UTStarcom 6800 Compatible Battery 3.7V 1250mAh 35H00077-00M

UTStarcom PPC6800 / VX6800 — 3.7V Li-Polymer Replacement Battery (35H00077-00M)

This 3.7V 1250mAh lithium-polymer cell replaces the original battery in the UTStarcom 6800, PPC6800, PPC-6800, and VX6800 Windows Mobile PDA phones. It matches the OEM footprint at 66.50 × 44.00 × 4.50mm and connects directly to the stock charge circuit. Rated at 4.63Wh — identical to the original specification.

• 6800 and PPC-6800 platform fit: All four model variants — 6800, PPC6800, PPC-6800, and VX6800 — share the same battery bay dimensions, connector pinout, and charge IC. One cell covers the full range without adapter or modification.
• Bench tested on actual hardware: We cycled this cell through full charge and load discharge on the 6800 platform. The BMS accepted the charge protocol without fault flags, and voltage held steady across combined modem and display loads.
• Fuel gauge recalibration on first install: On first use, disable any push sync or background data tasks and run one complete discharge down to auto-shutoff, then charge uninterrupted to 100%. This gives the coulomb counter a clean reference cycle against the new cell's actual discharge curve before normal use resumes.

Sudden shutdown at 20–30% on the PPC-6800 after a cell swap

The 6800's fuel gauge IC builds its percentage estimate from a discharge curve stored during previous cycles on the old cell. A new lithium-polymer cell has a steeper voltage cliff near the low end — the phone's threshold voltage hits before the gauge reaches zero. Under combined GSM radio and backlight load, voltage drops fast enough to trigger a hard cutoff even when the displayed percentage looks safe. One full calibration cycle — full discharge to shutoff, then full uninterrupted charge — rewrites the curve and stops the early cutoffs.

Phone warm near the battery compartment during the first charge

A fresh lithium-polymer cell starts with slightly higher internal impedance than a broken-in cell. The 6800's charge IC pushes constant current into that higher impedance, which generates more heat during the first one or two charge cycles than you'd see later. This is normal and self-correcting — impedance drops as the cell cycles. If the case stays warm beyond the second full charge, check that the back cover is seated flat and not trapping heat against the battery surface.