Project: EV Battery

Lithium battery charge and discharge controller

A solution was adopted to use fibre-optical instead of electrical wiring between the units. This made the system far less prone to electrical noise and galvanically separated the cells.

The system has a 4 line, 20 character display, a battery backed-up real time clock / calendar, and 2 CAN bus interfaces. One for the charger and one to communicate with the car.

All measured data can be stored on a FAT32 micro-SD Card for easy data analysis using a PC.

The battery pack will be charged with the maximum current of the charger until the first cell reaches its maximum voltage. then the current will be tapered off step by step.

After the current has reached zero the balancing algorithm will equalize all cells. The balancing method uses switch-mode power supply method to move energy of full cells in to cells that are not full yet.

When cells are equalized, the charger will top the whole pack up again.

See pictures of the hardware with optical communication:

The PC based Graphical user interface (GUI) to test messages to and from the battery management system.