Panasonic EB-BSD75 Replacement Battery 3.7V 700mAh

Panasonic GD75 / GD76 — 3.7V Li-ion Replacement Battery (EB-BSD75)

This is a 3.7V, 700mAh Li-ion cell built to replace the original EB-BSD75 battery in the Panasonic GD75 and GD76 mobile phones. It fits the battery bay directly and connects to the same contacts the original cell used. Capacity is 700mAh (2.59Wh) — identical to the factory specification.

• GD75 and GD76 compatibility: Both handsets share the same battery bay dimensions, contact layout, and 3.7V supply rail. One cell covers both models — no adapter or modification needed.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on GD75 hardware. The BMS accepted the charge IC handshake cleanly and held voltage within spec across the full discharge curve.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter to the new cell's actual discharge curve before high-current charging is introduced into an uncalibrated state.

Why the GD75 reports wrong battery percentage after a cell swap

The GD75 uses a fuel gauge IC that builds its charge estimate from a stored discharge curve calibrated to the original cell. When a new cell goes in, that curve no longer matches the actual cell chemistry. The IC keeps reporting percentages based on old data until it re-learns. One complete discharge down to auto-shutoff, followed by a full uninterrupted charge to 4.2V, resets the calibration baseline. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC hasn't calibrated yet and the phone's reported percentage doesn't reflect actual cell voltage. Under modem or screen load, the cell voltage drops sharply at a point the IC doesn't expect — the protection circuit trips and the phone cuts off. It isn't a fault with the cell. Run one full calibration cycle first: discharge fully until the phone shuts itself down, then charge uninterrupted to 100%. The shutdowns stop once the IC has a real voltage curve to work from.