All about

Rotating Electrics

All about

Rotating Electrics

Rotating Electrics products

General information

Our unwavering focus on delivering outstanding quality, advanced design, and innovative vehicle parts and technologies to the global car market has led our rotating electric products to set the OE standard across Europe. By working closely with automotive manufacturers such as Toyota, Fiat, and Land Rover, we’ve developed starters and alternators that offer exemplary performance and are the product of choice for a huge range of OE manufacturers.

Subject to rigorous manufacturing and testing processes, our starters and alternators guarantee high levels of performance and fit a large range of car models. As well as meeting DENSO’s strict quality standards, our rotating electric products use completely new parts. This means our starter motors and alternators can be relied on to replace worn-out car parts and facilitate high, reliable performance journey after journey.

Installation and fault finding

To take advantage of our rotating electric products' premium quality and advanced design, you need to install them correctly and fix any faults quickly. Download our guides to find out more about DENSO's starters and alternators.

Catalogues and marketing materials

To find out more about Rotating Electrics browse the Downloads Area section. Click here.


How do car starter motors work? 
Starting a car's engine requires external force. The starter motor is an electric motor that turns over or "cranks" the engine. The starter drives a built-in motor using the vehicle's battery; it receives power from the battery when the ignition is turned on. When the starter motor is energised, an electromagnet engages, pushing out a rod attached to the pinion gear. The starter pinion gear mesh with engine ring gear that a removable part installed on the flywheel.
What parts does a starter motor have?
The starter includes a solenoid - a magnetic switch that activates the starter motor to crank the vehicle's engine. The starter contains an armature - a part that converts electricity to mechanical energy. A drive lever engages the pinion gear with the flywheel ring gear. The pinion gear is a small gear attached to the armature through an overrunning clutch. A yoke and pole core is a component that houses field coils; four field windings are attached to the starter motor housing from the inside. A plunger moves the drive lever. Lastly, brushes run to conduct electricity.
Why do a car's lights dim when the starter is operated?
When the starter is operated, it draws high current from the car battery. This leads to a significant voltage drop across the battery's internal resistance, reducing the potential difference across its terminals. Consequently, the potential difference across the light bulb is reduced, dimming the car lights.