CHC X91 Survey Receiver Replacement Battery 7.4V 2600mAh

CHC X91 / X93 / X900 GNSS Receiver — 7.4V Li-ion Replacement Battery (1906110059)

This 7.4V, 2600mAh Li-ion pack replaces OEM part 1906110059 in CHC X91, X93, and X900 GNSS receivers. These are field-deployed geodetic and construction survey instruments that run continuous satellite positioning sessions. Voltage and capacity match factory spec exactly — no modification required.

• X91, X93, and X900 compatibility: All three receivers share the same battery bay geometry, connector pinout, and BMS handshake protocol. The pack communicates state-of-charge data over the bus — the receiver reads remaining capacity and displays it on the status screen without any adapter or reprogram.
• Bench tested on actual hardware: We cycled this pack through the X91's full satellite acquisition sequence and logged the discharge curve under sustained GNSS tracking load. The BMS held the protection threshold and did not trip during the high-draw initialisation phase when the RF board and antenna bias current peak simultaneously.
• Post-install calibration cycle: After fitting a new pack, run one complete calibration cycle through the instrument's system menu before field deployment. The X91 maps battery state during that cycle — skip it and the receiver's low-battery threshold reads against stale reference data, triggering early warnings on the first survey session.

BMS lockout on the X91 after the pack sat unused in a carry case for months

Li-ion cells self-discharge slowly during storage. If the pack drops below approximately 2.5V per cell, the BMS trips an over-discharge lockout and the receiver will not power on — even connected to a charger. The charger sees the protection circuit blocking current and reports no charge accepted. To recover, apply a compatible Li-ion charger directly to the pack terminals at a low pre-charge current (under 100mA) until cell voltage climbs above 3.0V per cell. Once above that threshold, the BMS releases and normal charging resumes.

X91 shuts down mid-session while the status screen still shows charge remaining

This happens when cell internal resistance has risen enough that voltage sags sharply under the combined load of the RF tracking board, antenna bias, and data logging. The displayed percentage is calculated at rest voltage — it does not account for the sag under live load. When the voltage dips below the BMS cutoff threshold during a sustained draw spike, the receiver shuts off even though the resting indicator looked healthy. Fitting a new pack with low internal resistance eliminates the sag — confirm the pack recovers to above 7.2V within 30 seconds of disconnecting the receiver after a shutdown event.