Symbol VRC6900 Replacement Battery 8.4V 230mAh Ni-MH

Symbol VRC6900 Series — 8.4V Ni-MH CMOS Backup Battery (69XXSY3000)

This is an 8.4V 230mAh Ni-MH CMOS backup battery for the Symbol VRC6900, VRC6940, and VRC6946 mobile computers. It maintains the real-time clock and system settings when the primary battery is removed or the unit sits in extended storage. Without a functioning CMOS cell, the device loses its clock, regional settings, and any stored configuration on every power interruption.

• VRC6900, VRC6940, VRC6946 compatibility: These three models share the same internal CMOS circuit and use the same OEM part number 69XXSY3000. The voltage rail, connector footprint, and BMS handshake are identical across the series — one cell fits all three.
• Bench tested on actual hardware: We ran this cell against the CMOS retention circuit and confirmed stable voltage above the 2.8V minimum threshold required to hold SRAM state and keep the RTC ticking through primary battery swaps.
• Clock correction after install: After fitting the new cell, power on the VRC6900 and manually set the correct date and time through the device settings. The CMOS cell powers the RTC circuit directly — any interruption during the swap resets the clock to its factory default, and it will not self-correct.

Why the VRC6900 clock resets to a default date after every power cycle

The RTC circuit on the VRC6900 draws its standby power from the CMOS backup cell, not the main battery pack. When the CMOS cell drops below 2.8V, it can no longer sustain the SRAM state or keep the oscillator running. The clock resets to a hardcoded default — typically a date from the firmware build — every time mains or primary power is removed. Replacing the 69XXSY3000 cell and resetting the clock through device settings resolves this.

CMOS checksum error appearing on VRC6900 boot screen

A checksum error on boot means the CMOS cell has fully depleted and the stored settings — including clock, regional config, and scanner parameters — have been wiped. The device recalculates the checksum on startup and flags the mismatch because the current values no longer match what was saved. This is a different symptom from a slow clock drift; the cell is completely dead, not just low. Replace the backup cell, then re-enter all device settings and confirm the RTC holds across a full power cycle.