Understanding Kubota Tractor Power System

Understand the easy-to-understand Kubota Tractor Power System

Many people understand that once the engine is attached, the entire electrical system is powered by the battery alone, but in fact, the tractor's electrical system works more complicated than that, and there is a battery-dicharger interplay.

Before starting the engine.

When the key is twisted to the ON or ST (Start) position, the only power supply is a 12-volt battery, which powers the dial, relay, control box (if any), and starter motor to turn the engine on.

The back of the engine is stuck.

When the engine starts, it rotates the belt to keep the dicharger running and produces a voltage of about 13.8-14.5 volts.

Because the dicharger voltage is higher than the battery voltage, current flows from the dicharger directly to the vehicle's electrical system, along with recharging the battery at the same time.

So while the engine is running, the dicharger is the main power supply of the electrical system, and the battery changes its role to backup and receives charging.

What function does the battery still have?

Even if the engine is stuck, the battery is important because it serves.

- Electric power backup

- Keeps the voltage constant.

- Helps power supply when more power is used than the dicharger produces.

- Reduces the pressure surge to protect the electrical equipment inside the car.

Why do ordinary models and air cabinet models use different sizes of dichargers but use the same size of batteries?

Kubota L5018 Tractor Sample

- Ordinary version. Use 40A dicharger.

- Cabin model (Air Cabinet) using 55A dicharger

- Both models use the same 75D26R battery.

The reason is that air conditioner models have increased electrical equipment such as air fans, compressor clutches, cabin lights, and other equipment, resulting in more current consumption, thus requiring a higher power dicharger.

The battery part is mainly responsible for starting the engine. Both models use the same engine, so they can use the same size of battery.

The function of the three dicharger terminals

B + (Battery)

It is the main power terminal of the dicharger, serves to power the entire electrical system and recharge the battery.

IG (Ignition)

Receive power from the key switch when twisted to the ON position to turn on the regulator operation and trigger the field coil inside the dicharger, making the dicharger ready to produce power as the engine rotates.

WL (Warning Lamp)

It's a battery warning light control terminal on the dial.

- Before starting, the warning light will be on because the circuit is still grounded through the dicharger.

- After starting, when the dicharger produces the light, the pressure on both sides of the lamp is the same, so the warning light goes out.

Summary

The tractor's electrical system does not use battery power alone. Once the engine is attached, the dicharger provides the main power supply to the entire system and recharges the battery along the way. The battery acts as a backup, preserves the voltage, and reinforces the dicharger's overpower.

Once this principle is understood, it makes it easier to analyze problems with batteries, dichargers, charging systems and tractor electrical systems and can be maintained more accurately.

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