Today we're going to review a bike's charging system because...
Have you ever wondered about your motorcycle's charging system and how it works? Have you ever wondered how similar motorcycle charging systems are to cars? No? Well then today's your lucky day!
Firstly, if you're familiar with cars or trucks you'll know that your car has an alternator, sometimes easy to reach (Toyota Mark II)...
Sometimes not (MINI Cooper)
??
However, if you look at your motorcycle...
try as you might you wont find anything resembling this.
So, does your motorcycle even have an alternator at all?
Of course it does, but where is it?
Here
Motorcycles have a different problem compared to cars in that they don't have relatively unlimited space for components and also have a weight limit since the vehicle is entirely dependent on the rider being able to control it with their body. If the bike's mechanicals are too big or too heavy, then the motorcycle wont be as usable and enjoyable.
That means there is a big need to simplify and add lightness.
Firstly, understand how the motorcycle alternator compares to anything, let's look at a traditional car alternator, been in use since the 1960's developed interestingly by the U.S. military.
Automotive alternators consist of two basic parts, the stator (which stays static, or doesn't move), and the rotor (which rotates, or spins). Similar to a little windup flashlight, the rotor spins and creates electricity (grossly oversimplified).
The motorcycle alternator uses the same basic parts, they just look a little different. Notice how it's very flat, this is to save space as you can't have big parts sticking out of the side of your bike.
You might also know that the rotor on motorcycles, is often not called the rotor, but rather the magneto. This is because there are magnets on the rotor, and it is a neat-o device. Jk, but there are magnets on the rotor, and the amount of magnets is directly proportional to the poles (the cooper tower things) on the stator.
So how do motorcycle charging systems differ from cars?
Firstly, motorcycles rotors are actually a 3 in 1 part often times. The rotor is weighted so it acts as the flywheel, but then on the flywheel there is often an hall sensor attached to it which also means the flywheel is also the ignitor (triggers the spark plug), and then of course since it has magnets inside, it acts as the rotor for the alternator as well. It's actually quite ingenious how it's done, as a single part can act all as three, where as a car has a separate flywheel, ignitor and alternator.
Motorcycle
Automobile
Hall sensor and trigger location (crankshaft, sometimes camshaft)
Alternator driven by belt
Flywheel
The reason cars likely have extra parts however is because of the nature of working on cars. On motorcycles the engine is completely exposed often times on both sides, much like how a car's engine would be on an engine stand, where as the car's engine is buried so the only practical way to make repairs is to remove external parts without requiring an engine pull each time your battery goes flat. So it's not the car's fault, just a necessity.
Another way that motorcycles differ from cars is that their 4 wheel counterparts is their independent ignition system.
Did you know that without a battery, you can not bump start your car? Cars use a battery dependent ignition system, meaning that the battery must be present in order to get your car running because unlike a generator, the alternator will not produce electricity when spun. The alternator requires external power to energize it's magnets. This keeps the alternator more fuel efficient because you can effectively control the strength of the charge with a regulator (shut it off completely or turn it on) to save fuel/energy.
A motorcycle however has a permanent magnet rotor, and this enables it to generate electricity without a battery. This is why you can kick start a motorcycle without a battery, but not a pop clutch start a car.
One last way in which motorcycles (cheaper ones) differ from car is the "principle" they charge their systems under. This is a very oversimplify view, and I am well aware of motorcycles that do not use this method.
To understand why, first we must understand how a car charges it's battery and powers it's systems.
The alternator a car uses (remember from before) is effectively powered by it's battery. While the alternator produces electricity from mechanical movement, electricity itself is what controls the alternator. This is done via a voltage regulator, which also converts AC to DC (alternating current, hence the name, alternator).
Now one thing to note, see how the voltage regulator says 14v? This is not a misprint. If you think about it, the way batteries are charged (simply put) is by a voltage difference. You can not charge a 12 volt battery with 12 volts, because the voltage (pressure) is the same, and no "flow" will occur. This requires the voltage regulator to have the alternator produce 14 volts.
So now, the main advantage to this system is that once your battery is maximum capacity, you can disengage the alternator and allow it to spin freely, causing less drag on the engine and increasing fuel economy.
A motorcycle does not function this way, because of it's permanent magnet (that ingenious 3 in 1 part earlier on). Because the magnet is always "on", the alternator is always producing electricity (hence the reason they can start with no battery).
So now you have the tricky problem then of what happens when your battery gets full. Are you going to overcharge it and create lots of explosive hydrogen gas? Actually yes...if you have an old motorcycle. This is why it's very important to top off your battery with distillers water, because the excess energy turns the water into hydrogen and oxygen and bubbles away your electrolyte. See the vent tube?
If you have a new motorcycle however, you have what is called a rectifier which limits the amount of current flowing to your battery. The charging voltage tops out around 14 volts just like a car, but unlike the car since it is unable to switch off it's alternator, it simply converts the excess electricity to heat via an internal resistor, (much like how an incandescent light bulb works and gets hot). That is why you see motorcycle regulators with cooling fins often (see below), and also why they are almost always mounting on the frame or front so that air can pass over them.
So there, I hope this helps you understand how your motorcycle works a little bit better, and also why things are the way they are.
Until next time
-Akira S (AE86)
How motorcycle/scooter charging systems differ from cars
-
- 440 newbie - handle with care
- Reactions: 0
- Posts: 8
- Joined: Mon Feb 15, 2016 10:22 am
How motorcycle/scooter charging systems differ from cars
Last edited by Cambodia Motor Guide on Tue Feb 23, 2016 10:08 am, edited 1 time in total.
All about motoring in the Kingdom of Wonder
Author: Akira S. (username: AE86)
Author: Akira S. (username: AE86)
-
- Least Likely to be a Moderator, ever !
- Reactions: 0
- Posts: 3940
- Joined: Thu Aug 01, 2013 1:29 pm
-
- Similar Topics
- Replies
- Views
- Last post
-
- 3 Replies
- 428 Views
-
Last post by ផោមក្លិនស្អុយ
Wed May 17, 2023 6:37 pm
-
-
S8+ keeps saying "moisture detected in charging port"
by EricaR » Wed Sep 09, 2020 11:58 am » in The IT and Techy Forum - 14 Replies
- 2589 Views
-
Last post by 1984
Thu Sep 10, 2020 6:09 pm
-
-
- 9 Replies
- 870 Views
-
Last post by Spigzy
Thu Dec 01, 2022 10:18 pm
-
-
Electric cars are becoming popular in Cambodia
by Oscar Zhao » Thu Jul 23, 2020 12:57 pm » in Cars and Bikes - 39 Replies
- 12225 Views
-
Last post by ragtag
Wed Oct 27, 2021 7:39 pm
-