Leica BP-DC12 Replacement Battery 7.4V 800mAh Li-ion

Leica V-Lux 4 / Leica Q — 7.4V Li-ion Replacement Battery (BP-DC12)

This is a 7.4V, 800mAh Li-ion replacement for the BP-DC12 battery. It fits the Leica V-Lux 4 and Leica Q cameras. Dimensions are 48.00 × 36.00 × 17.10mm — same physical footprint as the OEM cell.

• V-Lux 4 and Leica Q compatibility: Both cameras run the same 7.4V nominal rail and use the same BP-DC12 form factor with identical connector pinout and BMS handshake protocol — one cell covers both bodies without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the V-Lux 4 body. The BMS accepted the cell on first insertion, reported battery status correctly, and protection circuitry tripped at appropriate low-voltage thresholds without false cutoffs during write-heavy burst sequences.
• First-install charge cycle on the V-Lux 4: Insert the new cell and run a full charge cycle through the camera body or OEM charger before your first shoot. The V-Lux 4 BMS maps its battery-remaining display to the discharge curve — skipping this step can cause the indicator to read inaccurately from the first frame.

Why the Leica Q flags a new BP-DC12 as unrecognised on first insert

The Leica Q runs a BMS authentication check on every new cell it sees. A replacement cell that hasn't completed a charge handshake with the camera can trigger an incompatible or no-battery warning even when the cell is fully charged. This isn't a fault with the cell — it's the camera waiting for a charge cycle to register the new battery's profile. Insert the cell, connect the camera to the OEM charger, and let it complete one full charge from within the body. After that cycle, the warning clears and the indicator reads correctly.

Battery percentage jumping erratically on the V-Lux 4 display

The V-Lux 4 maps its percentage indicator to voltage thresholds calibrated for the original cell's discharge curve. A new replacement cell discharges along a slightly different curve until the BMS learns it — this causes the display to jump non-linearly, skipping from 80% to 40% or similar gaps. The fix is two to three full charge-discharge cycles through the camera body, which lets the BMS recalibrate its threshold mapping to the new cell. After conditioning, the display stabilises and tracks accurately down to the 3.0V per-cell cutoff.