Pentax D-LI7 Optio 450 Replacement Battery 3.7V 1800mAh

Pentax Optio 450 / 550 / 750 Series — 3.7V Li-ion Replacement Battery (D-LI7)

This is a 3.7V, 1800mAh Li-ion cell built to the D-LI7 specification. It fits the Pentax Optio 450, 550, 555, and 750 series compact digital cameras. Voltage and connector dimensions match OEM spec exactly, so the battery seats and contacts without modification.

• Optio 450 / 550 / 555 / 750 platform fit: These models share the same battery bay dimensions, 3.7V power rail, and D-LI7 contact layout. One cell covers all four bodies without adapter plates or rewiring.
• Bench tested on actual hardware: We cycled this cell through the Optio 450 body and confirmed the BMS accepted the cell at first charge, held the voltage curve through mid-discharge, and tripped the low-battery warning at the correct threshold before cutoff.
• First charge via camera body: Some Optio bodies need one full charge cycle completed inside the camera — not just through a standalone charger — before the battery-remaining indicator reads accurately. Run the first charge in-body if the display shows erratic percentages.

Flash recycling slowing down before the battery indicator drops

The Optio's flash capacitor pulls a sharp current spike during recharge between shots. As a Li-ion cell approaches the lower end of its discharge curve — roughly 3.5V — internal resistance rises enough to slow that capacitor recharge, even though the battery indicator still shows partial charge. You'll notice longer gaps between ready flashes before the camera ever shows a low-battery warning. Swapping to a fresh cell, or topping up to above 3.7V open-circuit, restores normal recycle speed.

Battery percentage jumping erratically on the Optio display

The Optio body maps its battery indicator against a fixed voltage-to-percentage table calibrated for the original D-LI7 discharge curve. A new replacement cell can have a slightly different discharge curve slope, causing the indicator to jump — say, from 80% to 45% mid-shoot without warning. This is a calibration mismatch, not a faulty cell. Run two or three full charge-and-discharge cycles through the camera body and the indicator mapping will stabilise against the new cell's actual curve.