How fast can a bad alternator drain a battery

Q: Can bad alternator drain battery overnight?

Since the alternator isnt generating vehicle electricity, the problem component pulls from the battery, slowly draining it overnight until your vehicle wont start.

Q: Can a bad alternator drain a battery while the car is off?

But when the engine is off, the alternator cant recharge the battery, allowing little electrical mishaps to drain your battery entirely. The battery strain caused by these electrical whoopsies is known as a parasitic draw.

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Insufficient Alternator Voltage
Wiring Problem
How long does it take a bad alternator to drain a battery?
Can bad alternator drain battery overnight?
How do I know if my alternator is draining my battery?
Can a bad alternator drain a battery while the car is off?

battery charger image by Albert Lozano from Fotolia.com

An automotive alternator is a device that converts power from the engine into electricity, which is used to charge the car's battery. In some cases, however, the alternator can actually drain the battery, causing significant problems.

Insufficient Alternator Voltage

An alternator that's not providing enough power can allow a battery to run down. According to Prestolite electric, an alternator producing less than 13.8 volts of power at idle is not producing enough current to charge the battery fully and needs to be replaced.

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. This often happens overnight.

Wiring Problem

Even when the alternator is functional, if the wiring between it and the battery is damaged, it won't keep the battery charged. A broken ground wire on the back of the alternator, a loose battery cable, or a faulty or dirty cable could prevent the alternator from providing an adequate charge.

References

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How long does it take a bad alternator to drain a battery?

How Long Does It Take A Bad Alternator To Drain A Battery? A bad alternator can cause a battery to drain in as little as 30 minutes. However, there are some instances where it might take up to two hours for the battery to drain completely.

Can bad alternator drain battery overnight?

Since the alternator isn't generating vehicle electricity, the problem component pulls from the battery, slowly draining it overnight until your vehicle won't start.

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.

Can a bad alternator drain a battery while the car is off?

But when the engine is off, the alternator can't recharge the battery, allowing little electrical mishaps to drain your battery entirely. The battery strain caused by these electrical whoopsies is known as a parasitic draw.