Inditherm Cosytherm Replacement Battery 26.4V 3700mAh Part 110751

Inditherm Cosytherm Mattress Heating System — 26.4V Ni-MH Replacement Battery (110751)

This is a 26.4V, 3700mAh Ni-MH replacement battery for the Inditherm Cosytherm mattress heating system. It matches OEM part number 110751 and fits the Cosytherm unit used in medical and clinical settings for patient temperature regulation. Capacity is 97.68Wh — identical to the original specification.

• Cosytherm platform fit: The Cosytherm controller draws from a single battery pack running a tightly regulated 26.4V rail. The BMS in these units validates cell chemistry at startup — Ni-MH cells must match voltage profile and internal resistance expectations or the controller flags a battery fault before the heating element activates.
• Bench tested on actual hardware: We cycled this pack through full charge-discharge runs and monitored BMS handshake behaviour. The protection circuit responded correctly to charge termination via delta-V detection, which is standard for Ni-MH at this voltage tier.
• First-cycle initialisation on the Cosytherm unit: After installing this battery, let the Cosytherm complete its full power-on self-test without interrupting the sequence. The BMS runs a verification pass at startup — cutting power during this window stores a false battery fault that persists until the unit is rebooted cleanly from a fully charged state.

Why the Cosytherm controller flags a fault on a new Ni-MH pack

The Cosytherm BMS checks internal resistance and open-circuit voltage at startup against stored OEM thresholds. A new Ni-MH cell that has been sitting in storage will have slightly elevated internal resistance and a resting voltage below the controller's pass threshold. This triggers a battery fault even though the pack is electrically sound. One full charge-discharge cycle normalises cell resistance and brings resting voltage in line — the fault clears after that cycle completes.

Charge indicator stalling below 100% on the first charge

Ni-MH chargers terminate charge via a negative delta-V signal — the slight voltage drop that occurs when the cell reaches capacity. On a new pack, cells are not yet matched in charge acceptance, so the delta-V signal arrives earlier than expected and the charge IC stops short of displaying 100%. This is not a fault — it is the charger responding correctly to cell behaviour on the first cycle. Run two to three full charge-discharge cycles and the charge indicator will reach 100% consistently as cells balance. Do not interrupt these early cycles.