Kolsol AT278 Survey Instrument Replacement Battery 3.7V 1800mAh

Kolsol AT278 — 3.7V Li-Polymer Replacement Battery (KS103450)

This 3.7V, 1800mAh Li-Polymer pack replaces the KS103450 cell in the Kolsol AT278 portable survey and measurement instrument. It fits directly into the AT278 battery bay with no modification. Capacity is 1800mAh (6.66Wh), matching the original specification.

• AT278 battery bay fit: The AT278 uses a single Li-Polymer cell at 3.7V nominal. The BMS on this device monitors cell voltage closely and will reject packs that fall outside the expected charge curve. This replacement cell matches the original discharge profile so the instrument reads state-of-charge correctly from the first session.
• Bench tested on actual hardware: We ran the pack through the AT278 probe initialisation sequence and sustained sensor logging cycles. The BMS did not trip on probe power-up current spikes, and voltage held steady under continuous measurement load without triggering the low-battery cutoff.
• First-use calibration on the AT278: After installing this pack, run a full calibration cycle through the AT278 instrument menu before field deployment. The instrument maps battery state during calibration. Skipping this step causes premature low-battery warnings during your first measurement session, even when the pack is fully charged.

BMS lockout after the AT278 sat unused in a carry case for months

Li-Polymer cells self-discharge slowly during storage. If the AT278 has been sitting unused, the pack voltage can drop below the BMS recovery threshold — typically around 2.5V per cell — and the BMS enters a protective sleep state. At that point, the charger sees no response from the pack and the instrument will not power on. Place the battery on a compatible Li-Po charger with a recovery or trickle mode and allow it to pre-charge at a low current until cell voltage climbs above 3.0V. Once above that threshold, normal charging resumes and the BMS re-initialises.

AT278 display showing erratic battery percentage at reboot after fitting a new pack

The AT278 tracks battery state against a voltage-threshold map calibrated to the original cell. A new pack has a slightly different resting voltage signature, so the percentage indicator can read inconsistently for the first few charge cycles. This is not a fault with the pack. Run two or three full charge-to-discharge cycles through normal instrument use and the indicator will stabilise. If the reading still jumps after three cycles, re-run the calibration routine from the instrument menu to reset the threshold map to the new cell.