The Physics
An encyclopedia of scientific essays

Energy of a Truck Battery

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Bibliographic Entry Result
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Battery FAQ. Northern Arizona Wind & Sun. May 16, 2006
Group Amp hours Voltage
Group 31 95–125 Amp hours 12 Volts
4-D 180–215 Amp hours 12 Volts
8-D 225–255 Amp hours 12 Volts
4.10–11.02 MJ
Sick, Friedrich & Erge, Thomas. Photovoltaics in Buildings: A Handbook for Architects and Engineers. 1 June 1996: 37 "They can be sold as single cells or more commonly as a series combination of six cells to form a 12 V battery …. Small PV systems, up to about 120 Ah, mainly use modified car or truck batteries." 5.18 MJ
United States Congress, House Committee on Military Affairs. Army Appropriation Bill, 1919. 1918: 584 "Furnish and install on the truck a 6-volt 120-ampere hour battery of best make, designed for lighting and ignition purposes only." 2.59 MJ
Odyssey Batteries | Battery Specifications. West Coast Batteries Inc. May 16, 2006 [see table 1 below] 1.90–4.32 MJ
US Battery Specs. US Battery Manufacturing Co. May 16, 2006 [see table 2 below] 1.8–7.2 MJ
Battery Product Line Specifications [pdf]. Caterpillar Inc. May 31, 2006 [see table 3 below] 1.38–8.2 MJ

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


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.

Table 1
Battery Model General Battery Description
PC 1200T Low temperature auto/truck engine start, no metal jacket, SAE term
PC 1200MJT Auto/truck engine start, W/metal jacket, SAE Terminals
PC 1200LMJT Auto/truck engine start, W/metal jacket, left positive terminal, SAE Terminals
PC 1700T Super heavy duty truck engine start, low temperature, no metal jacket, SAE Terminals
PC 1700MJT Super heavy duty truck engine start, W/metal jacket, SAE Terminals
PC 2150S Group 31 truck, marine, 3/8" stud terminals
Model Voltage Nominal Capacity
(20 Hr Rate-Ah)
PC1200 12 44
PC1700 12 68
PC2150 12 100

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

Table 2
US Battery Model Minutes @ 25 amps
3EE 100
3ET 140
8D 290
8D 400
16TF 250
17TF 150

Source: US Battery Specs. US Battery Manufacturing Co.

Table 3
Wet Batteries
BCI Group Size Part No. Volts Amp Hr. Capacity @ 20 Hrs.
1 8C-3617 6 100
2 8C-3629 6 90
3EE 8C-3620 12 54
3EH 8C-3632 6 115
4 8C-3633 6 125
4D 8C-3623 12 115
4DLT 8C-3622 12 100
7D 8C-3635 6 156
8D 8C-3624 12 190
24F 3T-5858 12 55
27 8C-3601 12 65
27F 8C-3602 12 65
30H 8C-3627 12 100
Dry Batteries
BCI Group Size Part No. Volts Amp Hr. Capacity @ 20 Hrs.
1 8T-9734 6 100
3D 8T-9730 6 320
7D 8T-9731 12 156
24F 9X-1382 12 50
26 145-4517 12 48
26R 145-4518 12 48
27 3E-8925 12 55

Source: Battery Product Line Specifications. Caterpillar Inc.

Sze Yin Tam -- 2006