Commercial trucks and construction equipment use bigger batteries than cars, and usually more than one. Here is how the three most common heavy-duty sizes compare.
| Size | Approx. case (in) | Duralast Heavy Duty CCA | Typical use |
|---|---|---|---|
| Group 31 | 13.0 × 6.8 × 9.4 | 750 or 950 | Class 8 trucks, buses, tractors, newer equipment |
| 4D | 20.8 × 8.8 × 9.9 | 1,000 | Mid-size equipment, older trucks, buses, marine |
| 8D | 20.8 × 11.0 × 9.9 | 1,400 | Bulldozers, loaders, large diesel equipment |
Battery banks on semi trucks
Most semis start on three or four Group 31 batteries wired in parallel. That keeps the system at 12 volts while multiplying the cranking power and reserve. Because the batteries share the load, a single weak one drags the others down, and one new battery in an old bank wears out early. Replace the bank together.
24-volt equipment
Many bulldozers, excavators and loaders run 24-volt starting systems. They use two 12-volt batteries wired in series, so both batteries must match and should be replaced at the same time.
Choosing cranking amps
Cold cranking amps (CCA) measure how much current a battery can deliver to start an engine in cold conditions. Large diesels need a lot of it. Match or exceed the CCA the truck or machine calls for; the 31-950 suits big engines and hard starting, while the 31-750 suits lighter duty.
Equipment that sits
A machine parked between jobs keeps drawing small amounts of power, and summer heat speeds up self-discharge. Disconnect or maintain batteries on idle equipment, and have them tested before a job starts.
Need batteries on a truck or a job site? See semi truck battery replacement or heavy equipment batteries, or call us.