Today’s automobile batteries are the power source that collects and stores the electricity a vehicle needs to operate reliably. Automobile batteries consist of a plastic casing filled with sulfuric acid, electrolyte and lead plates that are capable of lasting many years if properly cared for.
Modern automobile batteries consist of six cells created by lead plates that are each capable of holding 2.1 volts, making the battery capable of holding 12.6 volts at full capacity. Half of the lead plates in a battery are coated with lead dioxide (anode) which causes a chemical reaction with the sulfuric acid that creates the electricity the battery will use to start the engine. Each time the battery is discharged lead sulfate develops on the plates, and when it is recharged it reforms into the original lead dioxide coating. This cycle continues for the entire life span of the battery.
Starting the vehicle takes just 2-4 percent of the batteries total charge and is its most important function in the vehicle. Discharging them more than half of their charge can reduce the life of the battery drastically due to the amount of lead sulfate created on the plates. It is important to slowly charge a battery that has not been in use for a long time or that has less than 20 percent charge.
Nearly all modern day batteries are maintenance free. However, here are a few things to keep in mind:
- Heat is a batteries’ worst enemy. Make sure all factory heat jackets/shields are reinstalled when removing/testing a battery.
- Keep battery terminals clean and free of corrosion which can cause resistance and poor performance. Coat with dielectric grease as a preventative measure.
- Make sure vent tubes are installed if equipped and be aware of rotten/sulfuric smells around the battery. A rotten smell is usually sure sign the battery is nearing the end of its life. This is due to the internal corrosion of the battery. Test/replace as necessary
When diagnosing a starting issue on a vehicle the battery is the most practical/popular starting point. To test the charge of a battery (its voltage) a multi-meter can be used. Remove the battery cables and set the multi-meter to DC 20 VOLTS. Next connect the positive and negative probes to the battery and the voltage reading will display. If the battery has less than 12.4 volts it should be charged, if it has less than 11.9 it is dead and will need to be slow charged to reverse the damage. Note that depending on the age of the dead battery the damage may not be reversible with a slow charge. To perform a “load test” a battery tester will be required. A battery tester will apply an electrical load to the battery to assess its performance. A reading below 9.6 reveals a bad battery. Some battery testers will test the charge and assess the performance of the battery in one simple test.