ams has developed a reference design which shows how a simple current and voltage measurement circuit can produce state of charge readings for electric scooter batteries. The reference design uses the AS8510 sensor interface from ams, a two-channel battery sensor interface, together with a simple 8-bit microcontroller, an LDO and an LED driver (driving an LED bar-graph display). The new e-scooter fuel-gauging reference design from ams succeeds in meeting the tight cost requirements of electric scooter manufacturers while delivering accurate voltage and current readings across the charge/discharge cycle and across the battery's operating temperature range. This is due in large part to the circuit's use of the AS8510 sensor interface, which integrates data acquisition and data conversion in a single chip, and which produces virtually offset-free current and voltage measurements across a wide, dynamic range.
The ams circuit design captures simultaneous current and voltage measurements for each of the four batteries at a high sampling rate. Demonstration software implemented in an 8-bit microcontroller converts a combination of open-circuit voltage measurements and coulomb counts into SOC readings. The reference design supports a simple LED bar graph display, but it can also be used to drive a more expensive LCD display, providing more precise SOC information to the rider. The reference design is available free to ams customers.