About this replacement
Biohit Picus Series — 3.7V Li-Polymer Replacement Battery (SA 736000)
This 3.7V, 450mAh Li-Polymer battery replaces the OEM cell in the Biohit Picus, Picus NxT, Picus 2, and multichannel pipette models. It powers the motorized aspiration and dispensing mechanism in these electronic pipettes. Swap it when the original cell no longer holds charge or fails the device's internal battery check.
- Picus family compatibility: The Picus, Picus NxT, Picus 2, and multichannel variants share the SA 736000 battery format — same 3.7V rail, same physical envelope (38.80 × 20.80 × 6.90mm), and the same BMS handshake protocol. Swapping between these models does not require a different cell.
- Bench tested on actual hardware: We cycled this cell through the Picus power-on sequence and confirmed the BMS accepted the new cell without throwing a persistent fault. Charge acceptance and discharge curve matched OEM spec across the first three full cycles.
- Post-swap self-test protocol: After installing this battery, allow the Picus to complete its full power-on self-test without interruption. The device runs a BMS verification at startup — cutting power during this sequence causes a false battery fault flag that persists until the next clean reboot.
Why the Picus charge indicator stalls below 100% on a new cell
The Picus charge IC applies a conservative current limit when it first encounters a new Li-Polymer cell with an unfamiliar charge history. This causes the indicator to plateau at 80–95% and appear stuck. It is not a fault — the IC is running a cautious top-up phase. Complete a full charge cycle without removing the battery and the indicator will reach 100% on the second charge.
Picus shutting off mid-dispense in the first week after battery replacement
A new Li-Polymer cell has slightly higher internal resistance before the electrolyte fully conditions — typically across the first 8–10 cycles. During a rapid multi-dispense sequence, the momentary current draw causes a brief voltage sag that the BMS reads as an undervoltage event and trips the cutoff. This is not a defective cell. Run the pipette through 10 full charge-discharge cycles under normal lab workload and the sag will reduce as internal resistance drops. If shutdowns continue beyond cycle 10, check that the cell is seated flush and the connector contact is clean.