The Alternator Charging System - All alternators, rather its a stator under the flywheel on a small engine or belt-driven automotive-type, produce AC (alternating current) electricity. They require an electronic rectifier/regulator to convert the AC to DC (direct current) and to regulate the amount of charge into the battery and limit the amount of voltage throughout the entire electrical system while powering electrical accessories at the same time. The faster the engine runs, the more voltage and amperage the stator produces. Although very reliable, weather-proof and virtually maintenance-free, this system produces an adequate charge at low idle speeds. This system is the standard of todays charging systems used on virtually all small engines, motorcycles, snowmobiles, automotive engines, heavy equipment machinery, etc. And unlike the belt-driven automotive-type alternator, an alternator under the flywheel is self-energizing. It will produce electricity when the flywheel is spun fast enough. How to Identify the Three Wires Coming from an Engine - Use a digital or analog multimeter set on the Ohms resistance to test each wire coming from the engine. With the engine not running, ground one test lead to the engine, and connect the other lead to each wire one at a time. If one wire shows resistance, this is the ignition kill wire. If the engine has points, the crankshaft may need to be rotated by hand until the wire shows resistance. (This is when the points close.) And if the other two wires show no resistance, these are the stator (charging) wires. When the test leads are connected to the two wires with no resistance, they should show 100% resistance. These two wires connect to the voltage regulator/rectifier. Be sure to mark each wire with masking tape or something to identify them. How to Test a Stator - First of all, all stators produce AC voltage and theres a diode built-into the voltage rectifier/regulator. (Rectifier = converts AC to DC; Regulator = regulates voltage to the battery and other electrical accessories.) If the diode is shorted, itll drain the battery and burn up the stator windings. The stator windings are not originally grounded, theyre isolated from the engine block. And dirt on the stator or the magnets in the flywheel dont inference with the magnetism to the stator whatsoever. Stators rarely go bad, unless the two wires are connected to each other while the engine is running, causing a short. To test if a stator is good or not, use a digital multimeter or analog multimeter set on Ohms resistance. With the engine not running and the wires to the stator disconnected from the voltage rectifier/regulator, connect the test leads to the wires on the stator. If the ohm meter shows resistance, the stator is good. Then connect one test lead to each stator wire and the other test lead to the metal frame of the stator. There should be no resistance. With the engine running, when testing the voltage output of a 15amp or higher amperage stator, connect the two wires coming from the stator to a digital multimeter or analog multimeter set at more than 28 volts in the AC setting. With the engine running at full governored speed, the reading should be 28 to 36 volts. If its less than 28 volts, the stator is bad. If the reading is more than 36 volts, the windings may be burnt, causing a short within the windings, resulting in an increase of voltage, which will likely cause the voltage rectifier/regulator to go bad, and possibly burn up the battery, ignition coil and/or electrical accessories. This testing procedure applies to all makes and models of small engines, including motorcycles and snowmobiles with the stator under the flywheel. Make sure the slip-on terminals on the stators wires are in good condition and fit snug on the voltage rectifier/regulators spade terminals. If the slip-on terminal(s) fit loose or have a faulty connection due to rust, they could arc while charging and burn out the spade terminal(s) and/or the heat from the arcing could travel inside the voltage rectifier/regulator and burn it out.
Posted on: Sat, 15 Nov 2014 07:40:39 +0000
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