The automotive battery comes in different shapes and sizes. The most important function is to start the engine. It is also responsible for powering some of the vehicle's electronic accessories.

The typical automotive battery consists of cells arranged in series. Once the engine has started, the car’s electrical system reverses the current and starts charging the battery through the alternator and regulator.

Most of us have encountered a flat battery. It happens when we least expect it, like in the morning when you are rushing for a meeting with a very important client. To make the situation worse, the vehicle may be automatic, which means push-starting is out.

Lead Acid Battery

The most common automotive battery is the lead-acid, consisting of six cells that give an output of about 12 volts. Each cell consists of alternate plates of a lead alloy grid filled with sponge lead, which acts as the negative (cathode) or coated with lead dioxide (anode). The cell is then covered with a sulphuric acid solution, the electrolyte. The battery can be open or sealed.

An open battery has a filler cap that allows for the checking of the electrolyte level and adjustment of its density. A vent cap is also part of the design, to allow for the escape of the hydrogen gas generated.

The cells are then linked with straps that connect the positive terminal of one cell to the negative of the next cell. Terminals at the top of the battery then connect the battery to the electrical systems, with the negative terminal connected to the vehicle body.

With a sealed battery, there is no need to adjust the electrolyte. There are also low-maintenance batteries that do not require the electrolyte to be adjusted. They use battery plate elements that reduce the amount of water decomposed.

How Do I Look After My Car Battery?

Caring for the battery is fundamental. It involves regular checking (twice a year at least), not just for the electrolyte level (which should cover the cells), but most importantly, for the state of charge and the functionality of the charging system. This should be done by a battery mechanic, who does several checks, including a density check, using a hydrometer.

The state of charge is measured using a battery hydrometer. The hydrometer measures the density of the electrolyte by measuring its specific gravity. The higher the density the higher the state of charge of the battery. When the density is low, it can be corrected by adding battery acid to the electrolyte.

Most drivers, vehicle owners, and mechanics do not have access to a hydrometer. This is why it is necessary to ensure the battery is checked by a technician who has the right equipment.

The other battery maintenance issue is the blue stuff (hydrated copper sulfate) on the terminals. It interferes with the contacts, and therefore the flow of current. The copper sulfate can be removed in various ways. Most people use hot water to dissolve sulfate. However, it can be removed more effectively using baking soda or vinegar. This you can do by yourself, and you can check weekly, especially if you drive for short distances.

Lastly, also check that the terminals are well secured and lubricated. Simple lubrication can be done with petroleum jelly.

Take care of your battery, and it will take care of you. Expect your well-maintained battery to last at least three years.