Batteries on heavy-duty vehicles may seem like complicated components that are difficult to understand, let alone maintain. Truck Parts & Service spoke to some experts and did extensive research to learn the basics of batteries-what they are, how they operate and how they’re maintained.
According to the textbook, Today’s Technician: Medium- and Heavy-Duty Truck Electricity And Electronics, a battery is an electrochemical device that produces electrical energy by a chemical reaction that occurs between two dissimilar materials, or plates.
“These plates are immersed in an electrolyte solution, and when a connection is made between the positive and negative potential of the battery, the energy is released. The battery’s energy in chemical form is released as electrical energy when a load is placed between the negative and positive potential of the battery,” the book explained.
One function of the battery is to stabilize the voltage. The battery provides a reference around which the alternator and regulator control system voltage. Without a battery voltage reference, the alternator can output voltages beyond the safe limit of the truck’s electrical components, according to the book.
If the charging system of the truck fails, the battery has to supply the current that is necessary to keep the truck running for a specific time period. Most batteries will supply 25 amperes to maintain a minimal working voltage for approximately 120 minutes.
When the vehicle is off, there still will be a draw on the battery because of the onboard electronic devices that need to stay on while the ignition is off.
Many components rely on the battery, therefore it must be kept in good condition. Defective batteries can shorten starter life or alternator life, damage properly functioning batteries and internal engine components and may generate expensive road service bills. Today’s Technician: Medium- and Heavy-Duty Truck Electricity And Electronics listed the following functions that show the importance of a properly functioning battery in the electrical system of a truck.
- It provides a source of current for the starter, fuel solenoid and injectors and any other electrical device needed to start the engine.
- It must be able to supply, for a limited amount of time, power to electrical devices when the engine is not running or the electrical load used will exceed the output of the generator.
- It acts as a stabilizer of voltage for the truck’s electrical system.
- It must be able to store energy over extended periods of time.
All batteries have two terminals to allow connection to the truck’s electrical system: A positive terminal and a negative terminal. The following are the most common types of terminals, according to the book.
- Post terminals: Round, tapered terminals found on top of the battery, the positive post is larger in diameter than the negative post. This helps to identify the polarity of the battery post and prevent connecting the battery in reverse polarity.
- Side terminals: Internal threaded post positioned in the side of the battery case, which require a special bolt to connect the cables.
- Top stud terminals: Threaded terminals are on top of the battery, and they are the most popular for heavy-duty trucks. They have tangs that resist rotation of the cable when tightened properly with the proper cable terminal end. This style of post makes it easy to stack more than one cable on the terminal.
It’s important that battery terminal connections be kept clean and tight, but never overtighten terminal connections, and refer to the manufacturer’s specifications for the proper torque setting.
Always make sure to wire brush both the terminal and connector to a tarnish-free condition before attaching cables to the battery. A baking soda solution should be used to wash away any buildup of corrosion that may have occurred, according to the Technology & Maintenance Council (TMC).
Corrosion forms on the exposed metal areas of terminal connections from exposure to air, moisture and traces of electrolytes that contact them.
If the terminal connectors are not designed to seal the connection from the atmosphere, it will be necessary to disassemble and clean the terminals periodically to prevent high-resistance connections from developing, according to TMC.
After cleaning and reassembling the cables, application of light grade or other commercial preparations will retard the formation of new corrosion. The time between cleanings will vary from application to application, so you may want to clean the cables during an oil change.
In order to ensure maximum battery life, adhere to the following procedures from TMC.
- Ensure all the original equipment and replacement batteries meet TMC Recommended Practice 125.
- Keep battery boxes clean and make sure all hold downs are secure.
- Follow all the battery manufacturer’s recommendations concerning battery charging, testing and handling procedures.
- Make sure to follow the battery manufacturer’s storage recommendations.
- Adhere to TMC Recommended Practice 121 on Auxiliary Start Procedures.
- Contact the OEM and ask about the available battery box options. Use an installation that mounts the batteries with their long axes parallel, and close in to the frame whenever practical.
According to TMC, cold cranking ampere (CCA) is the current that a battery can supply at 0
