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Browse Prior Art Database

Battery Self-Discharge Management System

IP.com Disclosure Number: IPCOM000114197D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Mito, T: AUTHOR [+3]

Abstract

Disclosed is a battery capacity monitor system which controls battery self-discharge calculation. In general, rechargeable battery such as NiMH battery has the property of self-discharge. Therefore, if a battery capacity monitor system indicates percentage of true remaining capacity, the user may confuse since its capacity will be smaller than the user may have expected because it decreases by self-discharge. Especially, in case that the battery had been fully charged and then left alone for a while, the capacity monitor system causes this problem because the user thinks the battery is full but the system won't indicate 100% capacity. This invention is to evade the confusion.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Battery Self-Discharge Management System

      Disclosed is a battery capacity monitor system which controls
battery self-discharge calculation.  In general, rechargeable battery
such as NiMH battery has the property of self-discharge.  Therefore,
if a battery capacity monitor system indicates percentage of true
remaining capacity, the user may confuse since its capacity will be
smaller than the user may have expected because it decreases by
self-discharge.  Especially, in case that the battery had been fully
charged and then left alone for a while, the capacity monitor system
causes this problem because the user thinks the battery is full but
the system won't indicate 100% capacity.  This invention is to evade
the confusion.

      Table 1 shows an example of a conventional battery capacity
monitor system.  As shown, the battery capacity changes momentarily
after completing charged.  You may assume by Table 1 that battery
total capacity is 3300mAH, battery self-discharge rate is 10mAH/h,
and the battery isn't used.  When 12 hours has passed, the system
shows 96% (3180/3300) capacity.  The conventional system indicates
percentage only.  Therefore, the user doesn't understand why battery
capacity is reduced while the battery isn't used.

      On the other hand, Table 2 shows an example of the subject
battery capacity monitor system.  The above assumptions are the same
as above normal system.  In calculating the battery capacity, the
system subtracts b...