Car batteries tend to last for several years, but lifespan depends on how they are used. The typical car battery, driven every day, properly charged, and never deep-cycled, could last upwards of 7 years, but that’s a best-case scenario.
Most maintenance-free (read: replace on death) car batteries tend to last 4 to 7 years. Short car battery life, less than 3 or 4 years, can be related to several different problems, such as lack of use, corrosion, excessive deep cycling, electrolyte evaporation, damage, or charging problems.
Every time a driver turns the ignition key or presses the “Start” button, the starter motor is expected to crank the engine. This mechanism is caused by the 12-V flooded lead-acid car battery, which is standard on virtually every vehicle on the road.
Some cars carry a second battery, and trucks and RVs may carry a battery bank, linking several batteries. Similar batteries can be found in tractors, power equipment, motorcycles, Powersports machines, snowmobiles, four-wheelers, and solar power backup systems, to name a few.
How Does a Car Battery “Die?”
If the Battery Light is Illuminated, it Could Indicate a Problem with the Car Battery or the Charging System.
The are several things that can shorten the life of a car battery, and most of them are preventable. Now, we’re not talking about that “dead battery” that you get when the dome light was left on or the car hasn’t been driven in a month.
Usually, a jump start, booster pack, or battery charger is all that’s necessary to revive the car battery and get the car back on the road, but the damage has already been done.
It’s the accumulation of damage that leads to the untimely death of the car battery, at which point it simply will not start the car. Car battery death, for the purposes of this article, refers to the battery’s inability to hold a charge, usually caused by sulfation.
At its most basic, a car battery is constructed of alternating plates of dissimilar metals, usually, lead and lead oxide (Pb and PbO2), in an electrolyte bath, usually sulfuric acid (H2SO4) in water.
When discharging, the “battery acid” facilitates the flow of electrons, from the Pb plate to the PbO2 plate, generating an electric current, which can be used to start the engine or illuminate the headlights, for example. Because of this chemical reaction, both plates become more chemically-similar and converting fully-discharged car battery plates to lead sulfate (PbSO4), wherein lies the problem.
So-called “soft” battery sulfation occurs practically every time you discharge the battery but, because it is usually immediately recharged, electron flow easily forces the opposite chemical reaction, resulting in dissimilar Pb and PbO2 plates.
If the car battery is left discharged for long periods of time, “hard” sulfation occurs, the formation of lead sulfate crystals. As PbSO4 crystals form, they gradually reduce the available surface area for chemical reaction, reducing the capacity to charge and discharge the battery. Eventually, PbSO4 crystal formation spreads, leading to cracks and short circuits within the battery, rendering it useless.