About this replacement
Fukuda FX-7102 / FCP-7101 Series — 9.6V Ni-MH Replacement Battery (MB333BHR-4/3AU)
This is a 9.6V 4000mAh Ni-MH replacement battery for the Fukuda FX-7102, FCP-7101, FX-7000, and Cardimax FX-7102 electrocardiograph systems. It matches OEM part numbers MB333BHR-4/3AU and 8PH-4/3A 3700-H-J18. These are portable cardiac diagnostic devices used in clinical and ambulatory settings.
- FX-7102 and FCP-7101 platform compatibility: These models share the same 9.6V battery rail, physical connector, and BMS handshake protocol — one cell pack covers the full group. The BMS on each device reads cell voltage and temperature during the power-on sequence, so chemistry match matters.
- Bench tested on actual hardware: We cycled this cell through charge and full-load discharge on the FX-7102 platform. The BMS cleared voltage and temperature checks cleanly by the second full cycle. No false low-battery flags triggered after cycle two.
- Power-on self-test sequence: After installing this battery, let the device complete its full startup self-test without interruption. The ECG's BMS runs a verification sweep at boot. Cutting power during that sweep stores a fault flag that persists until the next clean reboot — a common cause of repeat low-battery warnings on a fully charged pack.
Low battery alarm on the FX-7102 immediately after a confirmed full charge
The FX-7102 BMS was calibrated against aged OEM cells with a compressed voltage curve. A new Ni-MH cell has a flatter, higher mid-charge voltage that the BMS can misread as "not fully charged" on the first one or two cycles. This triggers the low-battery alarm even when the pack is at full capacity. Run one complete charge-discharge-recharge cycle before clinical use. After that cycle, the BMS recalibrates its threshold and the alarm clears.
Device will not power on after the replacement battery sat 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 FX-7102's BMS recovery threshold — typically around 8.4V for a 9.6V Ni-MH pack — and the device simply will not boot. Connect the battery to the device charger and leave it for a full uninterrupted charge cycle before attempting power-on. If the charge indicator does not respond within 30 minutes, check charger output voltage at the connector — it should read between 10.5V and 12V DC.