About this replacement
OleumTech WT-XXXX-HL1 / HL2 & C1D1 Transmitters — 3.6V Li-SOCl2 Replacement Battery (SX1000-BP3)
This is a 3.6V lithium thionyl chloride (Li-SOCl2) replacement battery rated at 28000mAh (100.8Wh), carrying OEM part number SX1000-BP3. It fits OleumTech WT-XXXX-HL1, WT-XXXX-HL2, and C1D1 OleumTech Transmitters used in remote monitoring, field data collection, and hazardous-location sensing applications. The Li-SOCl2 chemistry holds a flat discharge curve across wide temperature swings — a requirement for instruments left unattended in outdoor enclosures.
- WT-XXXX-HL1, HL2 and C1D1 platform fit: These three variants share the same battery bay dimensions and the same 3.6V voltage rail. The transmitter's internal power management circuit expects a Li-SOCl2 cell — substituting a different chemistry changes the discharge profile and causes false low-battery flags at the controller.
- Bench tested on actual hardware: We ran this cell under a simulated wireless transmission cycle — periodic sensor polling plus radio burst events. The cell held stable output through successive load pulses without tripping the protection circuit, and recovered cleanly between bursts.
- Post-installation calibration on WT-XXXX instruments: After fitting a new cell, run a full calibration cycle through the instrument menu before field deployment. The WT-XXXX maps battery state during that sequence — skipping it causes premature low-battery warnings to appear on the first active measurement session even when the cell is fully charged.
BMS lockout after a C1D1 transmitter sat unused for months
Li-SOCl2 cells in standby applications self-discharge slowly, but if a transmitter is stored with the battery installed for an extended period, the cell voltage can drop below the BMS recovery threshold. At that point the protection circuit latches off and the instrument appears completely dead. This is not a failed cell — it is a sleep-state the BMS enters to prevent over-discharge damage. Connecting the transmitter to its supply bus or a known-good load path for 30–60 seconds can re-initialise the BMS; target a recovery voltage above 3.2V before powering the instrument fully.
Readings drifting or resetting mid-session during sustained sensor logging
During a long logging session with multiple active sensors, the combined draw on the 3.6V rail can cause brief voltage sag at the moment each sensor polls. If the sag dips below the instrument's brown-out threshold, the microcontroller resets and the session log shows a gap or a jump in values. This is distinct from a flat battery — the cell has capacity remaining, but instantaneous current demand exceeds what a partially passivated cell can deliver cleanly. Warming the transmitter enclosure above 10°C before a session reduces passivation layer resistance and lowers the voltage sag under load spikes.