ShinewayTech S20A 9.6V Replacement Battery AC-BAT-30

ShinewayTech S20A / S20B / S20C / S20N — 9.6V Ni-MH Replacement Battery (AC-BAT-30)

This is a 9.6V, 2000mAh Ni-MH replacement for the ShinewayTech AC-BAT-30 battery pack. It fits the S20A, S20B, S20C, and S20N portable survey and test instruments. The pack slots into the same bay as the original and connects through the same three-contact interface.

• S20 series shared platform: The S20A, S20B, S20C, and S20N all draw from the same 9.6V rail and use the same physical bay and BMS handshake protocol. One pack fits the full line because ShinewayTech standardised the power system across these variants — connector pinout, thermal cutoff thresholds, and charge termination logic are identical.
• Bench tested on actual hardware: We cycled this pack through charge and sustained sensor-load discharge on S20-class test gear. The BMS handled probe initialisation current spikes without tripping into lockout, and charge termination fired cleanly at the delta-V peak — no overcharge detected across three consecutive cycles.
• Post-install calibration requirement: After fitting this pack, run a full calibration cycle through the instrument menu before taking it to the field. The S20 maps battery state during calibration — skip this step and the instrument will flag premature low-battery warnings on your first measurement session even with a full charge.

BMS lockout after the S20 pack sat unused in a carry case for months

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. Left in a case for several months, the pack can drop below 0.9V per cell — the threshold where the S20's BMS enters a protective sleep state and refuses to accept a standard charge cycle. The instrument powers on briefly then cuts off, or the charger shows no response at all. To recover, apply a low-current trickle charge (below 0.1C) directly to the pack terminals until the cell stack climbs above 8.5V, then transfer to the standard charger to complete the cycle.

Readings resetting or dropping out mid-logging session

This is not a software glitch — it is a voltage dropout event. Under sustained sensor load during a logging session, an aged or partially discharged pack can sag below the S20's minimum operating voltage for long enough to trigger a processor reset. The instrument restarts, and any buffered data in that session is lost. The fix is to ensure the pack is charged to at least 9.2V before starting a long logging run — check the voltage indicator in the instrument's system menu, not just the bar icon on the status screen.