Mediana YM1000 Replacement Battery 8.4V 7600mAh

Mediana YM1000 / YM5500 — 8.4V Ni-MH Replacement Battery (M6021-0)

This is an 8.4V, 7600mAh Ni-MH replacement battery for the Mediana YM1000 and YM5500 portable TENS units, and the Moteur Vital Signs monitor. It replaces OEM part number M6021-0. Capacity matches the original cell pack — no modification required at the battery bay.

• YM1000, YM5500, and Moteur Vital Signs compatibility: All three platforms share the M6021-0 form factor, the same 8.4V nominal rail, and the same physical connector. The BMS in each device reads the same charge termination signal, so no firmware unlock or adapter is needed.
• Bench tested on actual hardware: We cycled this cell pack through charge, load, and termination on a YM1000 unit. The BMS accepted charge without triggering a false fault, and the load profile across stimulation output remained consistent through ten full cycles.
• Post-swap startup protocol: After installing this battery, allow the YM1000 or YM5500 to complete its full power-on self-test without interrupting it. Medical device BMS verification runs at startup — cutting power mid-sequence locks in a false battery fault that persists until the next clean reboot.

Why the YM1000 alarms low battery immediately after a confirmed full charge

The YM1000 BMS uses a stored capacity baseline from the previous cell to evaluate charge state at startup. A new cell has no history in that register, so the device reads the voltage curve as below threshold and triggers the alarm. This is not a faulty battery — it is a learn-cycle gap. Run one complete charge-to-discharge cycle and the BMS resets its baseline to the new cell's actual capacity curve. The alarm clears after that first full cycle.

YM1000 will not power on after the replacement battery sat in the box for several months

Ni-MH cells self-discharge during storage — typically dropping to around 1.0V per cell or below over several months. At that level, the BMS recovery threshold is not met and the device refuses to boot. Place the battery on charge immediately and leave it connected for a full charge cycle before attempting to power on the unit. Once the pack reaches approximately 8.4V, the BMS re-initialises and the device will boot normally.