Pentax D-LI90 K-7 Compatible Battery 7.4V 1250mAh

Pentax K-7 / K-5 / 645D / K-3 — 7.4V Li-ion Replacement Battery (D-LI90)

This is a 7.4V, 1250mAh Li-ion replacement for the Pentax D-LI90 battery cell. It fits the K-7, K-5, 645D, and K-3 bodies, along with the wider D-LI90 compatible range. The cell matches the OEM voltage rail, connector pinout, and physical envelope exactly.

• K-series and 645D compatibility: These bodies share the D-LI90 form factor and the same three-pin communication interface. The BMS in each body reads cell voltage and temperature data over that interface — this cell transmits both correctly, so the battery indicator functions normally across the range.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a K-5 body. The BMS accepted the cell without error flags, full-charge cutoff triggered at 8.4V, and protection circuitry tripped correctly on simulated over-discharge at 5.8V.
• First-cycle initialisation on K-series bodies: K-series bodies map the battery-remaining percentage to a known discharge curve. On the first install, charge the cell fully inside the camera body using the OEM or compatible AC adapter — this lets the BMS calibrate its fuel gauge to the new cell's curve before you shoot.

Why the K-7 battery indicator locks at a fixed percentage after inserting a new cell

The K-7 stores a learned discharge curve from the previous cell. When a new cell goes in, the body compares real-time voltage readings against that stored profile — if they don't align, the indicator stalls or reads incorrectly. A full charge-and-discharge cycle from inside the camera body clears the old profile and maps a fresh curve. After one complete cycle, the percentage display tracks normally through the cell's actual charge state.

Battery percentage jumping erratically during a shoot on the K-5 or K-3

This happens when the body's voltage-threshold table doesn't match the new cell's discharge curve. The K-5 and K-3 read voltage at fixed intervals and translate that to a percentage using a pre-mapped table — a replacement cell with a slightly different mid-discharge plateau causes the reading to skip steps. The fix is the same calibration cycle: charge fully in-body to 8.4V, shoot until the low-battery warning triggers, then recharge fully. The body re-maps the table on that first full cycle and the display stabilises.