Motorcycle 12 Volt Electrical System Basics - Part 1 of 3
Not every motorcycle problem is mechanical in nature. That said, many riders are more familiar or comfortable in their knowledge about engines and other mechanical systems.
And as we know though, a motorcycle isn't just made up of just mechanical parts. The electrical system is just as important and when it starts causing trouble, it can be challenging for even seasoned mechanics to find and troubleshoot the problem. Don’t let that intimidate you though. Patience and a little bit of sleuthing are keys to sorting out electrical issues.
Additionally, modifications or additions of accessories that involves the electrical side of things can be tricky as well. A good chunk of this uncertainty can be chalked up to a lack of awareness of the fundamentals. So, that is what we are going to look at today. Keep in mind that electrical systems, especially those on newer motorcycles, are unique to each make and model. However, the basics are nearly universal and being aware of the fundamentals makes you a better all-around rider.
How do motorcycle electrical systems work?
The basic structure of the electrical system on a motorcycle or any other vehicle for that matter is really just a scaled down version of the power grid used to supply electricity to towns and cities. At the heart of this system is a device to store electrical energy. The power plant generating the electricity is your engine. Your crankshaft turns a flywheel inside a stator that turns mechanical power to electricity. The current then goes through a rectifier to convert it from AC to DC and a voltage regulator to keep the current at the right level when it is sent to your battery.
All the various electrical devices on your motorcycle are then connected to the battery using wires, switches and relays. The package is completed by other devices that are meant to keep the whole system working safely.
Main components of a motorcycle electrical system
There may be dozens of different individual components, but the main systems can be classified into the following five.
The electrical system is a self-contained unit and electricity is needed to start the motorcycle. So, there has to be a place to store the electricity and that is done by the battery. Space is always at a premium in motorcycles which is why your bike’s battery is smaller than you car’s. The two important things that you should be aware of with regards to the battery is its voltage and its capacity. The voltage is almost always 12 volts, but the capacity can vary. It is measured in Ampere-Hours or Ah. The higher this value, the more electrical energy the battery can store. Most 12 volt motorcycle batteries are rated around 14Ah.
Batteries can be further divided into two types. The first is the maintenance-free kind which is most common and found in newer motorcycles. The other type, which can be found on older models requires regular top-ups with distilled water which is usually done when the motorcycle is serviced. The good news is that these older model batteries can be replaced by the newer ones without requiring any modifications.
The battery alone cannot power the motorcycle's electrical system for more than a few minutes. That is where the charging system comes in. You may hear people refer to motorcycles having alternators, but bikes don’t have a set up quite the same as a car alternator. The system is broken into separate components (car alternators have all these components in one unit).
First there is the internal stator that gets power via the flywheel from the crankshaft of the engine. The stator connects to an external rectifier/voltage regulator that converts AC to DC current, manages the load and sends it to the battery. For the sake of simplicity many refer to the whole system as the alternator. But you’ll here stator used frequently as well. We’ll refer to it as the charging system.
As soon as the engine starts, the system begins generating electricity. This is used to simultaneously keep the battery charged up while also providing power to the various electrical devices on the motorcycle while the engine is running.
Just like the battery, the charging system also has a certain output specification. It can only supply a finite amount of electricity. This is important to know when you want to add another electrical accessory to your bike. Most systems are going to put out somewhere in the range of 22- 32 amps
Here's a quick, informative article on motorcycle charging systems. https://www.uti.edu/blog/motorcycle/alternator-vs-stator
The wiring harness is the nervous system of the motorcycle. The various parts that need electricity are scattered throughout the bike. All these are connected to the battery and alternator through a system of wires, connectors, and, relays. They have to stand up to a lot of wear and tear. They are constantly subjected to heat, vibrations, and general wear and tear that comes with time.
As many of us know, this is also where many electrical faults occur. There are yards of wires going all around your motorcycle, and finding the single wire that is causing the trouble can be a challenge. There are some clever ways to troubleshoot issues with the wiring harness which we will look at a little later.
Monitoring & Safety Devices
The electrical system on a motorcycle isn't as well protected as it would be in a car. That is why these monitoring and safety devices play an even bigger role.
Most modern motorcycles have systems that can tell you when something is wrong. This can include warning systems for a malfunctioning battery, an underperforming charging system, as well as overvoltage and short-circuit indicators.
The primary safety devices in your bike’s electrical system are fuses or circuit breakers. These can be inline fuses for various auxiliary devices or part of your bike’s primary fuse block or secondary fuse block.
A breaker performs the same function as a fuse, except it can be reset if it trips. Once a fuse blows, it will have to be replaced. Fuses and breakers will protect your devices that need electricity from being damaged when there is an issue with the electrical system. A blown fuse or tripped breaker results in power being cut off from the circuit they are protecting. If that happens, you should investigate the circuit in question to determine if there is a fault.
Auxiliary Electrical Devices
Every bike is different and what you have is very much dependent on your bike model and any additional accessories you may have added. Your standard items generally includes the horn, the starter motor, the lights and your instrument cluster.
Other parts are present depending on your modifications. You may have added other components like additional lights, heated grips or gear, sound systems, mobile chargers, etc. Adding extra devices should be done with careful planning. We will discuss that in the future blog posts.
Trouble shooting often needs to take each of the systems into account. By understanding how the systems work together and understanding the possible causes of various symptoms, you’ll be further along to resolving any electrical issues. In our next blog we’ll go into some basic trouble shooting techniques.
Stay tuned, thanks for reading and get out and ride!
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