About this replacement
Sanyo SCP-5000 / SCP-5100 / SCP-5150 — 3.7V Li-ion 1500mAh Replacement Battery
This is a 3.7V Li-ion cell rated at 1500mAh (5.55Wh), made to fit the Sanyo SCP-5000, SCP-5100, and SCP-5150 flip phones. These mid-2000s devices use a slim single-cell pack with a three-contact connector tied to the onboard fuel gauge IC. Swap it in when the original cell no longer holds enough charge for daily calls and texts.
- SCP-5000 / 5100 / 5150 platform fit: All three models share the same battery bay geometry, connector pinout, and 3.7V nominal rail. The BMS on each handset reads cell voltage through the same contact arrangement, so one cell covers all three without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SCP platform and confirmed the BMS accepted the new cell without lockout. Voltage held steady through the mid-range discharge curve with no premature cutoff at the protection IC threshold.
- Fuel gauge recalibration on first cycle: After fitting the new cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before normal use. The SCP-series coulomb counter is calibrated against the old cell's curve — skipping this step causes the percentage display to read inaccurately from day one.
Why the SCP-5000 reports wrong battery percentage after a cell swap
The SCP-series fuel gauge IC tracks charge state using a coulomb counter that learned the discharge curve of the original cell over many cycles. A new cell has a slightly different internal resistance and voltage-versus-capacity profile. Until the IC re-maps that curve, the percentage display drifts — often reading 40% when the phone is close to shutdown. One full discharge-to-auto-off followed by a full uninterrupted charge resets the reference points the counter uses.
Sudden shutdown at 20–30% on the replacement cell
This happens when the modem fires during a call or the backlight surges and pulls more current than the cell can sustain at that state of charge. The cell voltage dips below the 3.0V protection cutoff under load even though the gauge shows charge remaining. The fuel gauge IC hasn't yet mapped the new cell's voltage cliff accurately, so it doesn't warn the OS in time. Run the full calibration cycle first — one complete discharge to shutdown, then a full charge to 4.2V — before judging the cell's actual capacity.