Typical Manifestations of Inadequate Preheating of Indoor Electric Forklifts

I. Power System: Sudden ｄｒｏｐ in Endurance + Unstable Power Output

Weak Starting/Acceleration

• After the power is turned on, the voltage displayed on the dashboard is normal, but when the accelerator pedal is lightly pressed, the forklift starts slowly and its climbing ability is significantly reduced (even empty-load climbing feels stuck).
• When under heavy load (≥50% of the rated load), there may even be a "no response when stepping on the accelerator" or power interruption, which is more prominent in low-temperature environments.

Cliff-like ｄｒｏｐ in Battery Endurance

• Inadequate preheating will aggravate the low-temperature polarization effect of the battery, resulting in the actual endurance being only 50%–70% of the normal state.
• "False power" frequently occurs during operation, with severe fluctuations in the voltage pointer. The voltage is normal when unloaded, but drops rapidly once loaded, and may even trigger low-power protection and shutdown.

Poor Charging Acceptance

• Directly charging a battery with insufficient preheating will result in a charging time prolonged by more than 30% and failure to fully charge.
• Lead-acid batteries may also experience accelerated plate sulfation, characterized by premature bubbling during charging and rapid voltage ｄｒｏｐ during discharging.

II. Hydraulic System: Hysteretic Action + Abnormal Noise and Leakage

Stuck Fork Lifting/Lowering and Mast Tilting

• When operating the lifting handle, the fork lifting/lowering speed is extremely slow, and there may even be a situation where "it stops halfway when lifting". The mast forward/backward tilting action is hysteretic, with a response delay of 2–3 seconds (≤0.5 seconds under normal conditions).
• Low-temperature hydraulic oil has high viscosity, resulting in slow system pressure rise. When under heavy load (≥70% of the rated load), lifting may be completely impossible.

Obvious Abnormal Noise in the Hydraulic System

• The hydraulic pump emits abnormal "buzzing" noise due to viscous oil and excessive load, and may even produce sharp "whistling" sounds.
• Slight vibration may occur at pipeline joints due to pressure fluctuations, accompanied by hydraulic oil leakage (seals harden and sealing performance decreases at low temperatures).

Abnormal Rise in Hydraulic Oil Temperature

• Direct heavy-load operation without adequate preheating leads to high flow resistance of hydraulic oil in pipelines and intensified frictional heating. The oil temperature exceeds 60℃ after 10–15 minutes of operation (the normal operating oil temperature should be ≤55℃), triggering an over-temperature alarm.

III. Braking and Steering System: Deteriorated Operating Feel + Increased Safety Risks

Degraded Braking Performance

• The brake pedal feels stiff with high resistance when pressed. The braking distance is significantly extended: when the empty forklift travels at 5km/h, the braking distance exceeds 4m (≤3m under normal conditions).
• The viscosity of brake fluid increases at low temperatures, and "vapor lock" may occur in the brake pipeline, characterized by an increasingly longer pedal stroke and deteriorating braking effect when stepping on the brake continuously.

Heavy and Stuck Steering

• The steering wheel has high turning resistance, especially when turning at low speeds, requiring more force to turn.
• Insufficient hydraulic power assistance in the steering system leads to "stuck points" during steering and unsmooth return to center, which is likely to cause the forklift to deviate during driving.

IV. Electrical System: Intermittent Failures + Frequent Alarms

Flashing Dashboard Warning Lights

• Due to battery voltage fluctuations and reduced line insulation, the power fault light and battery fault light on the dashboard may flash frequently, but the alarm disappears after the forklift is shut down and left standing for a while (a typical intermittent failure caused by inadequate preheating).

Poor Engagement of Contactors/Relays

• The contacts of electrical components produce "sizzling" abnormal noise when engaging due to low-temperature oxidation and condensation effects, and may even cause frequent power cuts and restarts.
• Auxiliary electrical appliances such as lights and horns may work intermittently.

V. Comparison Table of Abnormal Manifestations in Different Temperature Ranges

VI. Quick Judgment Skills

1. 1.Continuously lift and lower the empty fork 3 times. If the action is smooth without sticking → preheating is qualified; if the lifting/lowering speed becomes slower and slower → preheating is insufficient.
2. 2.Drive straight at low speed for 10m and lightly step on the brake pedal. If the braking is sensitive without deviation → preheating is qualified; if the brake feels stiff and the braking distance is too long → preheating is insufficient.
3. 3.Observe the dashboard voltage. When loaded (e.g., lifting an empty fork), if the voltage fluctuation is ≤0.5V → preheating is qualified; if the fluctuation is ≥1V → preheating is insufficient