Technical Overview

The HHR-21AHF2A1 is a high-reliability Nickel-Metal Hydride (Ni-MH) backup battery assembly designed for Yokogawa Distributed Control Systems (DCS). It provides memory retention and real-time clock backup, ensuring configuration data and event logs are preserved during primary power loss.

Engineered for long service life and thermal stability, this battery is a critical preventive-maintenance component for maintaining system availability in industrial control environments.

Detailed Specifications

Application

• Memory backup for CPU modules

• Real-time clock retention in communication and control units

• Yokogawa CENTUM series and related DCS hardware

• Systems requiring safe, continuous trickle-charge backup power

Maintenance & Operational Notes

• Recommended replacement as part of preventive maintenance schedules

• Eliminates data loss and battery-low alarms after power interruptions

• Ni-MH chemistry avoids memory effect seen in older Ni-Cd batteries

• Compact form factor supports installation in high-density electronic modules

Technical FAQ

Can the HHR-21AHF2A1 be replaced while the system is running?
In most Yokogawa CPU modules, battery replacement is supported while powered (hot-swap). Always verify with the specific module manual before replacement.

Why is Ni-MH used instead of lithium batteries?
Ni-MH batteries offer a stable discharge profile and are safer for continuous trickle charging inside enclosed control modules compared to many lithium chemistries.

Is pre-charging required before installation?
No. The battery may ship partially charged, but the module’s internal charging circuit will automatically charge it to full capacity after installation.