Anritsu PT01426 MT9090 Replacement Battery 4.8V 2500mAh

Anritsu MT9090 / MT9090A Series — 4.8V Ni-MH Replacement Battery (PT01426)

This is a 4.8V 2500mAh Ni-MH replacement battery for the Anritsu MT9090 and MT9090A microwave transmission analyzers. It also fits the 909815B and 909814B units and over 30 additional MT9090-series variants. The pack replaces OEM part numbers PT01426, G0202A, and PT01496.

• MT9090-series platform compatibility: All covered models share the same 4.8V four-cell Ni-MH architecture, connector pinout, and BMS communication protocol. The battery management circuitry handshakes identically across the MT9090, MT9090A, 909815B, and 909814B, so one pack covers the full instrument family.
• Bench tested on actual hardware: We cycled this pack on a live MT9090A, running full RF sweeps and transmission line measurements under load. The BMS maintained stable output through repeated probe-module wake cycles and did not trip on cold-start current draw.
• Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the MT9090 instrument menu before field deployment. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings on the first measurement session, even when the pack is fully charged.

MT9090 BMS lockout after the instrument sat unused in a carry case for months

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A pack stored for three or more months in a case can drop below the BMS recovery threshold — typically around 3.6V for a 4-cell pack — and the BMS enters a protective sleep state. The MT9090 will show no charging activity and may not power on at all. To recover the pack, apply a trickle charge at 100mA or less using a compatible external charger until cell voltage climbs above 4.0V, then transfer to the instrument for a normal charge cycle.

MT9090 shuts down mid-sweep with no low-battery warning

This failure is not a capacity problem — it is a voltage sag event. Under sustained RF sweep load, internal resistance in a degraded or cold pack causes a momentary voltage drop that the instrument interprets as a hard undervoltage fault, triggering an immediate shutdown before any warning can display. Ni-MH cells are particularly sensitive to this at low temperatures. Warm the instrument to above 10°C before starting a measurement session, and verify resting cell voltage is at or above 4.6V before deployment.