Automotive Batteries

By SRT-Tom · Oct 19, 2019 ·
  1. SRT-Tom
    Early cars did not have batteries, as their electrical systems were very limited. A bell was used instead of an electric horn, headlights were gas-powered and the engine was started with a crank. Car batteries became widely used, around 1920, as cars became equipped with electric starters. The sealed battery, which did not require refilling, was invented in 1971.

    The Hudson Motor Car Company was the first to use a standardized battery in 1918 when they started using Battery Council International. BCI is the organization that sets the dimensional standards for batteries.


    Cars used 6-volt electrical systems and batteries until the mid-1950s. The changeover from 6 to 12 volts happened when bigger engines, with higher compression ratios, required more electrical power to start.


    An automobile battery is an example of a wet cell battery, with six cells. Each cell of a lead storage battery consists of alternate plates made of a lead alloy grid filled with sponge lead (cathode plates) or coated with lead dioxide (anode). Each cell is filled with a sulfuric acid solution, which is the electrolyte. Initially, cells each had a filler cap, through which the electrolyte level could be viewed and which allowed water to be added to the cell. The filler cap had a small vent hole which allowed hydrogen gas generated during charging to escape from the cell.

    The cells are connected by short heavy straps from the positive plates of one cell to the negative plates of the adjacent cell. A pair of heavy terminals, plated with lead to resist corrosion, are mounted at the top, sometimes the side, of the battery. Early auto batteries used hard rubber cases and wooden plate separators. Modern units use plastic cases and woven sheets to prevent the plates of a cell from touching and short-circuiting.

    In the past, auto batteries required regular inspection and maintenance to replace water that was decomposed during operation of the battery. "Low-maintenance" (sometimes called "zero-maintenance") batteries use a different alloy for the plate elements, reducing the amount of water decomposed on charging. A modern battery does not require additional water over its useful life. A weakness of these batteries is that they are very intolerant of deep discharge- for example, when the car battery is completely drained by leaving the lights on. This coats the lead plate electrodes with sulfate deposits and can reduce the battery's lifespan by a third or more.


    Batteries are typically made of six galvanic cells in a series circuit. Each cell provides 2.1 volts for a total of 12.6 volts at full charge. During discharge, a chemical reaction releases electrons, allowing them to flow through conductors to produce electricity. As the battery discharges, the acid of the electrolyte reacts with the materials of the plates, changing their surface to lead sulfate. When the battery is recharged, the chemical reaction is reversed: the lead sulfate reforms into lead dioxide. With the plates restored to their original condition, the process may be repeated.


    Physical Format

    Batteries are grouped by physical size, type and placement of the terminals, and mounting style.

    Amp Hours (Ah)

    Ampere-hours (Ah or A·h) is a unit related to the energy storage capacity of the battery. This rating is required by law in Europe.

    Cranking Amperages (CCA, CA, MCA, HCA)

    • Cold cranking amperes (CCA): the amount of current a battery can provide at 0 °F. Modern cars with computer controlled fuel-injected engines take no more than a few seconds to start and CCA figures are less important than they used to be. It is important not to confuse CCA with CA/MCA or HCA numbers as the latter will always be higher due to warmer temperatures. For example, a 250 CCA battery will have more starting power than a 250 CA (or MCA) one, and likewise a 250 CA will have more than a 250 HCA one.
    • Cranking amperes (CA): the amount of current a battery can provide at 32 °F.
    • Hot cranking amperes (HCA) is the amount of current a battery can provide at 80 °F. (The rating is defined as the current a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery).
    Reserve Capacity Minutes (RCM)

    A battery's ability to sustain a minimum stated electrical load; it is defined as the time (in minutes) that a lead-acid battery at 80 °F. will continuously deliver 25 amperes before its voltage drops below 10.5 volts.

    Group Size

    Battery Council International (BCI) group size specifies a battery's physical dimensions, such as length, width, and height. Group size is typically based on your vehicle’s make, model and engine type.

