Controller Batteries

HP 235870-001 EVA3000 EVA5000 Storage Controller Battery 70-40818-01

372538-B21 HP 512MB DDR Battery Backed Write Cache 372538-B21

46C8872 IBM DS5100 DS5300 Controller Battery

This is a lithium-ion battery pack that serves as the backup power source for the storage controller's onboard NVRAM/write cache during power loss, controller failure, or system shutdown. It ensures that in-flight write data is preserved and safely destaged to disk (or mirrored to the partner controller in dual-controller HA setups), preventing data corruption or loss.

Battery type: Lithium-ion (Li-ion), typically 2-cell
Voltage: 6.6V–7.3V nominal (most listings specify 6.6V or 7.3V)
Capacity: 6.93Wh / 1.05Ah (common spec; some aftermarket variants list 14.9Wh equivalents)
Form factor: Compact rectangular pack with mounting clips and proprietary connector for direct insertion into the controller module (Type 15/18/19)
Purpose: Battery-backed write cache protection (similar to NVRAM batteries in other storage arrays like 3PAR, EVA, or VNX)

It is a very common maintenance item in EqualLogic PS series arrays — batteries typically last 3–5 years before capacity drops trigger alerts or automatic shutdowns to protect data. Dell firmware monitors battery health and raises warnings via EqualLogic Group Manager or SAN Headquarters (e.g., "battery nearing end of life," "capacity low," "current high").

DELL GP6RN Perc H740P 8GB Mini Mono 12G Raid Controller