Acroprint ES900 9.6V Ni-MH Compatible Battery 2000mAh

Acroprint ES900 / ES1000 Series — 9.6V Ni-MH Replacement Battery (58-0108-000)

This 9.6V 2000mAh Ni-MH battery is the internal backup cell for the Acroprint ES900, ES1000, ATT310, and 175 Full Power Reserve time clocks. It keeps the real-time clock and attendance memory running during mains power interruptions. Without a working backup cell, the clock loses time and all stored punch data the moment power drops.

• ES900 / ES1000 / ATT310 platform fit: These models share the same 9.6V backup rail, connector pinout, and BMS handshake protocol. One battery services the full range without wiring modification.
• Bench tested on actual hardware: We cycled this cell through simulated power-cut events on the ES900. The BMS held the RTC and RAM without resetting, and voltage recovery after a full discharge returned to 9.6V nominal within one charge cycle.
• Data export before swap: Export all employee attendance records and enrollment data before removing the old battery. The ES900 stores punch records in battery-backed RAM — cutting all power, even briefly during a swap, wipes that data permanently. Back up via the RS-232 or USB port first.

Why the ES900 loses all employee data after a battery swap

The ES900 holds attendance records and employee enrollments in volatile RAM. That RAM stays live only as long as the backup battery supplies voltage above approximately 7.2V. Once the old battery is disconnected and the new one is not yet seated, RAM loses power entirely and all stored data is erased. This is not a fault in the replacement battery — it is the normal behaviour of the clock's memory architecture. The fix is to export records through the time clock's software before any physical battery work begins.

Clock showing incorrect time after power outage even with new battery installed

Some ES900 units use a separate coin-cell RTC circuit that runs independently of the main backup battery. If that coin cell is depleted, the main 9.6V pack keeps RAM alive but the real-time clock still drifts or resets. After fitting this replacement, check whether the displayed time holds correctly through a second power interruption. If it does not, the coin cell on the main board needs replacement — typically a CR2032 — before the clock will track time accurately.