Siemens C55 EBA-510 Replacement Battery 3.7V 750mAh

Siemens C55 / C56 / C61 / C70 Series — 3.7V Li-ion Replacement Battery (EBA-510)

This is a 3.7V, 750mAh Li-ion replacement battery for the Siemens C55, C56, C61, C70, and compatible models. It replaces the original EBA-510 cell when the existing battery no longer holds a usable charge. Dimensions are 50.20 × 37.50 × 7.65mm — confirm your existing battery matches before ordering.

• C55 / C56 / C61 / C70 compatibility: These models share the same battery bay dimensions, connector pinout, and 3.7V single-cell architecture. One EBA-510 replacement covers the full group without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the C55 platform. The BMS held charge termination correctly and showed no unexpected cutoff during mid-session load spikes from the display and GSM radio.
• Fuel gauge recalibration on first use: Disable any fast-charge accessory for the first complete discharge-to-charge cycle after installation. This lets the phone's fuel gauge IC map the new cell's discharge curve accurately before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the EBA-510 replacement cell

The C55 fuel gauge IC was calibrated against the original cell's discharge curve at the factory. A new cell with a slightly different internal resistance profile causes the IC to misread remaining capacity. Under GSM transmission load, the phone draws a sharp current spike — if the gauge underestimates state-of-charge, it triggers a protective shutdown before the cell is actually depleted. One full uninterrupted discharge cycle from 100% to automatic power-off, followed by a full recharge, resets the coulomb counter and corrects this behaviour.

Phone shows incorrect battery percentage after cell swap

The fuel gauge IC on the C55 stores a learned discharge curve from the previous cell. After installing a replacement, the stored curve no longer matches the new cell's actual voltage-versus-capacity profile, so percentage readings drift — often showing a full bar well into discharge, then dropping suddenly. The fix is a single full calibration cycle: charge to 100%, use the phone normally until it shuts off on its own, then charge back to 100% without interruption. After that cycle, the IC recalibrates to the new cell and percentage accuracy stabilises.