Can your alternator overcharge your battery

Signs of damage to an overcharged battery include swelling and cracks to the battery case caused by a buildup of gas and a loss of electrolyte fluid inside the battery. A battery will usually feel hot to touch after it has been overcharged.

Some batteries may even start to leak if they have been overcharged for a long time. On newer vehicles, an overcharging alternator will trigger one or more error codes that will usually cause a check engine light on the dashboard.

As outlined above, modern vehicle charging systems are controlled and monitored by the ECU. If the ECU detects a problem with the alternator such as overcharging it will record this in memory and take the appropriate action necessary to protect the rest of the charging system and battery. This error is triggered when the ECU detects a high voltage somewhere in the charging system.

It often points to an overcharging alternator, but can also be caused by problems elsewhere such as a bad voltage regulator, bad battery wiring, or corrosion at the battery terminals. Another symptom of an overcharging alternator is damage to the electrical system in the vehicle. This commonly starts with fuses and bulbs that repeatedly blow due to voltage surges. Over time, an overcharging alternator can damage the wiring looms in the charging system, causing them to become burnt or brittle.

This can sometimes lead to vehicle fires if the alternator is not repaired or replaced. If the battery is constantly being overcharged it will drastically shorten its lifespan. Traditional, sealed car batteries contain a sulphuric acid and distilled water electrolyte that facilitates repeated charging and discharging of the battery. Continuous overcharging when the engine is running causes this liquid inside the battery to heat up to the point where a chemical reaction occurs that releases hydrogen and oxygen.

However, loss of the electrolyte reduces the ability of the battery to discharge and recharge properly. Newer vehicles often use AGM battery technology where the acid electrolyte is bound to a fleece textured mat that helps to protect the electrolyte from damage caused by overcharging. This also allows for more frequent charging and discharging. A basic alternator test can be performed using a multimeter. Using a diagnostic tool such as an OBD II reader will give you access to stored error codes and some can allow you to record the voltage output of the alternator in real-time under varying conditions.

This is usually somewhere between 13 and 15 volts when the engine is running, but it can be higher or lower on some vehicles. When checking the voltage output of the alternator you should try to get a reading at the alternator terminals instead of at the battery terminals. This will give you a more accurate reading without wiring or auxiliary device voltage loss.

Testing the alternator is as simple as starting the engine and measuring the voltage by placing the tip of the multimeter leads on the corresponding output terminal on the alternator.

That being said, a specific sequence of events could potentially lead to a big kaboom, with overcharging being one of those events. But the good news is, with the right car battery care, overcharging can be a thing of the past. However, older batteries have more dramatic side effects. As a car battery overcharges, the sulfuric acid and distilled water mix starts to boil. This gas can either swell up the casing or start seeping out through small fissures.

This alternator provides the battery with a steady, controlled electrical charge while the car is running. However, like most devices, alternators can fail, and when they do, unregulated electrical charges will continue to power up the battery, leading to an overcharge. Of course, car battery overcharging can also happen because of human error, like using aftermarket battery chargers without knowing how to properly operate them, using high amp settings, or setting incorrect voltage, all of which can overcharge a car battery.

Most of the time, car battery overcharge happens when a car owner leaves their charger unattended throughout the night. Here are some of the more common causes of overcharging your car battery:. Just like what its name suggests, a voltage regulator regulates the amount of electricity that goes into a battery. More specifically, a voltage regulator makes sure that the voltage flowing into the battery does so at a steady rate, ensuring that the battery gets the right amount of energy.

When a voltage regulator breaks, the amount of electricity that goes into the battery remains unchecked, meaning it could either be too little or too much energy flowing into it. More often than not, if your voltage regulator is broken, so is your alternator. Like mentioned earlier, the alternator helps the battery receive the right amount of energy while your car is driving.

It does this by generating electricity that it sends to the battery, ensuring that your car battery always has enough energy to run the electrical components of your vehicle i. When an alternator breaks, more often than not it generates too much electricity, thus leading to a car battery overcharge.

A broken alternator can lead to the battery plates shedding off the protective coating it has because of the heat; at best, it just loses its ability to charge, at worst, it could damage or compromise the overall structure of the battery.

Continuously overcharging your car battery will definitely decrease the general lifespan of the battery, meaning that the battery will hold less electricity every time it charges.

Alternators can break for several reasons, but more often than not, there are two main causes: a failed voltage regulator or a problematic battery in itself. In addition to charging the battery, the alternator powers the headlights.

If you have a failing alternator it is likely that your headlight will start to lose power. They may flicker or go very dim. Your car needs electricity to run in addition to gasoline.

Electricity creates the spark that ignites your gasoline and creates power to your engine. The alternator and battery supply electrical charge to your spark plugs. So, if your alternator is failing, your car might stall or have difficulty starting. When your alternator goes bad, other electronics in your car might malfunction, too. These include your dashboard lights, radios, windows, etc. The bearing in your engine might break, which would cause a rattling or growling noise.

Of course, if you hear any kind of strange noises from your car you should have a specialist perform a diagnostic.

This would be the most obvious. Your battery will eventually die as your alternator fails to charge it. When replacing a dead battery, you should definitely have your alternator checked as well. Normally there is a high reading for the ignition voltage, and then it settles around 13 or 14 volts. If the voltage reading is 15 volts or higher, get your vehicle checked.