Manta MS1701 Replacement Battery JB-4C 3.7V 750mAh

Manta MS1701 / TEL2405 / TEL2408 — 3.7V Li-ion Replacement Battery (JB-4C)

This is a 3.7V 750mAh Li-ion cell replacing part number JB-4C in the Manta MS1701, TEL2405, and TEL2408 smartphones. It fits all three handsets — same connector, same BMS handshake, same physical footprint at 53 × 34 × 4.80mm. Capacity is 750mAh (2.78Wh), matching the original specification.

• MS1701, TEL2405, TEL2408 compatibility: All three models share the JB-4C battery platform — identical voltage rail, connector pinout, and BMS communication protocol. One cell covers all three without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the MS1701 platform. The BMS accepted the new cell without fault codes, and the charge IC completed a full cycle to 4.2V termination without interruption.
• Fuel gauge recalibration on first cycle: After fitting this cell, disable fast charging if your handset supports it and run one complete discharge-charge cycle at standard rate. The fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle against the new cell lets it relearn the curve before it starts reporting accurate percentages.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC still holds the old cell's discharge curve in memory. The old cell had a gradual voltage slope at low charge — the new cell may have a steeper drop-off near the same state-of-charge point. Under modem or screen load, the new cell's voltage sags below the shutdown threshold before the gauge reads zero. One full discharge-charge cycle forces the coulomb counter to relearn the new cell's curve. After that cycle, the phone's cut-off behaviour should align with the actual remaining charge. If shutdowns persist past two full cycles, check that the termination voltage at charge-end is reaching 4.2V.

Phone will not power on after the battery sat in storage

Li-ion cells self-discharge in storage, and if the cell drops below approximately 2.5V the BMS enters lockout to prevent damage. In this state the phone shows nothing — no charging animation, no response. Connect the handset to a wall adapter rather than a PC USB port, which delivers consistent 5V at adequate current. Hold the power button for 10–15 seconds after connecting — some Manta firmware variants require this to kick the charge IC into recovery mode. If the screen still does not respond after 20 minutes on charge, disconnect, wait two minutes, then reconnect to allow the BMS to re-initialise.