About this replacement
EXFO AXS-100 / AXS-110 OTDR — 3.7V Li-ion Replacement Battery (XW-EX003)
This 3.7V 1800mAh Li-ion battery replaces the EXFO XW-EX003 (also cross-referenced as GP-1001 and CGA-E/111GAE). It fits the AXS-100 and AXS-110 OTDR, as well as the FVA-600 and FPM-600 optical power meter series. The pack measures 53.00 × 35.30 × 11.00mm and seats flush in the original battery bay.
- AXS-100, AXS-110 OTDR, FVA-600, FPM-600 compatibility: These models share the same 3.7V single-cell Li-ion architecture, physical footprint, and connector pinout. The BMS handshake protocol is identical across the range, so the pack communicates state-of-charge correctly in each instrument without firmware intervention.
- Bench tested on actual hardware: We cycled this pack through the AXS-100 under sustained optical launch and receive load. The BMS held the 2.75V low-cell cutoff cleanly and returned a full charge curve without triggering a fault state.
- Post-installation calibration cycle: After fitting this pack, run a full calibration sequence through the instrument menu before field deployment. The AXS-100 maps battery state during calibration — skipping this step causes the low-battery indicator to fire early on the first measurement session, which can interrupt an active OTDR trace.
BMS lockout on the AXS-100 after the pack sat unused in a carry case
Li-ion cells in low-drain instruments self-discharge slowly over months. If the pack drops below approximately 2.5V per cell, the BMS enters a protection lockout and refuses both charge and load connections. The instrument will show no battery icon and will not power on from the charger. To recover the pack, apply a gentle pre-charge at 0.1C through a compatible charger until the cell voltage climbs above 3.0V — at that point the BMS releases and normal charging resumes.
OTDR trace resets mid-run with a battery showing partial charge
This symptom is not a low-charge event — it is a voltage sag. When the AXS-100 fires its laser source and simultaneously drives the display backlight and processor, instantaneous current draw spikes sharply. An aged or cold cell cannot sustain the voltage rail through that spike, and the instrument resets to protect its logic board. Check cell voltage under load rather than open-circuit — a cell reading 3.6V at rest can sag below 3.2V the moment the laser fires. Replace the pack if loaded voltage drops more than 0.4V from the resting value.