Oracle Tablet 720 PT352044 Replacement CMOS Battery 3.7V 250mAh

Oracle Tablet 720 / Tablet 721 — 3.7V Li-Polymer Replacement Battery (PT352044)

This 3.7V, 250mAh lithium-polymer cell replaces the CMOS backup battery in the Oracle Tablet 720 and Tablet 721. It maintains the real-time clock (RTC) and stored system settings when mains power is removed. When this cell depletes, the device loses configuration data and the clock resets to a default date on every power cycle.

• Tablet 720 and Tablet 721 compatibility: Both models use the same RTC circuit backed by a single lithium-polymer cell at 3.7V nominal. The PT352044 part number covers both variants — the connector, cell dimensions (41.60 × 20.14 × 4.30mm), and voltage rail are identical across both units.
• Bench tested on actual hardware: We ran this cell against the PT352044 specification and confirmed stable voltage output across the SRAM retention circuit. The cell held above the 2.8V minimum retention threshold required to prevent a CMOS reset event.
• Post-installation clock correction: After fitting this cell, enter the system setup menu and manually set the correct date and time, then save and exit. The RTC circuit loses its reference when the old cell is removed, and the clock defaults to a fixed value until corrected. Skip this step and the device will boot with a wrong timestamp on every cycle.

BIOS clock resetting to a default date after every power cycle

The RTC on the Oracle Tablet 720 is backed solely by this CMOS cell. When the cell drops below 2.8V, the SRAM holding the clock value can no longer retain data. Each time mains power is removed, the RTC loses its timestamp and reverts to a factory default — often January 1, 2000 or a similar fixed date. Replacing the cell and setting the correct date in the system setup menu resolves this immediately. Confirm the new cell reads at or above 3.0V before installation.

CMOS checksum error on boot after the old cell was removed

A checksum error at boot means the CMOS data has already been corrupted — the cell was fully depleted before or during the swap. The system detects that stored values no longer match the checksum and flags the error. Installing a fresh PT352044 cell restores power to the CMOS circuit, but the error will persist until you enter system setup, re-enter all settings, and save. The checksum recalculates on a clean save and the error clears on the next boot.