Diagnosing Your Motorcycle’s Charging System 

Understanding the charging system on your motorcycle will help you diagnose any future issues, some that are easy to troubleshoot.  

Motorcycle charging system testing

The charging system on a motorcycle is a pretty universal design across most makes and models, with only slight variations between them. 

Watch the video below to see how to test the charging system on a motorcycle

Check the Motorcycle Battery

The first place to look when diagnosing a charging or starting problem is usually the battery. 

Motorcycle charging system battery testing

Motorcycle’s batteries hold the juice to start up your bike and power on lights when the machine is not running. Whenever you’re experiencing charging or starting problems, this should be the first place you look. Checking the battery’s health and troubleshooting battery problems is pretty straightforward.

Diagnosing Battery Problems: Quick Check

  • Check that all connections are tight and not corroded 
  • Use a digital multimeter or battery tester to check the battery's voltage:
    • Standing voltage for a healthy battery should be around 12.5 - 13 volts
    • Running voltage while charging should be between 13 - 15.5 volts

Your motorcycle's battery will have an inline fuse and/or run straight to a fuse box, then to a starter solenoid relay. 

Watch the video below to learn how to diagnose motorcycle battery problems

Check the Fuses

Fuses are the safety gap between your motorcycle’s battery and other components.  

Motorcycle charging system fuses

If there’s a surge of power, the fuse will break the connection before it travels to the more complicated components, and causes damage to the expensive bits like the bike’s engine control unit. 

Fuses are the easiest thing to check. Simply pull them out to confirm they’re intact. If a fuse is fried, just pop in a new one, making sure you use the correct size fuse. In other words, putting a 10amp fuse in a 30 amp spot will burn out that fuse.

Watch the clip below to learn how to check the fuses on a motorcycle. 

Check the Regulator Rectifier

A regulator-rectifier regulates the voltage coming from the stator to prevent too much power from coming out of it. 

Motorcycle charging system regulator-rectifier

The regulator-rectifier also converts the alternating current coming from the stator to direct current, which the electronics and battery all use.  Any power drained from your battery on startup is then recharged for the next use. Once the battery starts the machine, the stator starts generating power and the bike runs on its power. It’s a consistent regulated amount of power to run the electronics on your bike. 

Due to the heat and amount of power that runs through them, regulator-rectifiers tend to burn out occasionally. You can test a regulator-rectifier by using a multi-meter. 

Watch the video below to learn how to test regulator-rectifiers.

Check the Stator

Stators are a motorcycle’s version of an alternator in a car.

Motorcycle charging system stator

When the engine is running, the stator generates the power to run your motorcycle and charge its battery. It essentially allows the motorcycle to create its own power source. When running, the stator should put out 14-15.5 volts. If it’s generating more or less than that, the stator could be going bad, and if you’re getting more than that at the battery, then the stator and rectifier should be checked.

Watch the clip below to learn how to test a motorcycle’s stator.

Don’t forget to check all of your motorcycle’s connections, and make sure they’re tight and corrosion-free, as many troubleshooting issues can be resolved by simply checking for loose wires or bad connections.

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