About this replacement
IMEX Free DOP Probe / DOP CT Series — 12V Ni-MH Replacement Battery (BT0024)
This is a 12V 230mAh Ni-MH replacement battery for the IMEX Free DOP Probe, DOP CT, CT Plus Doppler, and Free DOP family of handheld Doppler diagnostic probes. It replaces OEM part numbers BT0024, C631, AVT100100, and BT-U024. Voltage and connector match the original cell exactly.
- Free DOP and DOP CT platform fit: These models share the same 12V Ni-MH cell format, BMS handshake protocol, and physical footprint. A single replacement cell covers the full probe family without modification.
- Bench tested on actual hardware: We ran the cell through a full charge cycle and monitored BMS communication. The protection circuit accepted the new cell, completed charge termination correctly, and passed discharge verification without fault flags.
- Self-test cycle after installation: After fitting the new battery, allow the probe to complete its full power-on self-test without interruption. Medical device BMS firmware runs a verification sequence at startup — cutting power mid-sequence triggers a persistent battery fault that clears only on the next full, uninterrupted reboot.
Device not completing boot sequence on a new BT0024 cell
The Free DOP BMS checks cell voltage against a stored threshold during the power-on sequence. A new Ni-MH cell that has partially self-discharged in storage may read below that threshold even when it still holds usable charge. The BMS interprets this as an unsafe cell and halts the boot before the device reaches the main operating screen. Charge the replacement cell fully before first installation — the charge IC will bring it to 12V nominal, and the boot sequence will clear on the next power-on.
Low battery alarm triggered immediately after a confirmed full charge
This happens when the BMS compares the new cell's discharge curve against parameters learned from the previous aged cell. A fresh Ni-MH cell has a slightly different internal resistance profile, which the BMS reads as an early voltage sag under load — triggering a low battery flag even at near-full capacity. The alarm typically clears after one complete charge-discharge cycle, which allows the BMS to recalibrate its state-of-charge model to the new cell. Run one full cycle before using the probe in a clinical setting.