Pantech PN-C520 Compatible Battery 3.7V 650mAh Li-ion

Pantech PN-C520 / Breeze — 3.7V Li-ion Replacement Battery (PBR-C520)

This is a 3.7V, 650mAh Li-ion cell replacement for the Pantech PN-C520, Breeze, and PC7300. It fits the original battery slot and connects to the same charge IC the phone uses from the factory. Capacity is 650mAh — identical to the OEM spec.

• PN-C520, Breeze, and PC7300 compatibility: These models share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. The BMS handshake uses the same thermistor line across all three, so the charge IC accepts this cell without prompting a fault condition.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a PN-C520 unit. The BMS accepted the cell on the first connection, the charge IC moved through trickle, bulk, and top-off phases without interruption, and the fuel gauge registered a full state of charge at completion.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. The fuel gauge IC on the PN-C520 is calibrated to the discharge curve of the old cell — one full cycle lets it recalibrate against the new cell before reporting accurate percentages.

Sudden shutdown at 20–30% on the PN-C520 after a cell swap

This happens because the fuel gauge IC is still using the discharge curve mapped to the old cell. When the phone reads 20–30% remaining, the new cell may already be sitting at a voltage the phone treats as critically low under modem or screen load. The processor triggers a protection shutdown before the percentage reaches zero. One full discharge-charge cycle rewrites the coulomb counter's reference points and clears this behaviour.

Phone warm near the battery compartment during the first charge

A new Li-ion cell arrives with higher internal impedance than a broken-in cell. During the first bulk charge phase, the charge IC pushes current into a cell that hasn't settled to its operating impedance yet — this produces mild heat near the battery bay. It is normal for the first one or two cycles. If warmth persists beyond the second full charge, check that the phone's charge IC is not stuck in bulk phase by confirming the cell reaches 4.2V and the charging indicator clears.