Motorcycle Electrical’s Explained: Know The Watts And The Volts On Your Bike

Maintenance | 18 Jun 2020

Motorcycle Electrical’s Explained: Know The Watts And The Volts On Your Bike

Many of us often find ourselves at sea when it comes to the knowing how the electrical systems on our two-wheeler functions. While some of us are pretty good at decoding those wattages and voltages, many find themselves fumbling if they have to upgrade their bike’s headlight or add an accessory, which may consume some extra power. Here in this informative piece, we will acquaint you with the basics of a modern two-wheeler’s electrical system. Take this article as a quick beginner’s guide to learn the basics of a standard electrical system on a bike. We are sure it will help you a great deal. Let us start off with some basic terms.


In simple terms, Voltage is the pressure from an electrical circuit’s power source. This pressure pushes the charged electrons (termed as current) through the circuit, and makes it perform any specific work, like running a fan, or illuminating a bulb. This electric pressure is measured in volts (V).

The Voltage of a battery goes down when the battery is used and loses its charge. Similarly, when an electrical application draws power from the battery, the voltage goes down.


Wattage is a unit of power, or in simple terms, of the rate at which energy is consumed. One watt is one joule (a unit of energy) consumed per second (1 W = 1 J/s). So for example, if a light bulb, rated 100W runs for 10 hours, it would have consumed 100W x 10 hours = 1000 Watt-hours = 1 kW-hour of energy. Fun Fact: KW-hour is the unit used for power consumption in our houses as well.


A battery’s Amp Hour rating describes how long it will last while discharging at a fixed rate. For example, a 12 Amp-Hour battery can discharge 1.2-ampere current for 10 hours. If you double the current discharge to 2.4 ampere, the battery will discharge in half the time, or 5 hours, and so on. Can you imagine?

The components of a two-wheeler’s electrical system

A two-wheeler gets its electricity from two sources – a battery and an alternator. The battery stores charge, maintains a specified voltage and keeps the electrical system working when the engine is switched off and no fresh electricity is being generated.

The alternator, on the other hand, generates electricity when the engine is switched on. It takes care of providing electricity to various electrical devices and also charges the battery on the go. Let us take a more detailed look at the various components of your two-wheeler’s electrical system:


A typical 12-volt motorcycle battery is a six-cell unit and is made of a plastic enclosure with each cell having a set of positive and negative plates immersed in an electrolyte. Each cell has a voltage of around 2.1 volts when fully charged, leading to a combined battery voltage of about 12.6 volts. The battery delivers Direct Current (DC) to the motorcycle’s electronics when the engine is turned off. Battery also provides the current to crank up the engine when you push that electric start button on the switchgear.


The Alternator generates electricity once the engine is started. In simple terms, it utilizes the engine’s crankshaft to turn the magnets and produce electricity as an electromagnet. The alternator, however, produces alternating current (AC) which needs to be converted to direct current. This is achieved through a rectifier / regulator which not only converts AC to DC but also regulates the amount of current that is sent to all the electronics present on a motorcycle.

Wiring Harness

The current produced on a motorcycle is channeled to the electronic components through a wiring harness. The wiring harness is a set of wires, terminals and connectors, designed specifically for a two-wheeler model to supply electric power. It plays a pivotal role in connecting various electrical and electronic components on a two-wheeler.

Adding an electrical component to your two-wheeler

Now that you know the basics, let’s talk about a scenario where you wish to upgrade, or add an electricity consuming component on your two-wheeler. You need to ensure that your electrical system is competent enough to do it successfully. This may mean upgrading some or all of your electric components, and the upgrades will differ on a case to case basis.

Here’s what you need to keep in mind.

  1. Understanding the specifications:You need to read and understand the specs of the new electrical system first. For example, a new light system on your motorcycle will have a specific wattage and voltage. Here’s what it would mean:
    1. Wattage – A higher wattage rating for any specific type of lighting system would generally mean more power consumed and more light emitted
    2. Voltage – Higher the voltage of the system, the bigger the size of the battery required. You should always have a thorough look at your two-wheeler’s manual to understand how much voltage can be supported.
  2. You need to ascertain how much load you can put on your electrical system without overburdening it. A good way to figure this out is through the manual. So if your two-wheeler dishes out 400 watts, figure out how much of it is consumed without adding anything extra. You will have to add up the consumption of the stock headlight, taillight, and every other stock electric component. Again, consult the manual for a definitive number on this.
  3. It’s important to note here that the power output of 400 watts mentioned above is at a certain engine speed. When the bike is idling or doing lazy speeds, the output is generally lesser. Always factor that in.
  4. Once you have determined the total power consumption of the two-wheeler, you can subtract that number from our reference 400W number and see if the remaining output would be sufficient to power your new accessory. It is always good to keep a generous buffer here.
  5. The easiest way to connect a new accessory with your electrical system is to power it directly from the battery, wherein its negative terminal connects to the negative and positive to positive. However, the accessory would now draw battery directly from the battery, which means if you forget to shut the accessory off manually when the engine is turned off, it would drain your battery. This problem can be solved with a power distribution block, which blocks consumption if the ignition is not on.
  6. Another important aspect of an electric system is the fuse, which is meant to blow up to save the electrical system from a potential disaster when the current load increases to a dangerous level. So do not replace a fuse with one rated higher, as that would defeat the very purpose of its existence. Also ensure that there is a fuse in place for every new accessory, preferably closer to the power source.
  7. Most decent electrical accessories would come with a manual, with all the details required before installation. Ensure that you follow the specifications and instructions in the manual before installation.

We hope this quick beginner’s guide on electrical systems for bikes was useful to you. Do let us know your thoughts and comments about the topics. Don’t forget sharing this one with your biker friends who you think might benefit from it.

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Comments (2)


19 Mar 2024

Gg lil bro

Mary Alves

25 May 2024

Gostaria de saber se elas %C3%A9 totalmente el%C3%A9trica