Should The Alternator Get Hot?

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What does a hot car alternator mean? Is this a normal experience or does this spell of an underlying problem? Many car owners get worried when they noticed their alternators getting hot, especially to the degree of causing a burn injury when touched. 

So, should the alternator get hot? The alternator, similar to any other car part is expected to heat up to a certain degree as a result of usage.

Some degree of hotness should be expected from any working car part after running the car engine for a considerable time duration. However, there is a certain degree of hotness an alternator possesses that could spell an underlying problem.

An alternator that is as hot as causing burn injuries should be queried for malfunctioning. Sometimes, this could be as a result of a bet that is over tightened or from overloading the alternator with too much work such as using it with a flat dead battery and trying to resurrect the battery with it.

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why do alternators get hot?

An alternator that always gets exceedingly hot every time the car is driven may eventually begin to malfunction with time and require to be replaced, it is best therefore to find out the cause of the hotness to avoid alternator failure.

One of the most popular causes of alternators getting hot is when the alternator is overloaded, as seen in the case of using the alternator to charge a weak battery.

Weak batteries, as well as flat dead batteries, require a huge amount of current to bring them back to the world of the living, using your car alternator to do this may be too much work for the alternator, causing the alternator to overheat.

A weak or flat dead battery should therefore not be used with the alternator, rather, it should be first placed on a battery charger which will bring up its charge before using it with the alternator. Recharging a battery too weak to get the car started may be a cause of overloading the alternator.

Alternators naturally get hot from working at a regular load, hence, the need for the alternator fan. However, in the case when such a fan does not work efficiently, the alternator cooling system is defective and may cause the alternator to get overheated.

Your car’s voltmeter will tell you the voltage output of your car battery, this will help you tell when the battery is too weak for the alternator and should be charged directly first before use.

Once the voltage output of the battery is considerably below the normal range, the car will refuse to start and have to be jump-started.

Sometimes, the battery is defective and cannot hold down the current inflow from the alternator.

So, even though the charging efficiency of the alternator is normal, the battery is like a leaky bucket that cannot hold the water poured into it.

In this saturation, the alternator can get overheated from working too much and for too long.

So, alternators do get hot similar to what you will find the other car parts when your lift the hood of the car after driving for some time, however, there is a certain degree of this hotness that is considered abnormal for the alternator.

The commonest answer to why an alternator gets hot involves one of two things, this could be as a result of factors to impede the outflow of the current that leaves the alternator through its diodes as well as the wire windings, or as a result of a frictional force that builds up the alternators bearing or belt. Either of these can explain the heat.

Possible causes of alternator getting hot

The job of the alternator in a car is to supply the current that recharges the car battery and runs the other electrical aspects of the car. If however, the alternator starts getting hot all the time, this is not a normal finding and could be a result of the following causes

Faulty belt

Belts work with friction and therefore get worn out with time. The belt must be checked to make sure it is not worn out as this is one of the causes of the alternator overheating.

Battery compatibility

When you have a vintage car and need to get a new car battery for your car, you must make sure the new model of car battery you are getting for your car is compatible with the car.

Incompatibility of the battery model with the working system of the car could lead to the alternator getting hot as it fruitlessly tries to charge the battery to no avail.

Lack of voltage

The voltage out of your car battery is crucial to how long and how hard the alternator has to work. When the output is poor, it could be a result of a faulty fuse or a wiring problem.

Run a diagnostic to find out where the etiology of the problem is coming from and correct this to avoid getting the alternator overheated and consequently failing.


The vehicle overheats, and components parts of the car are affected including the car alternator. To avoid such incidence, make sure to have adequate coolant water for the engine to stay within the operational temperature range. 

A battery with an immensely low voltage output is always one of the commonest causes of alternators overheating.

Worn-out brushes

The alternator brushes are important components of the charging system as they subserve the function of power transfer.

When these brushes become worn out, the efficiency of the power transfer is greatly decreased. The alternator in this instance becomes overworked as a result and may get hot.

Car owners who take their car for regular checkups and services are likely to catch up with a worn-out brush or similar event before they become a problem.

How to fix a hot alternator

For a problem that occurs frequently, it is economical to learn inexpensive and easy ways of fixing such a problem without necessarily having turns of experiences or sophisticated tools.

So, when your alternator gets hot, what do you do, or do you simply cry to your mechanic about it? Here are some of the easy and inexpensive ways to fix a hot alternator.

  • Cooling

Irrespective of whatever repair process you want to carry out, the alternator must be allowed to get cool before touching it in order not to get yourself hurt.

Given that the alternator became hot from the high amount of electrical current drawn from it by the load placed on it, ensure to turn off every single car accessory powered by the car battery.

It is better saved than sorry, wait for the alternator to cool down, there is no need for the rush, except if you plan on feeling sorry for yourself. 

  • disconnect the alternator from the battery

news flash; cars can run without their battery! When a car is turned on, the job of the car battery is done. The car battery can be removed without causing the engine to go off. the alternator can therefore be disconnected from the car battery after the battery has been used to turn on the engine. 

When this is done, no amount of electricity flows from the battery to another electrical component of the car.

Their battery is therefore not discharged and the alternator does not need to work to recharge it. This buys it time to get cooled from the overheating. While this may be a temporary fix, it buys you time until you can see a mechanic.

  • Rest the car engine

Alternators can get hot from being overworked, such as when the car is driven for a long duration. If the cause of the overheating is a result of overworking, then a simple solution will be to allow the vehicle to take some rest, preferably under a shade, protected from the direct sunlight.

What will happen to an alternator that is too hot?

Eventually, an alternator that is constantly too hot will experience an untimely failure and will need to be changed before it caused more problems. Here are some of the ways to find out if the alternator is failing

  • The car headlight may become dim or excessively bright
  • The car battery may become dead
  • Electrical accessories in the car malfunction
  • It becomes tough to get the car started. The car never starts on a single attempt.
  • Noticeable whining noise coming from the car.
  • The dashboard shows a battery warning sign
  • You may begin to hear a smell of a burning wire. This is perhaps the commonest way of finding out the alternator is overheating.

Should The Alternator Get Hot – Conclusion

Learn how to maintain your car’s electrical system to avoid falling into the problem of an overheating alternator as this may cause more problems for another car part.

Learn to keep your car battery clean, check the alternator regularly, maintain the car battery and prevent corrosion problems.

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