Energy of a Truck Battery

We all know someone who has done it before. That is right; I am talking about giving that truck driver, driving alongside of you, the signal to honk his horn. From the average day delivery trucks that double park in front of a store, to the semis that carry shipments of products, trucks run just like a regular automobile, with an engine and diesel in its tank.

Trucks are often categorized into three groups according to weight; pickups and tows would be considered light, delivery and flatbeds would be medium, and garbage trucks and tankers would be considered heavy. Depending on size and usage, trucks can have regular gasoline engines or diesel. Moreover, just as the type of engine varies, so does the battery.

The most important use for the battery is to supply energy to the starter motor and the ignition system. Common ratings for automotive batteries are based on cold cranking amps, CCA, reserve capacity, RC, and amp hours, Ah. CCA is the current delivered for 30 seconds while keeping the battery voltage above 7.2 volts at 0° F. This quick burst of energy is used to start the engine. RC is how long it takes a fully charged battery to discharge 25 amps until the voltage drops below 10.5 volts at 80° F. Ah is how much current a battery will discharge over an hour. Most batteries will use a 20-hour rate.

Generally, small trucks need only one battery. However, as the number of cylinders in the engine increases, the CCA requirement also increases. The large the truck, the larger the engine, the more CCA needed. As semi-trailers fall under the heavy category, they often use several batteries to meet the requirement.

To find the amount of energy in a battery,

E = P·t = V·I·t

Where

E = Energy in joule
P = Power expressed in watts
t = Time expressed in hours
V = Electromotive force expressed in volts
I = Current Expressed in amperes

Which means we multiply the voltage by the Ah rating. However, because it is in hours, we multiply the number by 3600 seconds/hour to get the right SI unit, joules.

Source: Odyssey Batteries | Battery Specifications. West Coast Batteries Inc.

Source: US Battery Specs. US Battery Manufacturing Co.

Source: Battery Product Line Specifications. Caterpillar Inc.

Sze Yin Tam -- 2006