A motor vehicle battery is a complex piece of automotive equipment that’s vital for the power of your car. It’s no surprise that this part is one of the most popular causes for breakdown calls.
Most batteries have different standardized designations depending on the manufacturer and the location. These include battery group, terminal type and voltage (6V or 12V). Also important is Cold Cranking Amps (CCA). This indicates how much power the battery can provide at a low temperature.
Types
There are several car battery types, and the type you need depends on your power needs. Classic wet lead-acid batteries (sometimes called SLI – starting, lighting and ignition) are very affordable and get the job done for most standard vehicles.
They consist of six cells with alternate plates of a lead alloy grid (cathode) or sponge lead (anode). A heavy cast-on strap prevents the positive and negative plates in each cell from touching and shorting out. The cells are filled with a solution of sulfuric acid and water (the electrolyte).
Car batteries with an Absorbed Glass Mat or AGM design use thin glass fibre mats to hold the electrolyte inside. These batteries are maintenance-free and can withstand higher temperatures and shocks. Lithium Ion batteries power most EVs, HEVs and PHEVs. These are very compact and cannot be topped up, but they offer greater power for their size. They also recharge faster and last longer than other types.
Maintenance
Whether you have an old fashioned lead acid battery or a lithium-ion electric one, you can extend its life by observing basic maintenance principles. For example, check the case and terminals for cracks, dirt, loose or broken components or signs of corrosion.
When working on a battery, wear rubber gloves. A lead acid battery is filled with sulfuric acid, and if it spills onto you it will burn your skin and eat through your clothes. Spilled acid should be neutralised with water and washed off your skin immediately.
Batteries have a limited lifespan, and their deterioration can accelerate if they are frequently used for short trips or left uncharged in cold weather. Routine testing with a battery tester or by an automotive repair shop can help you to determine when the battery needs replacing. A good test should measure the battery’s state of charge, which is indicated by a multimeter reading. To read a battery’s state of charge, disconnect it from the vehicle, remove its black (minus) terminal first and its red (+) terminal last, keeping the leads away from moving or rotating components.
Replacement
The battery is the heart of the electrical system and a car can’t function without it. It provides the electricity that fires up a vehicle’s engine and keeps electric-powered accessories like the radio and air conditioning running.
The most common types of auto batteries are standard wet cell batteries and absorbed glass mat (AGM) batteries, both using lead-acid technology. The former have vents that allow for the release of corrosive gases and steam, and have removable caps for adding water. The latter have a fiberglass mat between the lead plates to absorb the battery’s chemical solution, and are typically more durable and efficient.
Lithium-ion batteries are also available and offer improved efficiency, lower maintenance and a longer lifespan than traditional lead-acid models. However, they can be dangerous to handle as they are filled with sulphuric acid, so it’s always best to leave these kinds of batteries for qualified technicians.
Safety
A battery protects the electrical system by storing electricity and regulating voltage. It can also absorb power spikes and instabilities that could otherwise damage solid-state accessories like computers and ignition systems.
A quality lead-acid model can last a long time, but it’s not always the best option for vehicles with more demanding electrical needs. An alternative is a VRLA (voltage-regulated lead-acid) battery, which has absorbed glass mats in each cell that prevent the loss of electrolyte. This design gives the battery a longer lifespan but it can be expensive.
Another way to extend battery life is by regularly checking and cleaning the positive and negative posts for signs of corrosion. Corrosion often occurs when the battery isn’t used often enough, or it’s parked in harsh weather conditions. Practicing good driving and repair habits can help too. For example, disconnecting devices that draw electricity when the vehicle is parked can cut down on battery drain. The battery can then recharge when the vehicle is in use again.