Your Vehicle's Battery - How it Works & How to Maintain it

Team BlueStar Inspections

The primary purpose of the battery in your vehicle is to provide electrical energy to crank the engine during starting. Contrary to what many people think, a battery is comprised of stored chemicals, not electricity. Two different types of lead in a sulfuric acid and water mixture react with one another to produce an electrical pressure. This electro-chemical reaction changes chemical energy into electrical energy, which allows you to easily start your vehicle.

Battery electrical energy is used to operate the starter motor and to provide current to the ignition system when you turn your key or press the start button. It is also used to operate accessory systems such as the radio, entertainment system, technology access ports, power windows, power seats, power door locks, and lighting. The battery electrical energy may also be used when a vehicle's electrical load requirements exceed the supply from the charging system.

Additionally, the battery also serves as a voltage stabilizer by absorbing unexpected voltages from the vehicle's electrical system. This helps protect electrical circuits and components from damage that may result from high voltages. The battery also provides emergency electrical energy for ignition, lights, and accessories if the vehicle's charging system fails. This reserve capacity of the battery may help you get to safety in the event that your charging system fails.

Batteries can fail prematurely due to a number of conditions which can be prevented by a thorough battery inspection. These conditions include corrosion, low fluid level, a faulty charging system, a poorly secured battery, excessive heat, and repeated cycling from fully charged to fully discharged, or dead. Corrosion on the positive and negative terminal ends and cable connections increases electrical resistance, which can reduce the available voltage and effectiveness of the charging system.

A low fluid level in the battery cells can expose active material on the plates and cause this material to harden and resist the electro-chemical reaction. Low fluid level may be caused by electrolyte evaporation in conventional batteries with removable vent caps, lack of battery maintenance, not adding distilled water when needed, a cracked battery case, a charging system producing higher than normal voltage, and overheating of the battery. Because batteries emit hydrogen gas while charging, the battery case can't be completely sealed. Maintenance free batteries have small vents on the side of the battery, and the gases emitted have to go through baffles to escape. During this process, the liquid condenses and drops back into the battery. There is no need to replenish or add distilled water to maintenance free batteries. A faulty charging system can also damage the battery. Undercharging of the battery allows sulfates to harden on the internal plates which will weaken the chemical mixture, also known as the electrolyte. Overcharging can cause the battery to die, overheat, lose fluid, swell, and even explode.

A poorly secured battery can create excessive vibrations which can loosen connections, crack the battery case, damage internal battery components, and may cause the battery terminals to come in contact with metal parts of the vehicle and short out the electrical system.

Excessive battery heat will damage your battery. Battery heat is generated in two ways. The ambient temperature of the area surrounding the battery can reduce the life of the battery if it is too high. A charging system producing higher than normal voltage, usually 14.6 volts or more, can generate excessive heat within the battery and damage it.

A battery that regularly goes dead due to an excessive parasitic draw or drain in the vehicle's electrical system will also fail prematurely. Repeated cycling from fully charged to fully discharged will reduce the capacity and life of the battery.

All batteries require routine maintenance to ensure the battery is in good working condition. When servicing or testing a battery, safety should always be your first concern. Gloves and safety glasses should be worn. It is a good idea to remove any metal jewelry or watches. Remember, the battery contains sulfuric acid. It will burn your skin, eat your clothes, and can damage the finish of your car.

Be careful when using metal tools near the battery and making contact with the battery terminals. Never lay tools on the battery. You should always remove the ground cable first. When reconnecting the two battery cables, the ground cable should always be connected last. It is important to never reverse the polarity of the terminal connections. The positive connection must always connect to the positive battery post, and the negative connection must always connect to the negative post. Remember, disconnecting the battery will erase the memory of the vehicle's computers and other electronic devices and can temporarily impair the vehicle's memory in relation to running optimally.

A visual inspection of the battery is a great place to start. Inspect the battery for any leaks, cracks, or bulges in the case. Leaks will usually be made obvious by the presence of corrosion and acid reacting with whatever it touches. Remove the terminal connections, and use a mixture of water and baking soda to clean battery corrosion. A wire brush or an old toothbrush can be used to assist with cleaning the connections.Inspect the battery to make sure it is securely in place. If the battery is equipped with vent caps, carefully remove the caps and inspect the electrolyte level. If necessary, add distilled water to each low cell, but do not overfill. The proper level is about a half an inch above the cell plates or no higher than the bottom of the fill opening.

An ASE certified technician can fully test and service your battery, thereby giving you the peace of mind to drive without the fear that your battery may fail. Have your battery inspected, tested, and replaced if necessary, every time you have routine service performed on your vehicle. When properly maintained, your battery will provide at least five years of service and start your vehicle hundreds, and even thousands of times.