About this replacement
Fluke Microtest 2-Way Injector Tester — 9.6V Ni-MH Replacement Battery (2938-2003-01)
This is a 9.6V, 2000mAh Ni-MH replacement battery for the Fluke Microtest 2-Way Injector Tester, Microtest PentaScanner, and Microtest PentaScanner+. It slots directly into the handheld unit and restores field operation without replacing the instrument. Voltage and capacity match OEM part numbers 2938-2003-01 and 2938-2003-02.
- Microtest and PentaScanner fit group: These models share the same 9.6V Ni-MH pack, connector pinout, and BMS handshake protocol. The instrument polls the pack at startup for voltage confirmation, so a matched cell count and chemistry is required — substituting a different voltage pack triggers a fault state and blocks operation.
- Bench tested on actual hardware: We cycled this pack through three full charge-discharge passes on the Microtest platform. The BMS responded correctly at each charge termination point, and the instrument accepted the pack without fault codes across all cycles.
- First-use calibration on the Microtest: After installing the new pack, run a full calibration cycle through the instrument menu before taking it into the field. The Microtest maps battery state during calibration — skipping this step causes premature low-battery warnings during your first measurement session, even with a fully charged pack.
BMS lockout after the Microtest sat unused in a carry case for months
Ni-MH cells self-discharge continuously, even in storage. After several months in a case, pack voltage can drop below the BMS recovery threshold — typically around 8.0V for a 9.6V eight-cell pack. When the instrument attempts to initialise, the BMS detects undervoltage and locks out charge acceptance, so plugging in the charger appears to do nothing. The fix is to apply a low-rate conditioning charge using a Ni-MH compatible charger that supports a recovery or wake mode, bringing cell voltage up to at least 1.0V per cell before the BMS re-enables normal charging.
Instrument display showing erratic battery percentage at reboot after pack swap
The Microtest's battery indicator is calibrated to a voltage-discharge curve from the previous pack's cell history. A new pack resets that curve, and the display reads inconsistent percentages — often jumping from near-full to low warning within a short window. This is not a fault with the new pack; it is the instrument recalibrating its internal threshold map. Run two full charge and discharge cycles through normal use, then perform the instrument's calibration routine, and the percentage indicator will stabilise at accurate levels.