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.
Will an alternator still charge with a bad diode?
Bad diodes are a common cause of alternator failure. If only one or two diodes have failed, the alternator may still produce enough current to meet the vehicle's electrical needs, but it may not be enough to keep up with higher loads or keep the battery fully charged. This could cause the battery to run down over time.
How do you test a bad diode on an alternator?
- To check for a possible bad alternator diode, switch your voltmeter to a low setting on the AC (alternating current) voltage scale
- With the engine running, touch the meter probes to the battery terminals
- Your voltmeter should read 0 AC volts. Any amount of AC voltage indicates a bad diode - you'll need to replace the alternator.
Is an alternator expensive to replace?
What is the cost to replace an failing alternator? Keep in mind that replacing a failing alternator is expensive and sets you back anywhere between $400 and $850. If you buy original parts directly from a dealer, it is costlier. You can try rebuilding the unit as it hurts your pocket significantly less.
Can I repair my alternator?
Can I fix my alternator? You can either take it to a repair shop or repair it on your own. Is this true? This auto repair requires you to connect the battery, remove the belt, and unbolt the alternator.
What happens when alternator diodes fail?
Leaky or shorted alternator diodes can cause rapid changes in the output voltage of the charging system. In addition, bad diodes can also allow current to leak from the battery back through the alternator to ground.
How do I know if my alternator diode is bad?
Checking for a Bad Diode Usually, a bad alternator diode will cause your headlights or instrument panel lights to flicker or dim and, sometimes, drain battery power overnight, or in minutes.
Can an alternator still charge with a bad diode?
When diodes fail, the charging output of the alternator drops. If only one or two diodes have failed, the alternator may still produce enough current to meet the vehicle's electrical needs, but it may not be enough to keep up with higher loads or keep the battery fully charged.
Can you fix an alternator instead of replacing it?
That said, there are some circumstances where repairing an alternator may make sense. If the belt is showing signs of wear or breaks, an alternator belt (sometimes called a serpentine belt) can be sourced and replaced without having to replace the alternator itself.
Can a bad diode drain a battery?
A corroded or defective alternator diode will faultily continue charging the circuit even when the car off. This, in turn, will drain your car battery and cause the car not to start.
What would cause a diode to fail?
The common reasons for a diode failure are excessive forward current and a large reverse voltage. Usually, large reverse voltage leads to a shorted diode while overcurrent makes it fail open.
What does a diode do 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.
Can an alternator test good and still be bad?
Tools Required. If you have a newer battery but your car won't start, you may have a bad alternator. If you're tempted to test an alternator by disconnecting the negative battery cable, don't do it. A good alternator may indeed keep the engine running without the negative cable, but this was never a good test.
Can a bad alternator drain a new battery?
Contrary to its purpose, an alternator can drain a battery. It's rare, but it's possible. A draw on the battery only occurs if there's a problem with either a component in the alternator itself or connections to it.
What else should be replaced when replacing alternator?
When replacing and alternator, other upgrades are worth doing too. Go ahead and change the serpentine belt, tensioner and idler roller when replacing an alternator on your car or truck.
Can a faulty alternator be repaired?
Alternators are simple machines & can certainly be repaired. You need to ask them exactly what part of that alternator has failed and that part can be replaced. For e.g. the alt may be mechanically sound but the brushes are worn out or the rectifier, regulator may have failed.
Can you refurbish an alternator?
Rebuilding an alternator is a fairly simple procedure, which anyone with basic automotive knowledge can accomplish. Although the construction of some brands will vary slightly, the basic anatomy of an alternator consists of the same components. Follow these steps as you learn how to rebuild an alternator.
What does an alternator diode do?
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.
How do you test a alternator diode rectifier?
11:3914:14How to Test an Alternator ( Testing the Voltage Regulator, Diode rectifier ...YouTubeStart of suggested clipEnd of suggested clipSo turn the dial into diode test mark and connect one lead to the B post. And the other lead ontoMoreSo turn the dial into diode test mark and connect one lead to the B post. And the other lead onto the alternator housing. Then even swap the leads over and see the reading again.
What are the symptoms of a bad voltage regulator?
Bad Voltage Regulator SymptomsToo High Voltage in the Battery.Dead Battery.Battery Light or Check Engine Light.Inconsistent Operation of Electrical Components.Vehicle Dies While Running.Dimming/Pulsing Lights.
