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Battery Hierarchy for Emergency Power Supply

IP.com Disclosure Number: IPCOM000108724D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 3 page(s) / 156K

Publishing Venue

IBM

Related People

Garwin, RL: AUTHOR

Abstract

Disclosed is a less expensive, smaller, and more effective battery-operated emergency power supply system for computers or other equipment that must be kept running during power outages, change of power equipment, and the like.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 42% of the total text.

Battery Hierarchy for Emergency Power Supply

       Disclosed is a less expensive, smaller, and more
effective battery-operated emergency power supply system for
computers or other equipment that must be kept running during power
outages, change of power equipment, and the like.

      In general, interruptions of power of short duration are more
frequent than interruptions of very long duration; furthermore,
important measures to aid recovery can be taken during seconds or
minutes immediately following failure of normal power to make it less
important to continue operation on emergency power.

      However, it is normal to have only a single homogeneous type of
backup battery or power supply for a computer, whereas it is clear
that not only the need for but the character of backup power for the
first seconds or minutes is very different from the requirement on
the backup energy source that will handle the second 55 minutes or
hour or day.  The fact that one normally uses "more of the same" to
provide power for 305 minutes  or an hour as for the first 105
seconds or one minute increases the cost and reduces the reliability
of the backup power.

      Many large computer installations in the modern era do have
remote backups, which could take over after the period of transfer,
so that it is useful to provide means for reliably maintaining power
to a computer or other equipment for a finite time (we take, for
example, one hour), after which time some conventional auxiliary
power supply like a diesel engine might be used, or the equipment
would shut down after due warning.

      A common type of emergency backup power includes on-line banks
of lead-acid batteries (whether in liquid electrolyte or gel form),
but with all batteries of the backup supply essentially identical.
This means that the entire backup energy store must be maintained
charged.  This might be done by dividing the backup supply into banks
of cells, and having each bank connected to the supply bus through a
diode or other controller, so that it might be taken off line for
charging and then reconnected.  This allows better control over the
charging rate and state of charge of each bank than is possible if
all are charged or discharged together.

      But such "secondary cells" which can be used as a source of
electrical energy that is put in by electrical means tend to be
larger and more costly than primary cells which are fabricated by
chemical and mechanical means with electrodes of dissimilar
materials, and which provide power by the modification of electrode
material as current passes through the cell.

      Thus, if one were pretty sure that the long-duration
interruption would happen only once or not more than a couple of
times during the entire life of the equipment, the emergency supply
would be smaller (and indeed cheaper) if it were composed of primary
batteries rather than secondary cells.

      It is also true that primary ce...