Belt Driven Electricity: Challenger Alternators

An alternator is an electricity generator that is under the hood of your Challenger and driven by the serpentine belt. Inside the exterior cover are two coils of wire. One is wound around iron bars that line the outer circumference of the case. The other is wound around a central iron core mounted to the center of a shaft.

The alternator is connected to both sides of the electrical system. As battery voltage is applied to the inner core coil, the belt drives the shaft of the inner core coil, causing it to rotate inside the outer coil. As the core becomes electrified and spins, it becomes an electromagnet. While this electromagnet spins inside the stationary outer coil, electricity is produced.

Electricity production only occurs if the battery is in a low state of charge. The voltage regulator, also located inside the alternator, controls this. The voltage regulator measures the battery’s voltage and supplies battery current to the inner core coil as required to produce the proper amount of electricity required in order to maintain the proper voltage in the battery.

Before passing out of the alternator, the current that’s produced has one more stop. The electricity produced is alternating current. As you may know, your Challenger uses direct current. A bridge rectifier located inside the alternator uses several capacitors to only allow current to flow in one direction. These capacitors act as a one-way valve, only permitting the positive current to pass.

Alternator manufacturers rate alternators based on the amount of current they are capable of, expressed in amperes, or amps. The rating everyone typically refers to is the maximum output rating. This figure is the output of the alternator while it is being rotated at 6,000 rpm. While that is important, it should be noted that the alternator would not operate in these conditions very often.

It’s important to observe the rating printed on the alternator. This rating will give you more real-world information. It is displayed in the following format: 50/120 13.5V. The 50 represents the output of the alternator at idle speed.

The 120, again, represents the maximum output at 6,000 rpm. The 13.5 is the amount of battery voltage applied to the alternator. This is important, as it reflects a more accurate portrayal of the amount of current the alternator will produce under actual, normal use.

It is also worth mentioning that regardless of what an alternator is rated at, it will only produce the amount of current necessary to keep every device running and the battery adequately charged. The voltage regulator inside the alternator regulates the voltage of the system. If there are not added devices on the vehicle requiring more current, the alternator will not use the extra charging capacity.

When you begin to upgrade your Challenger with add-ons, like a larger sound system, auxiliary lighting, additional gauges, larger ignition system, larger fuel system, etc., the stock alternator will not be able to keep up with the additional demand. Replacing your 2008-present Challenger’s alternator with one rated at a higher capacity will:

• Ensure that when all of those devices demand current the alternator will be able to supply enough
• Produce enough to keep the battery properly charged and supply all of the standard equipment.

There are several signs that may indicate that the alternator is failing:

Flickering or Dim Headlights: If the vehicle still starts and runs, be sure to pay attention to your headlights. If they are dim or change brightness as vehicle speed goes up and down, a failing alternator is most likely the cause.

Weak or Dead Battery: If the battery is dead, or seems weak, this can also be an alternator problem. To differentiate between a dead battery or a failed alternator, shut the engine off. Then turn the key back to the on position without starting the engine. Observe the voltmeter on the dashboard. If the voltage is reading normal, it’s probably the alternator. If the voltage is low, it’s likely the battery.

Whining or Grinding from Under the Hood: There are bearings inside the alternator that allow the shaft to turn smoothly at high rpm. If these bearings begin to fail, there will be a grinding/rumbling noise coming from underneath the hood. A whining noise can be heard when the voltage regulator inside the alternator goes bad, and commands the alternator to charge more than necessary. Both of these conditions require alternator replacement.

Dash Warning Light: If you’re driving, and the red battery light comes on, it’s usually the alternator. By all means, check the battery first, but this is typically a sign of a bad alternator.

Electrical Failure: If, while driving, you notice devices like your wipers, power windows, power locks, radio, etc., working slowly, or not at all, it’s time to hit the auto parts store for an alternator.

The alternators on Dodger Challengers vary by year and engine size. Below is a table listing which years and engine sizes share the same upgraded alternators and their amperage ratings:

As of today, there are not yet any listings for aftermarket upgraded alternators for 2017 and 2018 models. Be sure to keep searching, as they should be available soon. They should be expected to be of similar amperage rating as those listed above.