The charging system (my novela):
I'll try to explain how the charging system works.
*** Just skip to the end if you just want troubleshooting help ***
There are three main steps in the charging system.
1) Generation of Power
2) Conversion of Power
3) Regulation of Power
Step 1) Generation of Power
Power is generated by the use of a rotor and a stator. A rotor is simply a metal "disc" with magnets on it which is turned by the engine. A stator is an electrical device (a form of transformer) which converts a change in magnetic field to a change in electrical field. Power is generated when the rotor and its magnets rotate around the stator. The stator converts this changing magnetic field to a changing voltage output. This voltage output comes through three yellow wires to your rectifier/regulator. (The stator and rotor are located behind the right side engine cover in front of the clutch). The voltage output of the stator is in AC form and should be 70Volts or better.
Step 2) Conversion of Power
Remember, voltage from the stator/rotor combo comes through 3 yellow wires in AC form. Your battery and vehicle's electric system does not like AC voltage. It is a DC system. The conversion from AC to DC voltage is known as rectification. Thus the "rectifier" portion of regulator/rectifier. I could explain how a diode bridge is used to convert this AC voltage to DC, but that is rather unimportant.
Step 3) Regulation of Power
In some bikes, steps 2 & 3 are separate, but on our bike (and many others), steps 2 & 3 are completed by the same device (the regulator/rectifier). Regulation of power is required to prevent overcharging the battery. On a car's alternator, regulation of power is done by controlling the magnetic field on the rotor. On our bikes however, the magnetic field is fixed on the rotor (there are actual magnets that are physically fixed on the rotor of the bike). Since the bike cannot control the magnetic field of the rotor, the stator will output its maximum power at any given RPM. If the battery does not need maximum power and the rest of the electrical system does not use it up, the regulator has to do something with the power so it can maintain a happy 13.5-14.5V for the battery. To get rid of this extra power, the regulator shunts it to ground (essentially, it converts the power to heat..which is why the regulator gets soo hot).
*** here comes a long annoying analogy ***
Let me give you an analogy to help clarify this a bit. Lets say we have a water hose hooked to a fire hydrant. There is a building on fire, but the fire is small and on the first floor. To top it off, there are people inside. Now we don't want to run the fire hose full blast through the windows of the building or we may knock those people on their butts. The best method to keep from hurting people while still flowing enough water to put the fire out would be to open the valve on the hose to just the right amount to regulate the flow of water (this is what a car's alternator does by varying the magnetic field of the rotor).
Now our bikes aren't like this....instead our bikes are more like having no nozzle on the end of the water hose with the water turned on full blast. To prevent hurting people, we have to do something else (since we can't control the valve). Well, what our bike does is build a wall which blocks some of the water and sends it down the city drain while allowing the right amount to go to the building. If more water is needed to put out the fire, no problem, we just lower the wall a bit. The real problem comes when we need less water. When we need less water, we block more with our wall and send it down the drain.... however, eventually this drain is going to fill up with water and back up on the streets... this is bad.
The same thing can happen to your voltage regulator... it can only divert so much energy (power) before it starts to "flood". The "flooding" in this case would manifest itself as overheating of the regulator. Eventually, the water is going to find its way over the wall and pour out despite our best efforts... this is the same as our regulator giving up the ghost... the regulator will fail to regulate and will begin delivering more power (seen as higher voltage) to the battery.
How to test the charging system...
If you understood how it works, it's not hard to troubleshoot. It's easiest to start with the battery and work backwards.
Begin by measuring the battery voltage using the DC setting on the voltmeter while the engine is off. A properly charged batteryshould read in the neighborhood of 12.5 Volts or better. Reading 12.5V does not guarantee a good battery, but it is a good first check.
Make a note of that initial battery reading and start up the bike. While revving the bike up to 3k or higher, the voltage across the battery should rise to 13.0V or more. A voltage reading that stays within the 13.0 to 14.8V range across all rpms with varying loads (brights on/off, turn signals on/off, etc) tells you the charging system is working properly. However, it should not exceed 15V at any point. If the voltage does exceed 15V, then you regulator is not doing its job properly and should be replaced.
What if the voltage does not go up to 13V or hangs around thelow 13's and I never see a voltage around 14.1V?
In this case, it could be and overly active regulator, too much load onthe system (turn off your electric vests, driving lights, fog lights, etc) or a weak charging system. To check this, turn off the bike. Unplug the regulator/rectifier from both connectors (the yellow wires & the black/red wires). Start the bike and let idle. VERY CAREFULLY, using a voltmeter set to read AC voltage, measure the voltage between each of the yellow wires. (there are 3 combinations). When revving the engine to 3-4k , the voltage should read 70Volts AC or more. If the reading is lower than this, it is likely the stator is bad or the magnets are worn/missing from the rotor. Do not run the bike for very long while the regulator/rectifier is disconnected as this is very hard on the stator. Did I mention BE CAREFUL? Voltages over 40V are high enough to cause electrocution.
If the AC voltage reading is 70V or better, the regulator/rectifier is likely damaged and should be replaced.... ** Be sure to check all wiring for signs of damage (melting, burnt spots, loose connections, cuts, etc.) as these can cause your voltage output to be low on the DC side.
If your stator readings (yellow wires) came out at a low voltage, you can do a quick check on the windings using a resistance checker (ohm-setting on a multimeter). Check the resistance reading between each of the yellow wires (all three combinations). If any reading differs dramatically from the others, the windings are likely bad (need a new stator). Also check the resistance between each yellow wire and a ground point on the bike. Any reading less than several MegaOhms indicates a short to ground (a faulty winding) indicating the need for a new stator. If all the readings check out, the magnets in the rotor may be weak or missing.
Whew.. I'm tired now...
Topic: Engine rattle & charging system (Read 3306 times)