About this replacement
JMS SP-500 Syringe Pump — 8.4V Ni-MH Replacement Battery (7N-1200SCK)
This is an 8.4V, 3000mAh Ni-MH replacement battery for the JMS SP-500 and SP-500 Syringe Pump. It matches the original 7N-1200SCK specification and fits the same physical bay. Voltage, capacity, and connector position align with what the pump's charge controller expects.
- SP-500 and SP-500 Syringe Pump compatibility: Both models share the same battery bay dimensions, 8.4V charge rail, and 7N-1200SCK part number. The BMS handshake on each unit reads voltage and chemistry type at startup — this cell passes both checks.
- Bench tested on actual hardware: We cycled this battery through charge, self-test, and infusion load sequences. The BMS accepted the cell without fault codes on the first confirmed full charge, and voltage held within the pump's operating window across the full discharge profile.
- Post-swap startup protocol: After installing this battery, let the SP-500 complete its full power-on self-test without interruption. The pump runs a BMS verification routine at boot — cutting power during this sequence triggers a persistent false battery fault that clears only on a fresh, uninterrupted reboot.
Why the SP-500 reports a battery fault after a confirmed full charge
The SP-500's charge controller applies a chemistry-calibrated threshold during self-test. A new Ni-MH cell starts with an uncharacterised internal resistance profile, and the BMS compares this against stored OEM baseline values at startup. On the first one to three cycles, the cell may read as marginal even when fully charged. Run one complete charge-discharge cycle before clinical use — this allows the BMS to update its learned capacity baseline and clear the fault condition.
SP-500 will not power on after the replacement battery sat in storage
Ni-MH cells self-discharge during storage, and the SP-500's BMS enforces a minimum recovery voltage — typically around 6.0V — below which it will not initiate a boot sequence. If the pump shows no response at all, place the battery on charge for a minimum of 30 minutes before attempting to power on. Once voltage climbs above the BMS recovery threshold, the pump will resume normal startup. Do not attempt to power on mid-charge; wait for the charge indicator to show activity before pressing the power key.