How do I know if my alternator is draining my battery?
A battery test is easy to perform and can be done at home. First, open the hood and start the car. While the engine is running, remove the negative cable from the battery. If the vehicle stalls or dies, the alternator is likely bad.
Which brand of alternator diodes has the lowest price?
AutoZone has the lowest prices on alternator diodes and other components such as bearings, bushings, brushes and pulleys. You can choose from a variety of Duralast diodes and other parts sold by top brands such as ACDelco, Dorman and National.
What is a diode?
Diodes are designed to rectify current by rotating. The battery and other electrical systems depend on a rectifier and diodes to generate the current necessary for safe operation. You can find the best alternator diodes for cars and trucks when you shop online or in store at AutoZone. Causes of Diode Failure.
Why do diodes fail?
Shorted diodes can eventually cause issues that make it necessary to rebuild or replace an alternator. Diodes are among the most common alternator components to fail.
Why is my alternator hot?
A heavy charging load may cause diodes to become hot and burn out. The charging output of an alternator may become limited as one or more diodes shorts out. Diode failure can lead to an inability to maintain a battery charge and issues with other alternator components that require repair or replacement.
How are diodes connected?
The diodes are connected with a bolted connector to an isolated stud with a nut.
Can you swap alternator parts into old case?
If have a nice case, or orginal... there is no reason that the 'new alternator components cant be swapped into the old case.
Is a diode tuff?
The diodes are as tuff as horse shoe nails... so dont jump too soon that its a diode.
Installation
Diode battery isolators allow simultaneous charging of two or more batteries from one alternator, without connecting the batteries together.
Sensing Issues with 1-wire Alternators
Some 1-wire “self exciting” alternators rely on a direct connection to the battery to sense and provide charge as they do not have a separate lead that can be connected to sense battery voltage. In this case a standard diode alternator will not work as the diode itself will block access to sense voltage from the batteries.
What is an alternator diode?
The important thing to remember is that the diodes used in an automotive alternators are actually TVS diodes that clamp the voltage to a maximum of 32-40 Volts in the event that the battery goes open circuit while the alternator is at full load. This protects the car from over voltage in the short time (milliseconds) that it takes for the regulator to reduce output of the alternator. Since the rectifier diodes are also TVS diodes, it's a fail safe system. Failed TVS diodes also mean that the rectifier diodes are failed so the alternator can't put out any current.
Why is it so hard to replace diodes?
The main problem is that the diodes are pressed into the diode plate and look sturdier than they actually are , making replacement a complicated issue. The press fit is a bit of a challenge as a bad contact with the carrier plate results in heat-death of the diodes under full load, combined with spurious electronic problems. Also it could be that acquiring matching replacement diodes is difficult.
How many amps does a 3 phase alternator need?
If you chose to bring out the 3 phase AC alternator output you'll need a 3 phase rectifier that can handle around 100 Amps. That's about 200 Watts generated and heat sink needed without considering the high temperature of the engine compartment, so it's actually closer to 400W of heat sink for normal temperatures. You still have to have TVS diodes to protect the output from voltage spikes. Also, keep in mind that the wire connecting the rectifier to the battery may be a fusible link to prevent a melt down and fire if the alternator rectifier shorts out.
What is the rectifier part number on a 99 Nissan Almera?
This is a 99 Nissan Almera 1.6L GA16DE and the rectifier part number is 231240M011.
Can you take any alternator?
I'd rather look for a rectifier unit as a whole, or just a new alternator altogether. If it physically fits right, and the pulley size is about the same, you can take any alternator you want. It looks like a very common one, so it should be easy to find a fitting replacement.
Can you replace a slip ring on a lathe?
Additional problems: The slip ring is most likely consumed, in some cases it is possible to repair it by turning it with a lathe. Also the brushes would need replacement. The bearings should be easy to replace, opt for rubber sealed C3 bearings if you have the possibility.
Can you use 50A diodes?
Possible, sure. But you need some beefy diodes that can handle an amperage of at least 50A, and at the right spec. (think about type, voltage drop, switching time, reverse blocking specs, temperature...) Otherwise you might get some unexpected magic happening in your electronics, or release the magic smoke in them.
