A logistics yard reported that a Baoli EPD15 electric forklift would suddenly stop moving. The "Trac" (traction) contactor under the seat would rapidly click (chatter), and the machine would not move until it was restarted. It happened most frequently on ramps.
The technician connected a "DC Clamp Meter" to the battery positive cable. When the operator pressed the accelerator, the current spiked to 400A, and the voltage dropped from 48V to 38V, causing the inverter controller to trigger a "Low Voltage Alarm" and disconnect the contactor. He inspected the "Battery Connectors." The "Anderson Connector" terminals were blue and corroded due to moisture ingress. The corrosion created high resistance, causing the voltage drop.
However, the chattering continued even after cleaning the connectors. He traced the "Phase Cables" to the "Traction Motor." The brass terminal lugs connecting the cables to the motor windings were loose and had arc-welded themselves to the terminal studs. The loose connection caused the AC inverter to receive fluctuating current feedback, leading to the contactor chattering.
The repair involved cutting the damaged terminal lugs off the phase cables and crimping new, heavy-duty tinned copper lugs. The motor terminal studs were cleaned, and the nuts were torqued to spec. The Anderson connector was replaced. The forklift then pulled hard up ramps without any voltage sag or contactor interruption.
