Why Does A Diesel Forklift Still Need A Battery?

A diesel forklift uses fuel to produce the power that moves the truck, so buyers sometimes wonder:

Why does it still need a battery?

The answer is that the battery does not drive the forklift in the same way as the traction battery on an electric forklift.

Instead, it forms part of the diesel engine's starting and electrical system.

Before a diesel engine can run by itself, the crankshaft needs to begin turning.

When the operator turns the key or activates the start control, the battery supplies electrical current to the starter motor.

The starter motor cranks the engine until combustion begins and the diesel engine can continue running on its own.

This means a diesel forklift with a weak or discharged starting battery may have difficulty starting even when the fuel tank is full and the engine itself has no mechanical problem.

Once the diesel engine is running, the alternator generates electrical power.

Its two main jobs are to:

• recharge the starting battery
• supply electricity to the truck's electrical systems

This starting-and-charging arrangement is common on diesel-powered industrial equipment. Caterpillar, for example, describes the alternator as supplying electrical power while the engine runs and recharging the battery.

Depending on the forklift configuration, electrical power may also be required for:

• instrument display
• headlights and work lights
• horn
• warning beacon
• reverse alarm
• windshield wiper
• cameras or monitors
• control relays and solenoids
• engine electronic controls, where fitted

This is why the electrical system remains important even though the forklift's main source of operating power is diesel fuel.

These two types of batteries perform very different jobs.

An electric forklift traction battery provides the energy used to drive the truck and operate its hydraulic system.

A diesel forklift starting battery mainly supports engine starting and onboard electrical equipment.

For buyers comparing diesel and electric forklifts, this distinction is useful because battery capacity should not be interpreted in the same way on both types of machine.

Starting places a high electrical demand on the battery, especially when the engine is cold.

Battery condition, cable connections and charging performance therefore need to be checked during normal maintenance.

If a diesel forklift repeatedly becomes difficult to start, the problem should not automatically be blamed on the engine. The battery, starter circuit and charging system should also be inspected.

At Propolift, the diesel engine, starting system and electrical equipment are checked as part of the complete forklift configuration before delivery.

For buyers, the main point is simple:

diesel fuel provides the machine's operating power, but the battery provides the electrical energy needed to start the engine and support the forklift's electrical systems.

That is why even a large heavy duty diesel forklift still needs a healthy starting battery.