6 Battery Gauging and Protection

It is critical to have a robust battery system with a gauge and protector that can not only enhance the safety of an ultrasound system, but also extend the run time and life-time of the battery pack. An authentication feature ensures a battery’s safe and authorized use, while a battery gauge with Impedance Track™ technology can directly measure the effect of the discharge rate, temperature, age and other factors by learning the cell impedance.

A battery gauge can provide an early warning of when a battery is nearing the end of its life; in a hospital setting, receiving such an early warning can help avoid patient casualties. Li-ion batteries are highly efficient, but battery failures do still occur. To operate safely and reliably, devices should offer accurate battery monitoring and provide thresholds for overcurrent protection during high discharge and charge current operation, as well as protection during battery overcharging and depleted conditions. The BQ40Z50-R2, one- to four-cell Li-ion battery-pack manager is an integrated, single-chip, pack-based solution that includes features for gas gauging, protection and authentication.

It is important to acknowledge the different components of a smart battery pack. A smart battery is a battery pack that comes with both an integrated gas gauge and an interface to enable the battery to communicate with a host device for the purposes of reading information on the battery’s state of charge, state of health, reason of protection, preferred method of charge and many other items. With a smart battery, there is no algorithm or calculation required by the host processor.