About this replacement
Sagem Puma Phone — 3.7V Li-ion Replacement Battery (LS2M 142/10)
This 3.7V 850mAh Li-ion cell is a direct replacement for the Sagem Puma Phone and P-Phone. It slots into the same battery bay as the original and connects to the same charge IC and fuel gauge circuit. If your Puma Phone won't hold a charge or shuts down unexpectedly, this is the cell to swap.
- Puma Phone and P-Phone platform fit: Both the Puma Phone and P-Phone share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The same 3.7V cell services both variants without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Puma Phone platform. The BMS accepted the cell on first connection, charge termination triggered correctly at 4.2V, and the protection circuit cut off cleanly at low-voltage threshold.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-charge cycle before resuming normal use. The phone's fuel gauge IC is still calibrated to the old cell's discharge curve. One complete cycle lets it remap against the new cell and report accurate percentages.
Sudden shutdown at 20–30% on the Puma Phone after a cell swap
This happens because the fuel gauge IC inherited its discharge curve model from the original cell. A new cell with a different internal resistance profile hits a voltage cliff earlier than the old model predicts — the phone reads 25% but the actual cell voltage under modem or screen load drops below 3.4V, triggering an emergency shutdown. It is not a fault in the replacement cell. Run two full discharge-charge cycles without interruption and the fuel gauge will remap its model against the real discharge curve of the new cell.
Puma Phone not powering on after the battery sat in storage
Li-ion cells self-discharge in storage. If the cell dropped below 2.5V, the BMS enters lockout mode and blocks charge input to prevent damage to an over-discharged cell. The phone shows nothing when plugged in — no charging icon, no boot screen. Connect to a charger and leave it for 20–30 minutes without pressing the power button. Most BMS circuits include a trickle pre-charge path that slowly raises cell voltage from as low as 2.0V. Once the cell clears 3.0V, the BMS releases the lockout and normal charging resumes.