About this replacement
Reichert PT100 Tonometer — 3.7V Li-ion Replacement Battery (13851-873)
This 3.7V, 2600mAh Li-ion cell replaces OEM part 13851-873 in the Reichert PT100 Tonometer and EPG-1446. The PT100 is a portable ophthalmic device used in clinical settings to measure intraocular pressure. Voltage and capacity match the original spec exactly so the device BMS recognises the cell at startup.
- PT100 and EPG-1446 platform fit: Both devices share the same 3.7V power rail, connector pinout, and BMS handshake protocol, which is why a single cell covers both. No adapters or wiring changes needed.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the PT100 platform. The BMS completed its verification handshake without triggering a fault flag, and the charge IC accepted the cell without rejecting it as out-of-spec.
- First-use cycle on medical hardware: After installing this cell, allow the PT100 to complete its full power-on self-test without interrupting it. The device BMS runs a chemistry verification sequence at startup — cutting power mid-sequence locks in a false battery fault that persists until the next clean reboot.
PT100 self-test failure after battery swap
The PT100 runs a BMS learn cycle the first time a new cell is seated. If the device has not yet completed one full charge-discharge cycle on the new cell, the BMS may log a self-test fault and prevent clinical operation. This is not a defective cell — it is the device validating that the new battery meets its internal charge profile. Run one complete charge to full, then discharge through normal use, before relying on the device clinically. After that cycle, the BMS clears the flag and operates normally.
Low battery alarm triggering immediately after a confirmed full charge
This happens when the BMS compares the new cell's resting voltage against a threshold calibrated to the OEM cell's chemistry signature. A new Li-ion cell that has not yet been cycled can sit slightly below 4.15V at rest even after a full charge — enough to trip the alarm threshold on the first boot. The fix is one full charge-discharge cycle, which lets the cell reach its stable resting voltage and allows the BMS to recalibrate its low-battery trigger. After the first cycle, the alarm clears at a full charge reading of approximately 4.2V.