User`s guide

6-4 Intel
®
StrongARM
®
SA-1110 Microprocessor Development Board User’s Guide
System Power Management
An added complication with sophisticated battery management systems and Li-ion batteries is the
possibility of battery fires or explosions caused by flawed hardware or software design or computer
viruses.
6.2.6 Fuel Gauging
Fuel gauging or gas gauging refers to the hardware and software techniques that attempt to
maintain an accurate accounting of the remaining battery capacity. In the past these attempts have
proved very inaccurate. Intel is a prime sponsor of the Smart Battery Systems (SBS) initiative that
includes micro-controllers that can sense and store battery information. A goal of better than 20%
accuracy is desired to provide useful information to the users.
Several key parameters affect accurate fuel gauging.
• Battery chemistry
• Battery capacity
• Battery age and history
• Battery temperature
• Battery terminal voltage
• Discharge current
• Charge current
The SBS specifies a System Management Bus (SMBus) for communicating with the battery
management controllers. The SMBus is a subset of the I
2
C* bus protocol that can be supported
using SA-1110 GPIO pins.
Benchmarq Products supplied some of the first SBS v1.0 compatible battery management
components. Benchmarq Products supplies both devices as well as small boards intended for
integration inside battery packs. The SA-1110 Development Board may optionally use a 0.25” by
3.5” battery management board attached directly to the batteries. To accurately register battery
temperature the battery management ICs are in close proximity to the batteries. Battery
temperature is a critical parameter for accurate fuel gauging and battery safety. The use of a
separate battery management board allows the development and evaluation of alternate vendor
battery management boards. The interface to the batteries and battery management boards is
through a simple header that provides power ground and SMBus connections.
SBS battery management ICs provide non-volatile storage of many critical battery statistics such as
the following parameters:
• Battery pack serial number
• Battery temperature
• Remaining charge
• Instantaneous current
• Total life time charge
• Total lifetime discharge
• Time