About this replacement
Rigel Uni-Sim Vital Signs Simulator — 7.2V Ni-MH Replacement Battery (110847)
This is a 7.2V 2500mAh Ni-MH replacement battery for the Rigel Uni-Sim Vital Signs Simulator, OEM part number 110847. It fits the Uni-Sim directly and restores power to the simulator during clinical education sessions. Capacity is rated at 2500mAh (18Wh), matching the original specification.
- Uni-Sim platform fit: The Uni-Sim draws a stable low-current load across its display and sensor simulation circuits. This replacement uses the same 7.2V Ni-MH cell configuration and connector pinout as the OEM pack, so the device BMS recognises it without manual pairing or software intervention.
- Bench tested on actual hardware: We cycled this battery through charge and load on the Uni-Sim platform. The BMS completed its self-test sequence without fault flags, and cell voltage held above the low-battery cutoff threshold throughout the discharge curve at normal simulator load.
- Post-swap self-test protocol: After fitting this battery, let the Uni-Sim complete its full power-on self-test without interrupting or cycling power. The device runs a BMS verification routine at startup — cutting power mid-sequence can register a false battery fault that persists until the next clean reboot.
Why the Uni-Sim triggers a low-battery alarm with a freshly charged replacement
The Uni-Sim BMS is calibrated to the charge profile of a conditioned OEM cell. A new Ni-MH cell has not yet established full capacity and its internal resistance reads higher than a broken-in pack. The BMS interprets this elevated resistance as a partially discharged cell and raises the alarm even when the pack is at full charge. Running one complete charge-discharge-recharge cycle on the Uni-Sim normalises the cell parameters the BMS reads against. After that cycle, the alarm clears under normal operating conditions.
Uni-Sim won't power on after the battery sat unused in storage
Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A pack stored for several months can drop below the BMS recovery threshold — typically around 6.0V for a 7.2V six-cell pack — at which point the device refuses to boot rather than risk running on an unstable supply. Place the battery on charge for a full uninterrupted cycle before reinstalling it. If the charger does not recognise the deeply discharged pack, most Ni-MH chargers have a recovery or force-start mode that applies a trickle charge at around 0.1C to bring the cell voltage back above the detection floor before switching to normal charge rate.