Browse Prior Art Database

Battery Charging and Discharging Circuit for Portable Devices

IP.com Disclosure Number: IPCOM000112791D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Concha, F: AUTHOR [+2]

Abstract

Disclosed is an electronic circuit for monitoring the temperature of a battery within a device and for adjusting the charge and discharge rates to provide maximum utilization of the device while maintaining safe conditions at the battery and the device. This circuit is especially useful when it is applied within a device used where wide variations in temperature are typically encountered, such as a device stored, recharged, and used within a vehicle, and also used outside the vehicle.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Battery Charging and Discharging Circuit for Portable Devices

      Disclosed is an electronic circuit for monitoring the
temperature of a battery within a device and for adjusting the charge
and discharge rates to provide maximum utilization of the device
while maintaining safe conditions at the battery and the device.
This circuit is especially useful when it is applied within a device
used where wide variations in temperature are typically encountered,
such as a device stored, recharged, and used within a vehicle, and
also used outside the vehicle.

      Fig. 1 shows a circuit used to monitor battery temperature and
to control the cycle time for both charge and discharge modes in
response to temperature variations.  Fig. 2 shows a typical
relationship between battery temperature and a charging or
discharging duty cycle, established using the circuit of Fig. 1.

      Referring first to Fig. 1, a battery compartment 10 includes a
battery 12 and a pair of thermistors 14 and 16.  Conventional
circuits for voltage sensing and current limiting, used with this
circuit, are not depicted.  First thermistor 14 is of a type having a
resistance decreasing with an increase in temperature, while second
thermistor 16 is of a type having a resistance increasing with an
increase in temperature.  Capacitors 18 and 19 are timing capacitors
used with thermistors 14 and 16 to establish the resistive and
capacitive timing values for the timing (T) inputs of monostable
multivibrators 20 and 22, which are connected to form a free-running
clocking circuit.  The timing input of first multivibrator 20 is
connected to a positive voltage through thermistor 14 and to a
negative voltage through capacitor 18, while the timing input of
second multivibrator 22 is connected to a positive voltage through
thermistor 16 and to a negative voltage through capacitor 19.  The
(Q1) output of first multivibrator 20 provides an active high control
signal used to control t...