A motor vehicle battery provides a reservoir of electricity that powers the car’s engine and electric accessories. It also helps stabilize voltage spikes that occur when turning on or off accessories that draw a lot of energy.
When choosing a battery, look for the BCI or battery group number in your owner’s manual to help you select one that fits your vehicle and its power requirements.
Primary cell
The battery provides power for a vehicle’s accessories such as the air conditioning and wipers. It also supplies energy for the engine during start-up and ignition. It works in partnership with an alternator to control the car’s electrical system.
In a primary cell, the anode is composed of highly mobile metals that can donate electrons to the circuit. The cathode is made of less-mobile metals that can accept electrons from the circuit. The electrolyte solution in a primary battery contains water and sulfuric acid.
The battery has a plastic case and heavy terminals, plated with lead to resist corrosion, that connect the positive and negative plates of each cell. It also has short, heavy straps that prevent the plates from touching and causing a short circuit. A woven sheet or plastic separator is placed between the plates to prevent a chemical reaction that would produce gas. The battery also has vents that release hydrogen and oxygen gases when it is overcharged or overheated.
Secondary cell
Secondary batteries are rechargeable battery cells that can be used, discharged, and then restored to their original condition by reversing the current flow (charging). They are typically cheaper than primary batteries on a per-unit basis but may cost more in the long run because they need to be replaced.
Car batteries provide reservoir of electricity from which the engine can draw, as well as power accessories like the radio. It also helps stabilize voltage spikes caused by turning on and off accessories that pull a lot of energy.
A battery is made up of plates that conduct an electrochemical reaction in a liquid electrolyte, often sulfuric acid. Over time, the lead and lead oxide in a battery can oxidize to form lead sulfate crystals. If these crystals are not re-converted to lead and lead oxide, the battery cannot accept a charge and will lose capacity. A battery can be topped up with distilled water to help prevent this sulfation.
Flooded lead-acid
Flooded lead-acid batteries are the workhorses of automotive and industrial trucks. They provide a burst of power that starts engines and runs electronics. These batteries use plates made of lead alternating with plates of other materials immersed in an electrolyte solution of one-third sulfuric acid and two-thirds water. When the ignition is turned on, it causes the acid to react with the active material on the battery’s plates, creating electricity.
Flooded batteries require regular checks and maintenance to reach their maximum lifespans. You’ll need to check the electrolyte level and top it up with distilled water when necessary.
Flooded lead-acid batteries are also known as wet cell or flooded batteries. They can be more affordable than sealed batteries, but they’re not as durable as other options. They also have one of the shortest lifespans and are prone to leaks. However, you can reduce the need for replacement by avoiding excessive discharges. This can be done by following the manufacturer’s recommendations for charging and discharging.
Lithium-ion
Lithium-ion batteries power a range of electronics from portable computers, cordless tools and mobile phones to hybrid and electric cars. They have double the energy density of lead-acid batteries and are lighter and smaller.
They are also maintenance-free – no liquid electrolyte needs to be added, and they are less susceptible to damage by heat or cold. They’re also more environmentally friendly as there are no acid spills or dangerous vapors, and they can be recycled.
A battery pack for an EV consists of many lithium-ion cells that are fastened together to create the 12 volts needed to drive the motor vehicle. It is then sealed in a protective case, with terminals that connect to the motor and to the battery management system that monitors and regulates it.
The negative electrode of a Li-ion cell is usually made of graphite, while the positive is typically made of nickel cobalt oxide (NiCoMn). Both are relatively cheap and durable materials. The chemistry of the battery relies on the use of an electrolyte, usually non-aqueous and composed of alkyl carbonate solvents such as ethylene carbonate and propylene carbonate, to form a solid interface between the electrodes.