    Date Codes

    • In the United States there are codes on batteries to help consumers buy a recently produced one. When batteries are stored, they can start losing their charge. A battery made in October 2015 will have a numeric code of 10-5, or an alphanumeric code of K-5. "A" is for January, "B" is for February, and so on (the letter "I" is skipped).
    Use and maintenance

    Excess heat is a main cause of battery failures, as when the electrolyte evaporates due to high temperatures, decreasing the effective surface area of the plates exposed to the electrolyte, and leading to sulfation. Grid corrosion rates increase with temperature. Also low temperatures can lead to battery failure.

    A vehicle with a flat battery can be jump-started by the battery of another vehicle or by a portable battery booster, after which a running engine will continue to charge the battery. (Note- Challengers, with trunk-mounted vented batteries, have a positive jumper post (red) on the passenger side of the engine bay near the fuse box).


    Corrosion at the battery terminals can prevent a car from starting due to electrical resistance, which can be prevented by the proper application of dielectric grease.


    The primary wear-out mechanism is the shedding of active material from the battery plates, which accumulates at the bottom of the cells and which may eventually short-circuit the plates. This can be substantially reduced by enclosing one set of plates in plastic separator bags, made from a permeable material. This allows the electrolyte and ions to pass through but keeps the sludge build up from bridging the plates.

    Types of Batteries

    There are two basic types of batteries for cars and trucks.

    Starting, Lighting and Ignition Batteries

    The vast majority of automotive batteries are Starting, Lighting and Ignition (SLI) batteries. Like the name implies, these batteries not only help start your car, but also provide power to your ignition, lights, radio and more. SLIs have a shallow charge cycle (the time it takes to run down the battery and charge it back up) and can only deliver power in short bursts of time (e.g. the amount of time it takes to start your car).

    Lithium-Ion (Li-ion) Batteries

    While incompatible with the majority of vehicles on the road, in recent years, there have been a number of automobiles, including hybrids and electric cars that use Lithium-Ion batteries. Li-ion batteries are able to store significantly more energy and are a fraction of the weight compared to traditional lead-acid batteries. However, one of the major drawbacks of Li-Ion batteries is their short lifespans (the typical Li-ion lasts about three years regardless of use).

    Premium SLI Batteries

    AGM or Absorbent Glass Mat is an advanced lead-acid battery that provides superior power to support the higher electrical demands of today’s vehicles and start-stop applications.

    AGM deep-cycle batteries are extremely resistant to vibration, are totally sealed, non-spillable and maintenance-free. AGM offers better cycling performance, minimal gassing and acid leakage when compared with conventional lead-acid batteries.

    The end result of all of the features of AGM technology is superior life performance.


    In AGM batteries, the positive and negative plates are separated by an absorbent glass mat that absorbs and holds the battery’s acid and prevents it from flowing freely inside the battery. The plates are tightly compressed into each cell and held under pressure in the plastic case. The internal compression limits the shedding of plate material caused by cycling and allows for significantly longer life. The element compression also lowers internal resistance and maximizes pulse power output. A rigid container maintains the necessary compression throughout the battery’s life.

    The basic design also includes relief venting to release pressure from minor gassing that occurs during charging. The valves open at low pressure and close automatically to prevent air from leaking into the battery.

    Challenger application: Bosch Platinum H7/L4/94R; 800 CCA and 960 CA Reserve. (48 month free replacement warranty). Cost- $219.


    Another type of premium battery is the Optima Spiral Cell. It has a higher starting power, a quicker recharge and a longer life expectancy than flat-plate batteries. It is built with a SIX PACK® cell design, a series of individual spiral-wound cells composed of two pure (99.99%) lead plates coated in a precise layer of lead oxide. The unique cell design has an internal structural advantage that helps it hold its shape even under harsh weather conditions, corrosion and heavy vibrations, which traditional batteries are not built to withstand. OPTIMA Batteries are non-spillable, like AGM batteries, and can be mounted in any position. (Note- There is no Challenger application).


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