My 1110d won't charge. With the engine running I unplugged the alternator (generator?) and used a multimeter to test for voltage and it read zero.
I removed the alternator (generator?) and see that it is a permanent magnet type.
I've done a little research and I'm confused about if it is an alternator, generator, dynamo, and how to test it and the voltage regulator.
If anyone could give me some advice on how to proceed I'd appreciate it.
Thanks,
Bruce
I can help you with it if you would prefer to learn about them or do it yourself. Certainly there isn't anything wrong with just taking it to an automotive electrical shop. But sometimes it is fun to know a bit more. And you did ask some good questions.
BTW, the most common problem with an alternator, AC generator, or magneto (all sort of the same thing) is not the magnets or the coils inside, it is usually that the diodes on the diode plate on the back of the AC generator have failed. You might try your multimeter on the AC setting and see if spinning the alternator on the tractor gives you about 20 volts AC instead of any DC voltage. If so, it's one or more diodes that need replacement. They just solder in.
I'll answer some of your questions for the future
Is it an alternator or a generator or a dynamo? Well, it's any and all of those. They all do the same thing. Anything that generates electricity by moving a magnet a past a coil is a generator of some kind. And more specifically, it is an AC generator. No matter how, all generators make AC voltage by moving a magnet by a coil, and each one has a different way to convert that AC voltage into a DC voltage that is more easily regulated and can be used to charge a lead/acid battery. The different names actually refer to how each one converts the AC voltage into a DC voltage.
The traditional automotive GENERATOR from about 1920 up till the mid 1960's used carbon brushes running on a divided plate called a "commutator" to mechanically convert the AC it made into a DC that could be regulated and used for batterys and lights. Magnets at the time were weak, so instead of magnets, the GENERATORS used large "field coils" to make a magnetic field that their other coils moved past. GENERATORS were big and heavy and complicated....but remarkably reliable.
Later on, in the mid 1960s, two things happened: Semiconducting diodes were invented and could be used to convert AC into DC. These diodes did away with the need for brushes and commutators.
At about the same time, the first of the modern high powered synthetic magnets "ALNICO" was invented. ALNICO magnets did away with the need for field coils.
As a result, the ALTERNATOR was born.
Note that you still have to have a motor to move the coils & magnets past one another, and there are some times when the motor is built right into the GENERATOR or ALTERNATOR. When that happens, the combination is called a DYNAMO.
Household backup generators and portable welding generators are examples of DYNAMOs in use today. Just to confuse things, they are both called generators instead of their proper name which is a dynamo. And to confuse things farther, they are more closely related to motors plus alternators than they are to the ancient motors plus generators of the early 1900s....But if you put a motor and a generator together you have a DYNAMO.
The whole basis of all of this is the simple fact that anytime you move a magnet past a coil or a coil past a magnet you generate a voltage in the coil. The voltage goes up - call it positive - as the coil approaches the magnet and the voltage goes in the other direction - negative or down - as the coil moves past the magnet and away. Voltages that goes up and down between positive and negative that way are called alternating currents. The voltage goes up the faster the magnet and coil move past each other.
Yes, you can move the magnet past the coil if you had rather. And in your Yanmar's AC generator that is how it is done. Usually its a set of six magnets and six coils. Six of each (the number doesn't matter) just to smooth things out. And by moving the magnets and letting the coils stay stationary, you don't have a problem with how to keep the output wires from winding up. If the coils are stationary and the magnets are moving, the wires from those coils are also stationary and that turns out to be a big advantage. If you end up designing it the other way around so that the coils move and the magnets are stationary then you have to interrupt the leads from the coils by connecting them to brushes contacting a rotating ring.... ugh. Better to just move the magnets.
There is probably no need to take your Yanmar alternator apart. All you would see inside is a group of coils all bolted to the backing plate and connected in series, and some magnets cast into the rotor so cleverly you probably cannot even see them. Neither one is likely to go wrong. If you can get to the leads coming from the coils and measure the output there without them being connected to the diodes then you will probably see about 20 volts AC.
If you measure it after the diodes are involved it will be about 12 to 15 volts DC depending on RPM.
You can test the diodes with your multimeter using the ohm (continuity) setting, but you have to disconnect them from the circuit to do so. One side of the diode is screwed to the backing plate, and the other has a wire soldered to it. Unsolder the wire - carefully & quickly because diodes are a little bit sensitive to heat - and the diode should show continuity measured between the free end of the diode and the base plate with the test leads in one polarity. And it should show no continuity with the test leads reversed. Anything else means replace that diode.
If the AC generator (alternator) doesn't show DC output when it is spun, chances are good that bad diodes are the problem. Especially so if it does show AC output....
If the multimeter does show output from the alternator, then the problem is in either the voltage regultor. the ignition switch, or the battery itself. We can go as deep into those as you would like, but this is a good place to quit for now and see if anyone has a question.
enjoy,
rScotty
