Smart battery charger

Many laptop computers have an internal smart battery charging system and use smart batteries.

A smart battery charger is mainly a switch mode power supply (also known as high frequency charger) that has the ability to communicate with a smart battery pack's battery management system (BMS) in order to control and monitor the charging process.^[1] This communication may be by a standard bus such as CAN bus in automobiles or System Management Bus (SMBus) in computers. The charge process is controlled by the BMS and not by the charger, thus increasing security in the system. Not all chargers have this type of communication which is commonly used for lithium batteries.

Besides the usual plus (positive) and minus (negative) terminals, a smart battery charger also has multiple terminals to connect to the smart battery pack's BMS. The Smart Battery System standard is commonly used to define this connection, which includes the data bus and the communications protocol between the charger and battery. There are other ad-hoc specifications also used.

Hardware

Smart battery controller integrated circuits are available. For example, Linear Technology manufactures the LTC4100^[2] and the LTC4101^[3] Smart Battery System-compatible products.

Microchip Technology provides an application note for a smart battery charger based on the PIC16C73.^[4] The PIC16C73 source code is available for this application.

References