EXFO MAX-710B Compatible Battery 3.7V 10950mAh Li-Polymer

EXFO MAX-710B Series — 3.7V Li-Polymer Replacement Battery (XW-E413)

This 3.7V 10950mAh Li-Polymer pack replaces the original battery in the EXFO MAX-710B optical power meter and light source family, including the MAX-710B-M1, MAX-710B-M1-E1, and MAX-715B. It also cross-references OEM part numbers XW-E418 and XW-EX413. Capacity is rated at 40.52Wh — matched to the original specification.

• MAX-710B platform fit: The MAX-710B series shares a common battery bay and connector across its variants. The BMS handshake on these units communicates over the same voltage rail, so one pack covers the full model range listed without modification.
• Bench tested on actual hardware: We cycled this pack through the MAX-710B power-up sequence, including light source activation and optical power measurement under sustained load. The BMS held within spec across the draw spike at module initialisation and did not trip cutoff during continuous logging.
• Field calibration before first deployment: After installing this pack, run a full calibration cycle through the instrument menu before heading out. The MAX-710B maps battery state during calibration — skip it and the instrument will throw premature low-battery warnings mid-session, even with a full charge.

BMS lockout after the MAX-710B sat unused in a carry case for months

Li-Polymer cells self-discharge slowly during storage. If the pack drops below approximately 2.5V per cell, the BMS enters a protective lockout state and the instrument will not power on or accept a charge. This is not a dead pack — it is a protection circuit doing its job. Connecting the instrument to its charger for 15–30 minutes at a low-current trickle is usually enough to bring the cell voltage above the recovery threshold and re-initialise the BMS. If the charger LED does not respond at all, try a different USB-C or dock charger rated to the unit's input spec before concluding the pack is unrecoverable.

Readings drifting or resetting mid-session during a logging run

This happens when sustained sensor load pulls cell voltage low enough to cause a brief dropout — not a full shutdown, but enough to interrupt the measurement circuit. The root cause is usually a degraded original cell that can no longer hold voltage under the combined draw of the light source and logging processor. A fresh pack with full capacity eliminates the sag. After fitting this replacement, verify cell voltage is sitting above 3.6V under load using the instrument's battery status screen before starting a long logging session.