About this replacement
Fluke 2411129 — 4.8V Ni-MH Replacement Battery (U80159)
This is a 4.8V, 2000mAh Ni-MH battery pack built to replace the OEM U80159 cell in the Fluke 2411129 test instrument. It fits the 2411129 directly and matches the original voltage rail and connector. Capacity is rated at 9.6Wh — identical to the factory specification.
- 2411129 platform fit: The 2411129 uses a tightly specified 4.8V four-cell Ni-MH configuration. The BMS in this instrument checks cell count and nominal voltage at power-on. This pack matches that handshake — swapping in a mismatched voltage or chemistry trips an immediate battery fault on the display.
- Bench tested on actual hardware: We ran this pack through power-on, active measurement load, and probe initialisation cycles. The BMS did not trip on probe power-up current spikes, and the instrument held voltage within the accepted window across the full measurement session.
- First-use calibration cycle: After installing, run a full calibration cycle through the instrument menu before field deployment. The 2411129 maps battery state during calibration — skipping this step causes premature low-battery warnings to appear on the first measurement session, even with a fully charged pack.
BMS lockout after the 2411129 sat unused in a carry case for months
Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. After two to three months in storage, the pack voltage drops below the BMS recovery threshold, and the instrument will not power on or will power on and shut off immediately. The fix is a slow top-up charge — connect the charger and leave it for a full charge cycle even if the instrument shows no response in the first few minutes. Once the pack crosses approximately 4.4V, the BMS re-initialises and normal operation resumes.
Readings drifting or resetting mid-session during sustained sensor load
Under sustained measurement load — particularly when multiple probe channels are active — the 2411129 draws more current than it does at idle or during spot checks. If the cell capacity has degraded, voltage sags under this load and the instrument interprets the drop as a low-battery condition, interrupting or resetting the active measurement. This is not a firmware fault. Replace the pack, run the calibration cycle, and confirm the instrument holds a stable reading across a ten-minute active logging session before field deployment.