Backup battery

Backup batteries range from small single cells to retain clock time and date in computers, up to large battery room facilities that power uninterruptible power supply systems for large data centers.

Backup batteries in aircraft keep essential instruments and devices running in the event of an engine power failure.

Modern personal computer motherboards have a backup battery to run the real-time clock circuit and retain configuration memory while the system is turned off.

The original IBM AT through to the PS/2 range, used a relatively large primary lithium battery, compared to later models, to retain the clock and configuration memory.

[2] These early machines required the backup battery to be replaced periodically due to the relatively large power consumption.

If this battery is present, disk writes can be considered completed when they reach the cache, thus speeding up I/O throughput by not waiting for the hard drive.

A local backup battery unit is necessary in some telephony and combined telephony/data applications built with use of digital passive optical networks.

VRLA batteries are used in the outside plant at locations such as Controlled Environmental Vaults (CEVs), Electronic Equipment Enclosures (EEEs), and huts, and in uncontrolled structures such as cabinets.

The compliance system provides a common framework for evaluating and qualifying various valve-regulated lead-acid battery technologies.

Tesla, Inc installed the world's largest lithium ion battery pack for the government of South Australia in 2017; to help alleviate energy (electricity) blackouts in the state.