 robotic vacuum cleaners. It matches the OEM voltage, capacity, and connector spec for a direct swap. When the factory cell degrades and the robot stops completing full cleaning cycles, this is the replacement.
- J1 and J2 platform compatibility: These models share the same 14.4V battery bay, connector pinout, and BMS communication protocol. The XNY4S2PB pack — also cross-referenced as C392-C1-4S2P, C392-C2-4S2P, and C392-B-4S2P — fits all variants without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the J1 platform. The BMS handshook with the robot's charge circuit on first connection, and overcurrent protection triggered correctly when suction load was artificially restricted — no false shutdowns under normal operating draw.
- Dock charging habit on the J1: Do not leave the J1 sitting on its dock indefinitely between uses. Continuous trickle charge accelerates capacity fade in Li-ion cells at this voltage. Charge to full, then remove from dock until the next scheduled clean.
Suction dropping before the battery indicator reaches low on the J1
The J1's motor draws significantly more current when the filter is partially blocked or the brush roll is tangled. That elevated draw causes voltage to sag across the cell before the battery management system logs a low-charge event — so the robot behaves like it's running out of power while the indicator still shows mid-range. This is a voltage sag issue, not a capacity issue. Clean the filter and check the brush roll, then run a fresh cycle. If sag persists on a clean filter with a new battery, verify cell voltage at rest is at or above 16.0V post-charge.
Motor cuts out mid-run and then recovers after a few seconds
This is a BMS overcurrent trip, not a battery fault. When the J1's suction path is restricted — blocked intake, saturated filter, or tangled brush — motor current spikes past the pack's overcurrent threshold and the BMS disconnects the output. The robot pauses, the BMS resets, and it restarts. The fix is clearing the restriction, not replacing the battery. If the cutout happens on a clean, unobstructed robot, check that the replacement cell's BMS threshold matches OEM spec — the XNY4S2PB pack is rated to handle the J1's normal peak draw without tripping.