How to test whether the excavator alternator is charging？

The battery is charged by the alternator. If you have dashboard gauges, observe whether the battery charging indicator light functions normally. The simplest method is to measure battery voltage after running the machine for a period of time; a drained battery proves the alternator fails to generate power.

As the rotor rotates, excitation current is transmitted to the rotor field windings via contact between carbon brushes and slip rings. If slip rings get dirty, excitation current cannot reach the rotor field windings, which will cause the alternator to stop charging.

Insufficient lubrication or degraded lubricant will raise rolling resistance of the bearing, making the inner and outer races rotate together and triggering excessive wear between the bearing and bearing housing. Severe bearing wear leads to rotor‑stator friction, alternator overheating, and unstable output voltage and current.

Rotor‑stator contact/friction generates excess heat, resulting in unstable current and voltage. In severe cases, the alternator or the electronic components on the excavator will be damaged. Such contact or friction is usually caused by worn or deformed alternator bearings, end shields or housing.