Bolt Battery Monitoring
With the use of the Bolt Battery there is no need to bottom balance the cells within the module. The batteries come from the factory perfectly balanced and the way the cells are wired, individual cells are not likely to change voltage relative to other cells in the module. Below is a screen shot of the Multicell Monitor demo software that comes with the demo BMS board. The software displays the voltage of every cell. You can see the cells are all within +/-1mV of each other. A survey of the 9 Bolt Battery modules found all 90 cells to be within +/-2mV. The software also can turn on the tuning function, which can discharge each cell individually, if needed. The board has 12 channels to measure a mulitcell battery like the Bolt Battery. But on the Bolt Battery there are only 10 cells. To use the BMS demo board the 6th and 12th connections are shorted to the adjacent inputs. This is just a consequence to the internal wiring of the ADC. All of the functions and measurements shown on this GUI are available with a Arduino sketch that Analog Devices also supplies with the BMS demo board. Analog makes a Arduino board equivalent to the Arduino Uno board called the Linduino and a shield, DC2792B that has Isolated SPI (isoSPI) communication. Up to 5 BMS demo boards can be connected via the isoSPI. The Analog Devices web page with these boards can be found here. A look at that the BMS demo board with the Linduino is shown below the screen shot. The BMS demo board can be connected via the 14 pin ribbon cable to the Linduino for demo purposes, but the way the BMS demo boards will be connected in the car is with the RJ45 connectors on the end of the board that are for the isoSPI connection. See the page on Battery Maintenance System for more details on the isoSPI connections.