About this replacement
EXFO MAX-600 Series — 3.7V Li-Polymer Replacement Battery (GP-2147)
This 3.7V, 10000mAh Li-Polymer pack replaces the original battery in the EXFO MAX-600, MAX-605, MAX-610, and MAX-625 optical power meters and light source instruments. It matches the OEM cell dimensions (79.60 × 65.80 × 15.10mm) and the BMS profile the instrument firmware expects. Capacity figure is from the product specification sheet — 37Wh total.
- MAX-600 series platform fit: The MAX-600, MAX-605, MAX-610, and MAX-625 share the same battery bay geometry, connector pinout, and BMS communication protocol. One pack covers all four variants because EXFO standardised the power architecture across this instrument family.
- Bench tested on actual hardware: We cycled this pack under sustained optical source load and monitored the BMS handshake through charge and discharge. The protection circuit responded correctly to over-current at probe initialisation and held stable voltage through continuous measurement sessions.
- First-use calibration on the MAX-600: After installing the new pack, run a full calibration cycle through the instrument menu before field deployment. The MAX-600 maps battery state during calibration — skipping this step causes the low-battery warning to trigger early on the first measurement session, even with a full charge.
BMS lockout after the MAX-600 sat unused in a carry case for months
Li-Polymer cells self-discharge slowly in storage. If the pack drops below roughly 2.5V per cell, the BMS enters a protection lockout and the instrument will not power on — it draws nothing and shows no charging indicator. Recovery requires applying charge at a low pre-charge rate to bring the cell voltage back above the BMS wake threshold. Use the original EXFO charger or a lab supply set to 3.7V at 500mA and hold it connected for at least 30 minutes before attempting normal charging.
Voltage dropout causing readings to reset mid-logging session
During a long logging session, the optical source and detector run simultaneously, pulling sustained current that can expose any internal resistance in an aged or cold cell. A momentary voltage sag at that combined load trips the instrument's under-voltage protection, resetting the active log. This is not a firmware fault — it is the BMS responding to a real dropout. Check the battery voltage reading in the instrument diagnostics menu; anything below 3.5V under load confirms the pack needs replacement. A new pack at full charge holds above 3.6V through sustained dual-port draw.