About this replacement
Abus FUSG50000 Series — 3V Alkaline Replacement Battery (760AB)
This is a 3V alkaline battery rated at 17000mAh (51Wh), built to the 760AB specification. It fits the Abus FUSG50000, FUSG50100, FUSG50101, and FU2986 wireless alarm systems. These units use this cell to power wireless sensors, detectors, and the panel's standby circuitry between mains cycles.
- FUSG50000 series compatibility: The FUSG50000, FUSG50100, and FUSG50101 share the same battery bay geometry and 3V power rail. The FU2986 uses the same 760AB cell for its wireless sensor interface board. One cell type covers all four models.
- Bench tested on actual hardware: We ran this cell through the panel's self-diagnostic cycle and confirmed the BMS accepted charge state without triggering a low-battery fault after a 48-hour float period.
- Post-install panel reset timing: Do not run a zone diagnostic immediately after fitting this cell. The panel's charge monitor needs 24–48 hours on float before it reports an accurate state. Running a test too early will return a false low-battery warning on the display.
Why the FUSG50000 panel reports low battery hours after a fresh cell is fitted
The FUSG50000 panel measures battery state through a voltage threshold, not a fuel-gauge IC. A new alkaline cell can sit slightly below the panel's acceptance threshold for the first several hours as internal resistance stabilises. The panel sees this as a low-voltage condition and logs a fault. After 24–48 hours on float, the cell's open-circuit voltage rises above the threshold and the fault clears automatically without any user action.
Siren not sounding during test cycle after battery swap
After a battery swap, the FUSG-series panel enforces a 30–60 second charge-stabilisation delay before enabling the siren output. If you trigger a test within that window, the panel arms internally but the siren circuit stays muted. This is normal behaviour, not a wiring fault. Wait at least 60 seconds after fitting the cell, then run the test — the siren will fire on a confirmed trigger above 2.8V on the cell output.