G-CARE SP-800 Compatible Battery 7.4V 3400mAh Li-ion

G-CARE SP-800 — 7.4V Li-ion Replacement Battery (BAK-18650C4*2)

This is a 7.4V, 3400mAh Li-ion battery pack for the G-CARE SP-800 portable medical device. It replaces the original BAK-18650C4*2 pack when capacity has faded or the original cell has failed. The SP-800 is clinical equipment — this replacement carries the same voltage and capacity spec the device expects.

• SP-800 platform fit: The SP-800 runs a 7.4V dual-cell Li-ion architecture. The BMS on this device handshakes with the pack at startup to confirm voltage range and cell chemistry. This replacement matches that voltage rail and cell configuration, so the device completes its power-on verification without throwing a battery fault.
• Bench tested on actual hardware: We cycled this pack through charge and discharge under load conditions consistent with portable medical device draw profiles. The BMS protection circuits responded correctly to charge cutoff at 8.4V and discharge cutoff at 6.0V. No thermal events, no false fault codes on the first three cycles.
• Post-installation self-test protocol: After fitting this battery, let the SP-800 complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power mid-sequence stores a false battery fault in firmware that persists until the next clean reboot from full charge.

Why the SP-800 reports a battery fault after a confirmed full charge

The SP-800's charge IC applies a conservative charge threshold on cells it hasn't profiled yet. A new pack often reaches 8.2–8.3V before the device registers it as "full," which sits below the OEM battery's learned 8.4V ceiling. The BMS compares the measured endpoint against a stored reference from the previous cell, and a mismatch triggers a fault flag. Run one complete charge-discharge cycle on the SP-800 before clinical use — after that cycle, the device recalibrates its threshold against the new cell's actual chemistry.

SP-800 not completing boot after battery sat in storage

Li-ion cells self-discharge during storage at roughly 2–3% per month. If this pack sat unused long enough, cell voltage may have dropped below the SP-800's BMS recovery threshold — typically around 6.0V for a 7.4V nominal pack. Below that point, the BMS locks out discharge to protect the cells, and the device won't power on even when connected to the charger. Place the battery on the charger for a full uninterrupted charge cycle first; if the charger's indicator light activates and progresses normally, the BMS has cleared the lockout and the pack is recovering to a usable voltage.