Will A Bad Alternator Diode Drain The battery?

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Waking up in the morning to find out your car would not start as a result of a drained battery is an unpleasant experience, especially when in a haste to get to the office on time. could a bad alternator battery be the reason for the drained battery?

So, will a bad alternator diode drain the battery? Yes, it will. A bad alternator diode is a threat to the car battery and works against it.

When an alternator diode becomes bad and begins to malfunction, rather than helping to charge the car battery, it becomes the parasite that drains the charge out of the battery and causes it to run get run down.

Normally, an alternator diode is designed to allow a one-directional flow of current and to disallow current flowing the other way.

However, a bad alternator diode drains the car battery by allowing the charging circuit to stay open when the car engine has been put off.

This causes the car battery to continue to discharge its charge overnight and to become completely emptied of charge by morning. This is a common cause of the car not starting in the morning.

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How does a bad alternator drain battery?

A bad alternator is not a simple car electrical problem that should be ignored or managed, rather, it is the type of electrical problem that demands prompt action on the part of the car owner.

A bad alternator diode no doubt will cause the car battery to get run down especially overnight.

It however does way more than that, hence the need to get it replaced as soon as possible. A bad alternator does not only drain the battery but leads to a sequel of problems that can cost the car owner some considerable amount of repair money.

When the alternator diode becomes bad, the charging circuit attempts charging the battery by AC which can burn out the battery with time. the AC power is equally dangerous to the regulator and can also get burnt. Various other damages could result from a bad diode which is not fun to find out.

Rather than taking the battery for a recharge anytime, it gets run down, figuring out the cause of the drain will be a more affordable solution.

Most commonly, when car owners complain of their car not starting in the morning after parking it in the garage the evening before, the alternator diode or other similar problem may be responsible for the battery drain.

When the car is left to sit in the garage for days, the alternator continues to drain the battery even when the car is not running and can empty all the charge eventually.

Visiting a car repair center where they have an alternator testing station that can verify if the source of the drain is from the alternator will help you decide on the next course of action.

Car owners who over the years of driving have experienced multiple episodes of bad batteries and bad alternator diodes can tell without visiting an alternator testing station, who the culprit is.

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Signs that the car alternator is bad

There are numerous signs in a car that can be interpreted as a bad alternator. Whenever the alternator begins to malfunction, the car’s electrical system presents various signs which can be explained based on the malfunction. 

To rule out the car alternator as the cause of the battery drain, there are certain questions you need to ask yourself regarding the car.

First, does the alternator voltage output get to 14 volts and above? Alternators with insufficient voltage output (less than 13.8 volts) cannot adequately charge the car battery and may lead to a battery drain.

Does the electronic aspects of the car work perfectly? Whenever the alternator begins to malfunction, another electronic aspect of the car becomes affected and also begins to malfunction. One of the easiest places to spot this is with the car headlights. Bad alternators cause a dim headlight brightness even when the engine is on.

How many attempts do you make when trying to start the car? If the car can be started right back after putting it off, the car alternator may not be responsible for the battery drain, you may have to query other power-draining vampires for answers.

Therefore, before taking the car to repair stations with a testing center for the alternative, see how many boxes you can tick from the above signs of a malfunctioning alternator.

One of the common signs that the alternator diode is responsible for the drain is that such drain usually happens overnight when the car is not running.

Sometimes it happens in minutes, that is, one minute the car is running perfectly, the next minute is unable to get started. This means the alternator was draining the car battery all along during the drive.

How to find out if your car alternator is draining your battery?

Sometimes, it is hard to differentiate what the cause of the car problem is between the alternator and the car battery itself.

However, there is a simple trick to this. the question is, does your car engine start when you turn on the car and then back immediately after? If this is the case, then the most probable cause of your problem is the car’s alternator.

However, if the problem is such that the car can be started by jump start and the engine can continue to run for a long time, but cannot be turned on again unless by jump-starting again, you may want to think of a dead battery as the cause of this problem.

Yes, the car battery is continuously working even when the car engine is turned off, the battery continuously serves gadgets in the car such as the clock, radio, and alarm system.

The total of power consumed by this gadget is however not enough to cause a battery drain overnight except if you forgot the interior lights or door lights or other similar lights on over the night.

Other reasons why an alternator may drain the battery?

Whenever you turn on the car engine, the power from the running engine is used to charge the car battery via a charging circuit created by the alternator.

The alternator is a key component of the car’s electrical system as it converts the power from the car engine into electrical energy. This electricity is what keeps charging the car’s battery as long as the engine is running.

Aside from a bad alternator diode, there are other reasons why an alternator that is supposed to charge the car battery becomes the power-sucking vampire that drains the battery. 

For an alternator to charge the car battery, there is an optimum amount of power the alternator must produce, any amount below that will cause the alternator to drain the car battery of its charge.

An alternator whose voltage output is less than 13.8 volts is said to be unable to charge the car battery and may lead to a battery drain. Car owners with such alternators should consider replacing the alternator with one that gives out adequate voltage.

In the instance given above, the alternator is intrinsically unable to provide adequate charge for the car battery, however, a fully functioning alternator that is capable of producing adequate charge may cause battery drain if the wiring connection between the alternator and the car battery is defective.

The defect could be in the form of a fault or dirt in the battery cable interfering with the flow of charge from the alternator to the battery.

It could also be as a result of a break in the cable or the cable not being tight enough thereby giving a partial contact. Either of these scenarios will cause the alternator not to be able to deliver adequate charge to the car battery which will lead to its drainage.

Car owners who constantly experience their car batteries draining out overnight all the time may have to question the efficiency of their car battery charging system.

Do a thorough survey of the charging circuit, while keeping an eye out for worn out or lose alternator belts, broken wires, loose connections, or disconnections.

You should also remember that the alternator or the components of the charging circuit are not the only factors that could cause a drain, engine operation problems could also.

Can an alternator with a bad diode still charge the battery?

the commonest cause of a failing or failed alternator is a bad alternator diode, however, at the stage where only one or two of the alternator diodes are bad, the alternator will still be able to perfume its functions although not optimally. It will be able to charge the car battery and cannot get it fully charged.

Will A Bad Alternator Diode Drain The Battery – Conclusion

While there may be other battery-draining vampires, a bad alternator diode is one of the commonest causes of battery drain especially when the car is parked overnight. It should be replaced as soon as possible to prevent further damage to the car’s electrical system.

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