CAN stands for Controller Area Network, which is a protocol adopted by the auto industry to allow micro-controllers and other devices in a vehicle to communicate with each other. Shown above is a CAN adapter sold by Ewert Energy Systems that lets the Orion BMS communicate with a computer. Data flows from the Orion’s CAN bus through the adapter to the USB port of a laptop, where the Orion BMS Utility displays real-time cell voltage, state-of-charge, internal resistance, pack voltage, current, and a variety of other data sets.
More importantly, the utility can be used to program the Orion’s charger control settings, maximum and minimum voltages, current levels, battery profiles, cell-balancing settings, and many other parameters that allow detailed control and monitoring of a battery pack.
The Orion provides two CAN ports to allow multiple devices to communicate with the BMS simultaneously, with each CAN circuit consisting of three connections: CAN high, CAN low, and a shield. The CANdapter shown above at center left will communicate on CAN1 via the DB9 connector on its top end. Its CAN high lead is connected to pin #3, and CAN low to pin #5. CAN1 is already terminated inside the Orion, so only one external 120 ohm resistor is needed across the CAN leads at the DB9 connector. The Orion will use CAN1 to interface with my MacBook via the USB cable seen above, providing a way to change BMS settings and update firmware.
Also shown at center right is the PLX Kiwi Bluetooth module, which will use CAN2 to transmit cell and pack data to a touchscreen that will be installed in the center console. The Kiwi talks to the Orion via an OBD-II connector, which is a standard On Board Diagnostic data port for all cars made after 1996. CAN high is connected to OBD pin #6, CAN low to pin #14, chassis ground to pins #4 and #5, and 12 volt accessory power to pin #16.
The shielding wires on both CAN pairs should also be connected to chassis ground to eliminate any extraneous electrical noise that could interfere with clean data transmission.
In order to see the CANdapter on the USB port of a PC or Mac, you’ll need to install specific USB device drivers. Next, plug in the CANdapter and put the BMS either in Charge or Ready mode so that it’s visible to the Orion BMS Utility. Then use the FILE pull-down menu to connect the utility to the Orion. Once successfully mounted, all of the tabs across the top of the window become active, and the utility is ready to start processing pack data. My first step is to populate the cell table using the setup wizard, which offers many different brand names, capacities, and quantities of cells. I chose 36 CALB (blue) 180 Ah cells to correctly match my pack.
Once the charger brings the pack to a preset upper voltage, the Orion then sets about top-balancing the cells by slowly draining them to match the level of those least charged. It does this even after the BMS has turned the charger off. As seen above, live data on cells that are balancing are indicated in red. Since this is their first charge with the Orion, most all of the cells are being balanced except the two lowest. I was informed by Ewert that the pack balance will tighten up after multiple charge cycles. From then on, the only reason to break out the laptop is to periodically check pack health, and to install firmware updates.
*NOTE – Among the multitude of data, I was happy to discover that none of my cells were suspiciously undercharged, all internal resistances were normal, and the pack State of Health was reported at 100%. What a great relief to know that all my cells had dodged the fatal bullet of deep discharge.
Adding to the excitement, my Android phone paired perfectly to the Kiwi, giving me access to BMS/pack data without a laptop. That’s vital out on the road, where it counts. There are several apps that allow users to access and display OBD data from any vehicle using either USB or a Bluetooth device like the Kiwi. The above Android app is called Torque, and works cleanly with the Orion BMS due to its flexible OBD support. I chose the EV gauges above from a drop-down menu after loading the extended PID (parameter ID) file into the Torque folder on my phone. The Orion website offers instructions to coach you through this. Once loaded and locked to the BMS, Torque displays real-time pack data, with valuable logging and graphing functions. The above image is a screenshot from my drive into work this AM.
More blogposting about Torque here. Next up: Picking out a 7 inch touchscreen tablet!