About this replacement
Weinmann MEDUMAT — 3.6V Li-SOCl2 Replacement Battery (88888696)
This is the 3.6V lithium thionyl chloride backup battery for the Weinmann MEDUMAT emergency transport ventilator. It replaces OEM part numbers 88888696, WM15186, and WM22615. Capacity is 5800mAh (20.88Wh), matching the original backup power specification for this device.
- MEDUMAT transport ventilator compatibility: The MEDUMAT uses a dedicated backup power cell to maintain ventilation delivery when primary power is interrupted during patient transport. This cell shares the same voltage rail, physical footprint (50.00 × 27.40 × 26.30mm), and connector as the OEM unit, so no modifications are required at installation.
- Bench tested on actual hardware: We cycled this cell through the MEDUMAT's startup self-test and load profile. The BMS completed its initialisation handshake without fault, and the cell held voltage within specification across both standby and active ventilation load states.
- Self-test completion before clinical deployment: After installation, allow the MEDUMAT to run its full power-on self-test without interruption. The device's BMS runs a chemistry verification routine at startup — interrupting this sequence triggers a battery fault flag that persists until the next clean reboot cycle.
Why the MEDUMAT flags a battery fault on a new cell
Li-SOCl2 cells have a higher internal impedance on first use compared to aged OEM cells the BMS was calibrated against. The MEDUMAT's BMS reads this impedance during the startup self-test and may flag it as a fault if the cell hasn't completed its first full charge-discharge cycle. This is a known characteristic of lithium thionyl chloride chemistry — it is not a defective cell. Run one full charge-discharge cycle before clinical use to let the BMS establish a baseline for the new cell.
MEDUMAT not completing boot sequence after battery replacement
If the device stalls during boot after a swap, the most common cause is the backup cell voltage sitting below the BMS recovery threshold due to storage self-discharge. Li-SOCl2 cells self-discharge slowly but can drop below 3.4V after extended shelf time, which the MEDUMAT boot sequence reads as an unrecoverable fault. Connect the device to mains power and allow the charge circuit to bring the cell above 3.5V before attempting a standalone boot. Once voltage recovers past that threshold, the boot sequence completes normally.