AdirPro 77GEB242 Survey Instrument Compatible Battery 14.8V 5800mAh

AdirPro 77GEB242 — 14.8V Li-ion Replacement Battery

This 14.8V 5800mAh Li-ion pack replaces the OEM 77GEB242 battery used in AdirPro surveying and measurement instruments. It fits the original battery slot and connector. Capacity is 5800mAh (85.84Wh), matched to the original specification.

• 14.8V four-cell Li-ion platform: AdirPro field instruments in this line run a 14.8V nominal rail — four cells in series. The BMS on this pack uses the same voltage thresholds and termination logic the instrument expects, so the pack communicates correctly through the battery contacts without triggering a voltage-mismatch fault.
• Bench tested on actual hardware: We ran this pack through instrument power-up, sensor initialisation, and sustained logging load. The BMS held steady through the probe power-up current spike and did not trip on the inrush. Cell voltage spread stayed within 30mV across a full discharge cycle.
• First-use calibration cycle: After installing this pack, run a full calibration cycle through the instrument menu before field deployment. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings during the first measurement session, even when the pack is fully charged.

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

Li-ion cells self-discharge slowly in storage. If an AdirPro instrument sits unused long enough, the pack voltage drops below the BMS recovery threshold — typically around 10V on a 14.8V four-cell pack. At that point the BMS enters a protective sleep state and the instrument will not power on at all, even when connected to a charger. The fix is to apply a low-current pre-charge using a compatible charger that supports recovery mode, which nudges cell voltage back above the reactivation threshold. Once the BMS wakes, normal charging resumes. If the pack does not respond after 30 minutes of pre-charge, the cells have likely dropped too far for recovery.

Readings drifting or logging session resetting mid-capture

This is a voltage dropout issue, not a firmware fault. During sustained sensor load — especially when multiple probes or communication modules are active simultaneously — cell voltage sags under the combined draw. If the sag crosses the instrument's low-voltage cutoff threshold, the device resets the active session to protect the measurement processor. The behaviour is more common with aged cells that can no longer hold voltage under load, but it can also appear with a new pack that was not calibrated after installation. Run the instrument's calibration routine first. If dropouts continue, check that the charger fully terminated the last charge — the pack should measure 16.6–16.8V at the terminals when fully charged.