Common Symptoms of a Failing Battery

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The battery powers the vehicle’s electrical system. Its primary function is to supply power to the starter motor to rotate the engine and begin the combustion process. The second function of the battery is to provide electrical power to the vehicle when the alternator does not provide enough output. When a battery fails, a vehicle can be left disabled. A weak battery most commonly presents itself in the form of being unable to power the starter.

This article highlights the common symptoms of a failing battery, providing insight into potential problems and their underlying causes.

What Causes Battery Failures?

Age: Automotive batteries have a limited lifespan and degrade over time, even with proper maintenance. As the battery ages, it loses its ability to hold a charge or put out cold cranking amps.

Improper charging: Overcharging causes excessive off gassing and high internal heat, leading to the removal of active material from the plates and the oxidation of the positive plate material. Conversely, undercharging causes sulfation, reducing battery capacity. Both conditions cut short the normal expected service life of an automotive battery.

Corrosion: Corrosion on the battery terminals and connectors restricts the flow of electricity and causes excessive resistance, resulting in poor charging system operation.

Extreme temperature: Extreme temperatures cause chemical reactions. With higher temperatures, corrosion is accelerated in the battery cells. With lower temperatures, battery performance drops dramatically.

Common Symptoms of a Faulty Battery

Illuminated battery warning light

It is normal for the battery warning light to illuminate when you first place the ignition in the Key On Engine Off position, (just before START-UP.) If the warning light remains illuminated after the engine is running, a potential issue with the vehicle’s charging or electrical system is indicated. The battery warning light may also illuminate as the vehicle is being driven down the road, again pointing to an electrical or charging issue. If you observe this indicator along with any symptoms other than the START-UP procedure, it suggests that your battery may need to be tested and if faulty require replacement.

Electrical Problems

When a failing battery loses charge while the engine is operating, the vehicle’s control modules may “shed” functions to extend battery range. In short, this means the vehicle may stop powering the A/C system, heated seats, or other unnecessary “comfort” systems to ensure that necessary systems such as ignition, airbag, and ABS are supported.

As a battery loses charge, headlight output may begin to dim. Instrument Panel Cluster illumination may dim as well. When assessing a battery’s state of health, it is important to monitor dynamic values such as alternator output, battery voltage, and Engine Control Module (ECM) voltage to identify which system is contributing to battery health.

Trouble Starting the Vehicle

When attempting to start the vehicle, the engine may be noticeably sluggish. This indicates a potentially weak battery. Difficulty starting a vehicle is not limited to the battery itself. A weak alternator or resistance in the starter circuit can also contribute to a weak battery.

A weak alternator will not fully charge a battery. A faulty starting circuit can place extra current draw on a battery to start a vehicle. However, during start-up if you only hear clicking when you turn the key or if the engine turns over slowly and takes longer than usual to start, it's advisable to have the battery examined.

Sulfuric Smell and Swollen Battery Case

A battery may leak sulfuric acid. A leaking battery often gives off a pungent odor of sulfur, similar to rotting eggs. Prompt replacement is crucial to prevent further damage from acid leaks, which can corrode other engine components if left unchecked. This sulfuric smell is often coupled with a swollen battery case, bulging at the sides.

Identify A Faulty Battery with the Innova Scan Tool

The Innova Scan Tool quickly retrieves Diagnostic Trouble Codes (DTCs) and provides descriptions for the retrieved DTCs as well. When investigating and troubleshooting battery issues, the 5610 Scan Tool supports ECU Voltage, which often mirrors battery voltage.

The 5610 can monitor dynamic Parameter Identification Data (PIDs) in vehicles that support generator voltage output, battery voltage, and battery current sensor PIDs both in OBD2 Diagnostics and OEM Enhanced Live Data. These PIDs are very effective at identifying which system or systems are operating normally. Additionally, the 5610 has a built-in battery test and alternator test function for testing the battery and alternator through the Data Link Connector (DLC) at the driver’s seat without opening the hood.

Please visit us at innova.com/support or pro.repairsolutions.com/Support for additional information.

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