AeroTrak 700028 11.1V Survey Battery 7800mAh Li-ion

AeroTrak 700028 — 11.1V Li-ion Replacement Battery (LI202SX-7800)

This 11.1V, 7800mAh lithium-ion pack replaces the original AeroTrak battery used in portable survey and test instruments. OEM part numbers 700028, LI202SX, LI202SX-66C, LI202SX-78C, LI202SX-6600, LI202SX-7200, and LI202SX-7800 all cross to this unit. Capacity is 86.58Wh as rated from product specification.

• LI202SX variant coverage: The LI202SX family spans multiple suffix codes — 66C, 78C, 6600, 7200, 7800 — because AeroTrak sourced cells at different capacity points across production runs. The connector pinout and BMS handshake protocol stayed constant across all variants, so this 7800mAh pack slots into the same housing and communicates with the instrument firmware without modification.
• Bench tested on actual hardware: We cycled the pack under sustained sensor load to confirm BMS behaviour at the current thresholds these instruments apply during probe initialisation. The protection circuit held stable through repeated power-up events and did not trip on the inrush spike that a probe module draws at first contact.
• First-use calibration on survey instruments: After installing this pack, run a full calibration cycle through the instrument menu before field deployment. The instrument maps battery state during calibration. Skip this step and the low-battery warning triggers early on the first measurement session, cutting the session short even when the pack is at significant charge.

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

Li-ion cells self-discharge during storage. If the pack drops below approximately 2.5V per cell — roughly 7.5V total for a 3S pack — most BMS circuits enter a hard protection state and stop responding to the charger. The instrument will show no charge activity and may not power on at all. Place the pack on a charger that supports a low-voltage recovery or trickle mode; this applies a current small enough to bring cell voltage back above the BMS recovery threshold of around 8.4V without tripping overcurrent protection. Once the BMS exits lockout, normal charging resumes automatically.

Readings drift or reset mid-session during a continuous logging run

This is a voltage dropout issue, not a sensor fault. Under sustained sensor load, a degraded or partially charged cell can sag below the instrument's minimum operating voltage for a fraction of a second — long enough for the firmware to register a power interruption and reset the active measurement buffer. The instrument reboots or clears the log without any visible warning beforehand. Charge the pack fully before a logging session and confirm open-circuit voltage reads at least 12.4V before connecting to the instrument; anything below that indicates the pack has not completed its charge cycle.