Can A Bad Alternator Destroy A New Battery?

A battery is not a cheap investment, and the price gets even higher with maintenance. All car owners do their best to prevent any damage to their car battery to avoid incurring the extra cost; however, it does not always work out, though it is worth the effort.

The battery may get damaged due to internal or external factors. One of the problematic external factors that can affect your battery is the alternator.

Both the alternator and the battery are essential in a car, and if one gets damaged, it may affect the other.

This piece gives an in-depth explanation of how a bad alternator can destroy a good battery without proper caution.

Does a bad alternator kill a new battery?

Let’s start from the basics of discussing the definition of an alternator. An alternator is a primary component in the car engine.

It functions as a generator by channeling extra electrical energy as the car is running. Moreover, the alternator charges the battery. The device has a pretty long lifespan of about 10-15 years.

An alternator plays a significant role as a charging component to the battery. The good news is that a faulty alternator does not necessarily affect a new battery immediately.

Nevertheless, there are instances when a defective alternator can destroy a new battery.

Ways in which a bad alternator can ruin a new battery

Overcharging the battery

A defective alternator has a chance of overcharging the battery, resulting in a very high voltage that causes the failure of a premature cell.

A faulty alternator eventually leads to the damage of the cell.

Intermittent charging

A bad alternator can cause intermittent charging of the battery. When this occurs, the engine changes the power source to only focus on the battery. The battery in a car engine ensures a steady supply of voltage and current when the driver starts the car. Batteries are not the primary source of power in vehicles.

Ripple voltage

Ripple voltage is harmful to batteries. This effect occurs when the AC passes through the alternator’s rectifier, where the AC converts to DC.

Ripple voltage is detrimental to the battery by damaging it as well as other electronics of the car. Ensure to avoid a situation of ripple voltage as much as possible.

Inadequate charging

A bad alternator will prevent adequate battery charging, resulting in a low battery to keep it working. If this situation persists, it will eventually damage the battery.

How long can a new battery last with a faulty alternator?

Fortunately, your battery can still run as usual despite the faulty state of the alternator. Therefore, you still have a chance to rush back home or to a nearby car service station.

However, the bad news is even though your battery continues to work, it will not last for long. The maximum amount of drive with a bad alternator is 30 minutes.

Therefore, when you realize a faulty alternator, prepare for a desirable route to your preferred destination. Moreover, utilize a familiar path, so you do not have to waste time figuring out your way.

Signs of a bad alternator

Now that you are aware of the troubles of a bad alternator, how do you know your alternator is faulty. Below are signs of bad alternators.


A squealing noise from the engine is the most common indicator of a bad alternator. The noise is a result of the exhaustion of a serpentine belt from the faulty alternator.

Stall Engine

A bad alternator can be the reason why your engine suddenly keeps on stopping.

Service Engine Light

A majority of cars have a service engine light indicating to the owner a fault. The alternator could be the problem that needs servicing.

Causes of a failing alternator

Most car owners are quick to conclude a battery fault every time they experience an electrical issue with their car.

However, if your battery is new and still has problems, you should probably check the alternator.

What causes a faulty alternator?

Dead alternator

A dead alternator is pretty apparent if it has surpassed its lifespan. Wearing out is typical for an old alternator, hence requires replacement.

Sometimes the alternator may wear out before time due to a variety of factors. High temperature is one of the factors that could drain your battery earlier.

Computer issues

Modern vehicles come installed with a computer system like the Electronic Control Unit. The system virtually controls all the car components, including the alternator.

A malfunction of the computer system could stop the functioning of the alternator.

Wiring problems

The alternator receives power from several wires in the vehicle. If one or several cables get damaged or worn out, they could cost the alternator’s job.

Bad fuse

Cars use fuses to maintain the function of the alternator. Fuses blow up in case of a power surge or after some time. A damaged fuse makes the alternator dysfunctional, preventing your battery from charging.

Broken belt or pulley

Alternators produce electrical energy using mechanical power from a pulley or belt. Pulleys and belts are not long-lasting, thus eventually breakdown after a while.

Breakdown of the two or either systems would mean no mechanical energy generated to the alternator for conversion.

Can bad battery damage the alternator?

The relationship between a battery and an alternator goes both ways. The simple answer is yes, a bad battery can damage the alternator.

There are instances when a battery can damage done an alternator.

Battery Short

A battery with an internal short can cause damage to the alternator by making it work harder than usual. The alternator will have to give its highest output consistently for a long time, which shouldn’t be the case.

Open Circuit

An open circuit in a battery will lead to the alternator not charging the battery at all.

Another problem might be the frequent bounce from high to low voltage back and forth, resulting in the premature halt of the regulator’s work.


From this, it is evident that a faulty alternator left alone can cause damage to the battery and vice versa. It is best tokeep your alternator and the battery healthy to avoid damaging the battery and extends to the entire car.

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