Lift device and method of controlling

A lift device comprising:

• a chassis;
• a plurality of traction devices to support the chassis on an underlying surface;
• an electric propulsion system comprising:
• an electric motor drivingly coupled to at least one of the plurality of traction devices,
• a motor controller in electrical communication with the electric motor, and
• a traction battery in electrical communication with the electric motor via the motor controller;
• a hydraulic circuit with a pump, a pressure galley, a return line, and a valve controlling pressure in the pressure galley and fluidly connecting the pressure galley to the return line;
• a pump motor drivingly connected to the pump and in electrical communication with the traction battery;
• a user input to control a speed of the lift device;
• and
• a controller configured to, in response to a temperature of the traction battery being outside a predetermined range when the electric motor is commanded to output a braking torque, command an increase of pressure in the pressure galley to reduce electrical power to the traction battery and limit charging of the battery via:
• (i) control of the pump to increase a flow of the pump, and/or (ii) control of the valve to reduce a size of the valve opening.

A method of controlling a lift device comprising:

• propelling the lift device via an electric propulsion system, the electric propulsion system comprising a traction battery electrically connected to at least one electric motor via a motor controller, wherein the at least one electric motor connected to a wheel;
• providing a hydraulic circuit with a pump providing flow to a pressure galley, a valve fluidly connecting the pressure galley to a return line, and an actuator in fluid communication with the pressure galley and the return line;
• driving the pump with a pump motor electrically connected to the traction battery;
• determining a braking power output for the at least one electric motor to control the lift device to a commanded speed based on an actual speed of the lift device and a load on the electric motors;
• and
• in response to the braking power output being greater than a threshold, increasing a flow of the pump and/or controlling the valve to reduce a size of an opening of the valve thereby dissipating braking power output above the threshold into a hydraulic circuit and charging the traction battery with the remaining braking power output.