The Care and Feeding Of The Power Source Of Your Car
Though it is now changing with the advent of newer vehicles, the vast majority of car batteries currently on the road are still part of the lead-acid battery group. These batteries constitute six galvanic cells – see the ‘Anatomy of a car battery’ diagram for details – laid out in series. Each cell delivers 2.1 volts of electromotive force that, when combined, produce the common 12.6-volt automotive battery (commonly advertised as 12-volt). One of these 12-volt batteries is powerful enough to keep a car’s systems running for years with the proper care, and larger diesel vehicles may employ two.
Each galvanic cell consists of a series of lead and lead dioxide plates submerged in an electrolyte solution – a mix of sulphuric acid (35 percent) and water (65 percent). This acidic bath triggers a reaction with the lead dioxide plate (the positive electrode), which produces ions and lead sulfate. These sulphuric ions then react with the adjacent lead plates (the negative electrode) to produce hydrogen ions and lead sulfate.
This chemical reaction, in turn, generates electrons that can flow out via conductive terminals as electricity to power essential functions. The reaction is not permanent, with the lead sulfate reforming into lead dioxide and lead when the battery is recharged. Over time, the battery’s efficiency will deplete, with most working optimally for about 3-4 years.
Why Does A Battery “Die”?
A battery is just an ongoing chemical reaction under the hood or in the trunk of our cars. The interaction of sulfuric acid with the surface area of the lead plates is at the heart of a battery’s ability to create, store, and release energy. Basically, a battery can store and supply energy if enough of the active plate material is available to allow an energy transfer to occur naturally. Batteries don’t give up the ghost or fail without warning. Generally, they will be showing plenty of signs and symptoms before failure. Those signs might be a slow cranking over of the engine, hesitation to start, a clicking noise before starting, and warnings on the dash about the battery state or condition of some newer cars.
Batteries are usually the first to suffer from the cold—losing 35% of their strength at 30° F and 60% at 0° F. Temperature also affects charge and discharge rates. A cold battery will charge and self-discharge slower than a warm battery, but will also exhibit lower capacity. When it’s cold outside, sulfating buildup in combination with the slow down of the chemical reaction within the battery will rob the battery’s ability to provide operational power and is only exaggerated as vehicle fluids thicken due to the cold. This cold condition causes even more available power and capability to be taken from the battery to start the vehicle, so the battery has to work harder than normal to provide additional power demanded by the vehicle and, as a result, realizes a further reduction in voltage, causing a faster buildup of sulfates on the lead plates.
A Long Life
In theory, batteries should last many years, but they usually don’t because of a series of detrimental problems caused by “excessive sulfating buildup” that leads to premature battery failure. It can take up to twice as much current during cold temperatures to start a vehicle as under normal conditions. A poorly maintained battery just doesn’t stand a chance. Extremes of hot and cold can also take their toll on a battery.
Also, keep in mind that a battery that is allowed to remain in a discharged state for an extended period of time, creates high levels of plate sulfating that have a lasting effect on the battery’s capacity. In other words, a dead or deeply discharged battery rarely bounces back to its full potential and will always have reduced capacity, even if it is relatively new. This is why we always recommend some sort of battery tender, or trickle charger on batteries during periods of extended storage, two or more weeks.
Need More Help?
Please contact us if we can help in any way with service on your Audi, BMW, Land Rover, Mercedes, Mini Cooper, Porsche, or other European imports. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969, or you can email our Service Team at email@example.com.
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The Atlantic Motorcar Center Service Team