About this replacement
Noyes W2003M — 14.4V Li-ion Replacement Battery (3900-05-001)
This is a 14.4V, 2600mAh Li-ion battery for the Noyes W2003M handheld fiber optic inspection probe. It replaces OEM part number 3900-05-001. The W2003M is a field inspection instrument used in telecommunications and network testing environments.
- W2003M platform compatibility: The W2003M draws power through a tightly controlled voltage rail that requires a pack matching the 14.4V nominal threshold and the correct BMS handshake. A mismatched BMS profile triggers an unrecognised-battery flag before the probe module even initialises.
- Bench tested on actual hardware: We cycled this pack through probe power-up sequences and sustained inspection loads. The BMS handled the initialisation current spike without tripping, and the pack held voltage within the instrument's accepted window throughout the logging session.
- Post-install calibration step: After fitting this pack, run a full calibration cycle through the W2003M instrument menu before field deployment. The instrument maps battery state during calibration — skipping it causes premature low-battery warnings on your first measurement session in the field.
BMS lockout after the W2003M pack sat unused in a carry case for months
Li-ion cells self-discharge during storage. If the W2003M pack drops below approximately 2.5V per cell, the BMS trips into a protective lockout state and the instrument shows no sign of life. Standard chargers do not deliver enough trickle current to wake a locked-out BMS from that state. You need a charger with a recovery or wake mode that applies a low-current pre-charge pulse — typically around 0.1C — to bring the pack above the BMS recovery threshold before normal charging can resume.
Voltage dropout causing readings to reset mid-logging session
During a sustained inspection session, the probe module and data-logging functions draw combined current that can push a worn or partially charged pack into a brief undervoltage dip. The W2003M interprets this dip as a low-battery event and resets the active session to protect measurement integrity. The fix is not a reboot — it is ensuring the pack starts the session at or above 15.8V (fully charged). Verify pack voltage with a multimeter at the contacts before site deployment.