TSI LI202SX-6600 Air Quality Monitor Compatible Battery 14.4V

TSI 8533EP / 8530EP Series — 14.4V Li-ion Replacement Battery (LI202SX-6600)

This is a 14.4V 5200mAh Li-ion replacement for the original LI202SX-6600 pack. It fits the TSI 8533EP, 8533, 8534, and 8530EP portable air quality monitors. Voltage and cell count match the original so the instrument's power rail and BMS handshake behave as expected.

• 8530EP and 8533EP platform fit: The 8530EP and 8533EP share the same 14.4V battery bay, connector pinout, and BMS communication protocol. The 8533 and 8534 use the same housing, so one SKU covers the full generation of this monitor line without any modification.
• Bench tested on actual hardware: We cycled this pack through instrument power-up, particle sensor initialisation, and sustained logging mode. The BMS held stable across the sensor's current spike at startup and did not trip under the combined draw of the pump motor and display backlight.
• Post-install calibration cycle: After fitting this pack, run a full calibration sequence through the instrument menu before field deployment. The 8533EP maps battery state during calibration, and skipping this step causes premature low-battery warnings during the first measurement session — even with a fully charged pack.

BMS lockout after the 8533EP sat unused in a carry case for months

When the 8533EP is stored without a charge top-up, the pack can discharge below the BMS recovery threshold — typically around 10–11V for a 14.4V Li-ion pack. At that voltage, the protection circuit locks out and the instrument shows no sign of life even when connected to the charger. The fix is to apply a slow pre-charge using a compatible Li-ion charger that supports recovery mode, bringing cell voltage up to at least 12V before the BMS re-enables normal charge current. Once the pack accepts a full charge cycle, the instrument powers on and operates normally.

Readings resetting or dropping out mid-session during continuous logging

This happens when cell voltage sags under the sustained combined load of the pump, sensors, and data logging — the instrument interprets the dip as a low-battery condition and resets the measurement loop to protect the log file. An aged original pack with reduced capacity reaches that sag point faster, but a worn pack at nominal voltage can still trigger it. With this replacement pack at full charge, the voltage floor under load stays above the instrument's cutoff threshold. If dropouts continue after fitting a new pack, check that the instrument firmware is current — some early 8533EP firmware versions had an aggressive low-voltage trip point that was revised in a later update.