About this replacement
Siemens SL65 / SL75 — 3.7V Li-ion Replacement Battery (EBA-650)
This is a 3.7V, 750mAh Li-ion battery replacing the original EBA-650 cell in the Siemens SL65, SL65 ESCDMA, and SL75 mobile phones. It matches the original 45 × 36 × 6mm footprint and the three-contact connector on the battery bay. Capacity is 750mAh — same as the factory spec.
- SL65 and SL75 platform fit: The SL65, SL65 ESCDMA, and SL75 all share the same battery bay dimensions, connector pinout, and charge IC handshake. One cell covers all three variants without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SL65 platform. The BMS accepted the charge IC handshake on the first cycle, and protection circuitry tripped correctly at the low-voltage cutoff threshold.
- Fuel gauge recalibration on first use: On first use after installation, run one full discharge down to automatic shutoff, then charge uninterrupted to 100% before normal use. The SL65 fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve during this cycle — skipping it causes the percentage readout to drift or jump in the first week of use.
Sudden shutdown at 20–30% on the SL65 after a cell swap
The SL65 shuts down mid-use despite the display showing charge remaining because the fuel gauge IC is still mapped to the old cell's voltage-capacity curve. A fresh Li-ion cell has a steeper voltage cliff under GSM transmit load — the phone's modem draws a burst current spike, voltage drops below the protection threshold, and the BMS cuts power before the display catches up. This is not a fault in the replacement cell. One full discharge-charge cycle lets the coulomb counter remap to the new cell's actual curve, and the early shutdowns stop.
Phone feels warm near the battery during the first few charges
A new high-impedance cell generates more heat during the initial charge cycles than a broken-in cell does. The SL65 charge IC pushes a constant current into higher internal resistance, and that converts to heat until the cell's impedance drops after a few cycles. This is normal and temporary. If the phone stays warm past the third full charge cycle, check that the battery contacts are clean and making full contact — partial contact increases resistance further and sustains the heat.