Diyvehiclerepair
In an automotive electrical system, diodes can be found in several places, including the alternator. Alternator diodes perform three critical functions for the automotive charging system.
- Are diodes part of the alternator?
- Can you replace a bad diode in an alternator?
- Can bad diode cause alternator noise?
- What is the purpose of diodes in an alternator?
- What causes alternator diodes to fail?
- What happens when a diode goes bad?
- Can a bad diode drain a battery?
- Where are diodes in an alternator?
- Can a bad alternator drain a battery while the car is off?
- What is a diode in a car battery?
- What keeps killing my alternator?
- Can an alternator go bad from sitting?
- Why does my car keep burning out alternators?
Are diodes part of the alternator?
Bad diodes are a common cause of alternator failure. The diodes are part of the rectifier assembly that converts the alternator's AC output to DC. The alternator's charging output flows through six diodes in the rectifier assembly before it goes to the battery and electrical system.
Can you replace a bad diode in an alternator?
It is possible to replace all the parts of the alternator, including the diodes in the rectifier plate. The only sure dead of an alternator is a breakage of the case. Even a defect in one of the windings is curable, although it requires expensive rewinding.
Can bad diode cause alternator noise?
A--If the whining sound you describe has a high pitch, it might be a bad alternator diode. The alternator (General Motors still calls it a generator for some odd reason) generates alternating current (AC), but your car operates on direct current (DC). ... A failed diode often whines accompanied by reduced charging output.
What is the purpose of diodes in an alternator?
What Do Diodes Do in an Alternator? Diodes are used within the process of rectification, or changing an AC flow into DC. This is possible because diodes only allow current to flow in one direction. AC, or alternating current, includes current flowing both forward and backward, creating a full sine wave.
What causes alternator diodes to fail?
Because of the substantial load handled by the alternator, the rectifier diodes fail because of overheating, overloading or because of poor connection between the alternator output and the battery positive terminal. Leaky or shorted alternator diodes can cause rapid changes in the output voltage of the charging system.
What happens when a diode goes bad?
A bad (opened) diode does not allow current to flow in either direction. A multimeter will display OL in both directions when the diode is opened. A shorted diode has the same voltage drop reading (approximately 0.4 V) in both directions.
Can a bad diode drain a battery?
Bad Diode. A malfunctioning diode in the alternator can create a parasitic drain on a car's battery. Diodes should allow current to pass in only one direction, but a bad diode will keep the charging circuit open even when the engine in not running, allowing the battery to go dead.
Where are diodes in an alternator?
Your car's alternator (used to be called a generator) will typically have up to six diodes. These are located on the alternators rectifier assembly. Electricity flows through the diodes, which convert the alternator's AC output to DC (which is what the battery runs on).
Can a bad alternator drain a battery while the car is off?
Even while your car is off, your battery provides power to things like the clock, the radio, and the alarm system. ... But when the engine is off, the alternator can't recharge the battery, allowing little electrical mishaps to drain your battery entirely.
What is a diode in a car battery?
Next to the alternator and battery you'll find an essential, though often overlooked component; the diode. Diodes allow current to flow in only one direction. ... Functioning as a gatekeeper for back feed into the circuit, the diode protects essential elements of the car from current spikes.
What keeps killing my alternator?
Alternators put out alternating current, and the battery needs direct current to charge, so there is a voltage rectifier that converts it, and it can suddenly go bad, too. ... Dust and dirt can get into the alternator, and over time cause shorts or wear on the brushes.
Can an alternator go bad from sitting?
An alternator has brushes because it has a slip ring (like a commutator) The slip ring can corrode and the brushes can stick - both are possible causes of failure after a year standing.
Why does my car keep burning out alternators?
Mechanically a pulley could be off-center and strain the alternator bearings. Or in older cars the tensioner may be adjusted too tightly. If it's an electrical death, it could be using alternators from a poor source, like some of the marginal alternator recyclers. They just slap in a new set of brushes and ship it.
