Using a SevCon motor controller with an Lithiumate BMS.
WARNING: SHOCK DANGER
The SevCon motor controllers do not provide isolation between the high voltage battery and the low voltage circuits.
Interfacing a SevCon motor controller and the Lithiumate BMS, no CAN bus
The DCL line from the Lithiumate normally sits at 5 V; when the battery is close to empty, it starts going down.
The diode clamps the maximum voltage across the throttle pot, so, as the battery gets more and more discharged, there is less and less available range in the throttle pot, and therefore the torque is limited, giving the driver feedback that there isn't much energy left.
The LLIM line is normally grounded (its polarity is flipped from the default) and is the common for the forward and reverse switches. Should the pack go empty, the LLIM line is opened, removing the drive to the forward and reverse switches, shutting down the SevCon.
While the Sevcon PowerPack motor driver has a CAN bus connector, it is not possible to control the driver through its CAN bus; therefore, there is no point in connecting it to a CAN bus, to the Lithiumate BMS.