About this replacement
Profoto B10 / B10X Series — 14.4V Li-ion Replacement Battery (100440)
This is a 14.4V, 3400mAh (48.96Wh) lithium-ion battery for the Profoto B10, B10 Plus, B10X, and B10X Plus monolight flash units. It replaces OEM part number 100440 and slots into the same battery bay without modification. Voltage and connector match the original cell exactly.
- B10 and B10X family fit: The B10, B10 Plus, B10X, and B10X Plus all share the same 14.4V battery platform and bay geometry. The BMS handshake protocol and connector pinout are identical across the series, so one battery works across all four heads.
- Bench tested on actual hardware: We ran this cell through full-power flash cycles on the B10 platform and monitored the BMS communication with the dock. The protection circuit handled capacitor recharge current without tripping, and the dock moved cleanly from charge to ready state.
- First-fit power cycle — B10 and B10X: After fitting this cell, power the flash head fully off before firing the first shot. The BMS handshake initialises correctly only from a cold start. Swapping the battery mid-session without a full power cycle can prevent the head from reading the cell state accurately.
Flash output stepping down after 10–15 full-power shots
At full power, the B10's capacitor recharge draws high current from the battery in a short window. If the cell's internal resistance is elevated — either from age or from a new cell that hasn't been conditioned — voltage sags under that load. The B10 interprets this sag as low battery and steps down output to protect the capacitor charge circuit. Run five full charge-discharge cycles on the new cell and internal resistance drops, which tightens voltage delivery under recharge current and keeps output stable through longer burst sequences.
Dock cycling between charge and ready LED after a battery swap
This happens when the BMS handshake between the new cell and the dock hasn't completed cleanly. The dock reads an ambiguous state — not fully charged, not faulted — and oscillates between the two LEDs. Remove the battery from the head, seat it directly in the dock with the head disconnected, and let it complete a full charge cycle from cold. Once the dock holds a solid ready LED, the BMS state is confirmed and the battery will behave correctly in normal use. If the cycling persists past a full charge, check that the battery contacts are clean and fully seated — any resistance on the pins interrupts the handshake signal.