Your battery stores power and provides electrical current to start your car’s engine and operate other onboard functions. There are many factors to consider when selecting a battery including battery group, cold cranking amps and size.
Choosing the right battery starts with understanding your car’s needs. You can find this information in your owner’s manual and at auto parts stores or dealerships.
Types
The different types of car batteries are designed for specific power needs. Some are better for starting the engine and others, like the absorbed glass mat (AGM) battery, are best for powering other components like the radio and lights.
The most common type is a standard lead-acid battery. These have rows of cells with a lead dioxide plate and a lead plate that are submerged in sulphuric acid. A chemical reaction between the plates generates electrons that produce a direct current that can crank the engine. The battery then stabilizes the electric current with a regulator.
Some standard batteries have vents and removable caps, while others are sealed for a more permanent solution that isn’t susceptible to spills. The latter are called VRLA or valve-regulated lead acid, dry cell, non-spillable or gel batteries. The AGM battery has a fiber glass mat separator that absorbs the electrolyte, so it doesn’t need to be topped up. It has pressure-activated relief valves that open if it overheats during recharging.
Functions
The function of a battery is to convert chemical energy into electrical energy. When you start your car, the battery supplies voltage to a starter motor and other electric components. The battery also acts as a backup to power your lights, radio or GPS when the engine isn’t running.
The voltaic cell of the lead-acid battery contains two plates (Pb and PbO2) submerged in an electrolyte—in this case, a 35% solution by weight of sulfuric acid, H2SO4, in water. A series of chemical reactions at each plate produces ions that transfer across the electrode-electrolyte interface, creating an electric current.
The ions that were close to the electrodes initially have been depleted by these chemical reactions. So, after your five-minute drive, the ion density in the bulk of the electrolyte is rather low. After a long wait, the ions that remain spread out to a more uniform distribution, as shown in Figure 7.12(a). At this point, there is enough of a charge to start your car.
Maintenance
Many standard lead-acid batteries require recharging on a regular basis to maintain their lifespan. Depending on the battery type, this may be done through connecting it to a quality voltage maintainer or simply driving your car regularly (which helps the electrolyte levels recharge).
The terminal connections should be kept clean to ensure that the battery can provide power as efficiently as possible. Corroded terminals can hinder the flow of electricity, so they should be cleaned with a mixture of water and baking soda. After cleaning, apply petroleum jelly or a commercial terminal protectant to minimize future corrosion.
Additionally, it is important to make sure that the battery tray is secure and there are no cracks or rust. This prevents vibration that can cause internal damage and reduce the battery’s lifespan. Standard, unsealed wet-cell lead-acid batteries need to be topped off with battery fluid from time to time as well. It is recommended that this be performed once per month.
Warranty
Many battery manufacturers and resellers offer warranty plans on their products. These typically come in two flavors: free replacement and prorated replacement. Under a free-replacement plan, the vendor will replace a defective battery at no charge during the first two years of service. After that, they will charge a pro-rated fee for any subsequent replacements.
Regardless of which type of battery you purchase, it’s important to handle it with care. Physical mishandling, such as dropping or bumping the battery, can void any remaining warranty coverage. Additionally, installing a battery in a vehicle or application for which it is not designed can also void a warranty claim.
It’s also a good idea to keep the receipt for any battery purchases you make. Warranties are usually honored and serviced by the retailers that sell the batteries originally. Purchasing batteries online is an excellent way to get a great price, but it can be problematic when the original warranty comes into play.