GoPro Hero 8 Black Replacement Battery SPJB1B 3.85V 1220mAh

GoPro Hero 8 Black / Hero 7 Black / Hero 5 Black — 3.85V Li-ion Replacement Battery (SPJB1B)

This 3.85V, 1220mAh (4.7Wh) Li-ion cell replaces the GoPro SPJB1B battery across the Hero 5, 6, 7, and 8 Black action camera lineup. It fits the same physical bay and uses the same three-contact interface as the OEM cell. Swap it in when your original cell no longer holds a charge through a full shooting session.

• Hero 5–8 Black shared battery platform: GoPro standardised the SPJB1B footprint across four Hero Black generations — same 35.74 × 31.33 × 11.00mm dimensions, same contact layout, same BMS communication protocol. One cell fits all four bodies without modification.
• Bench tested on actual hardware: We ran this cell in a Hero 8 Black body and confirmed the BMS handshake completed on first insertion, the battery-remaining indicator populated correctly, and the protection circuit tripped cleanly at the low-voltage cutoff threshold during a full drain cycle.
• First-use charge cycle on Hero 8 Black: Charge this cell once through the camera body or OEM charger before heavy shooting. The Hero 8 Black's BMS maps percentage readout against the cell's discharge curve during that first charge — skipping it can cause the indicator to read erratically in early cycles.

Battery percentage jumping erratically on the Hero 8 Black display

The Hero 8 Black uses voltage-threshold mapping to estimate remaining charge. A new cell has a slightly different discharge curve than a worn OEM cell, so the camera's fuel gauge can misread it for the first few cycles. The indicator may jump from 80% to 50% without warning, then stabilise. Run two or three full charge-and-drain cycles and the readout settles — the BMS recalibrates its thresholds against the actual curve of the new cell.

Hero 8 Black showing dead-battery icon on a replacement cell that still has charge

This happens when the camera body cuts power at a voltage it reads as depleted, but the replacement cell's resting voltage sits slightly above the OEM cutoff point. The BMS is not rejecting the cell — it is misreading the state-of-charge on first use. Place the battery in the OEM charger or a compatible external charger and bring it to a full 4.2V before inserting it into the camera. That single full-charge pass clears the false-dead reading in most cases.