Profoto A1 Replacement Battery 7.4V 2500mAh Li-ion

Profoto A1 / A1x / A10 / A2 — 7.4V Li-ion Replacement Battery (29597)

This 7.4V 2500mAh (18.5Wh) Li-ion cell replaces the OEM battery in the Profoto A1, A1x, A10, and A2 on-camera strobe lights. All four models share the same battery bay geometry, connector pinout, and BMS communication protocol, so one cell covers the full lineup. Capacity figure is from product data — 2500mAh.

• A1, A1x, A10, and A2 compatibility: Profoto standardised the battery format across this generation of shoe-mount strobes. Voltage rail, physical housing, and BMS handshake are identical — the flash head reads cell state of charge through the same three-pin protocol on all four models.
• Bench tested on actual hardware: We cycled this cell through repeated full-power capacitor recharge sequences. The BMS held stable under the high-current draw each recharge cycle demands, and cell temperature stayed within normal range across a sustained high-power run.
• First-fit initialisation on the A1 series: After seating a new cell, power the flash fully off and back on from cold before firing the first shot. The BMS handshake that syncs cell state-of-charge to the flash's display completes only on a cold boot — inserting a cell into a flash that was already powered skips that handshake and can cause inaccurate battery indicators.

Flash output stepping down after 10–15 full-power shots

At full power, the A1 series recharges its capacitor bank with a high current draw that spikes cell voltage sag. A cell with elevated internal resistance — either aged or not yet conditioned — cannot sustain the voltage the BMS expects during that spike. The flash firmware interprets the sag as low charge and throttles output to protect the cell. Five full charge-discharge conditioning cycles reduce internal resistance and restore consistent full-power delivery.

Recycle time between shots slower than the previous cell

New Li-ion cells ship with higher internal resistance than a broken-in cell at the same chemistry. That resistance limits how fast charge can flow into the capacitor, stretching recycle time. This is not a defect — it normalises after five conditioning cycles of full discharge followed by a full charge. After conditioning, recycle time on the A1 at mid-power settings should return to the interval the previous cell delivered.