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Truck and bus batteries face heavier demands than passenger car batteries: large-displacement diesel engines to crank, auxiliary loads such as tail lifts, refrigeration controls and cabin equipment, constant vibration and, in many export markets, high ambient temperatures. Selecting the right battery is about more than matching the ampere-hour figure. This guide covers system voltage, size standards, performance criteria and supply considerations for fleet and distributor buyers.
System voltage and battery configuration
Most medium and heavy trucks, and many light trucks, use a 24 V electrical system. Some light trucks and most pickups use 12 V. The voltage depends on vehicle model and market specification.
| Configuration | Wiring | Result |
|---|---|---|
| Two 12 V batteries in series | Positive of one to negative of the other | 24 V, capacity of one battery |
| Two 12 V batteries in parallel | Positive to positive, negative to negative | 12 V, combined capacity |
| Series-parallel (four batteries) | Two series pairs connected in parallel | 24 V, double the capacity of one series pair |
Rules for batteries in the same bank:
- Use the same model, capacity and technology.
- Replace them as a set. Pairing a new battery with an old one causes the weaker battery to be overcharged or over-discharged, shortening the life of both.
- Keep cable and connection resistance equal, and clean and tighten all terminals.
Size standards for trucks
| Family | Common truck and bus sizes | Typical vehicle origin |
|---|---|---|
| JIS | Large F, G and H case sizes, for example 115F51, 145G51 or 190H52 | Japanese trucks and buses |
| N-series | N100, N120, N150, N200 | Asian-built trucks and buses, widely used in Africa and the Middle East |
| DIN/EN heavy duty | Commercial vehicle cases in capacities such as 140 Ah, 180 Ah and 225 Ah | European trucks and buses |
| BCI | Group 31 and others | North American trucks |
The performance rank in a JIS code and the capacity in an N-series designation vary between manufacturers for the same case size. Read the full specification rather than choosing by code alone. For a detailed explanation of codes, see how automotive battery sizes work.
Terminals
Truck batteries use several terminal types:
- Taper posts (JIS or SAE/DIN pattern), common on JIS, N-series and DIN batteries
- Threaded stud terminals, found on some BCI Group 31 batteries
- Combination terminals carrying both a post and a stud on some commercial designs
Check that the terminal type suits the vehicle's cable ends and that the layout suits cable routing.
Performance criteria
Cold cranking amps
Cold cranking current indicates the ability to start an engine under cold conditions. Even in hot climates it is a useful measure of starting strength, particularly for large engines, worn starters and vehicles with high-resistance cabling. Compare values tested under the same standard (JIS, EN or SAE).
Capacity and reserve capacity
Capacity (Ah, typically at a 20-hour rate) and reserve capacity (minutes of supply at a defined load) indicate how well the battery supports electrical loads with the engine off, for example lights, radios, tail lifts and cabin equipment during stops.
Cycling and vibration resistance
Trucks with frequent stops, auxiliary loads or long idling periods cycle their batteries more than a car. Vehicles running on unpaved roads or in construction service need batteries with robust internal construction and a secure hold-down. Some manufacturers offer heavy-duty or vibration-resistant designs for these applications.
Technology choice
| Technology | Truck application notes |
|---|---|
| Conventional flooded, maintenance-free | Most common; sealed-lid design reduces water loss |
| Low-maintenance or hybrid alloy | Allows electrolyte top-up; preferred by some operators in hot climates with regular maintenance |
| EFB | Higher cycling capability for demanding duty and start-stop commercial vehicles |
| AGM | High cycling and vibration resistance; used where specified, including some vehicles with heavy auxiliary loads |
In hot climates, high temperatures accelerate grid corrosion and water loss. Fleet operators with workshop maintenance programs sometimes prefer batteries that allow electrolyte inspection and top-up. Where maintenance is irregular, maintenance-free designs are safer. For technology differences, see EFB vs AGM batteries.
Filled or dry-charged supply
Batteries can be supplied either filled with electrolyte and charged, or dry-charged, with the plates pre-charged and electrolyte added at the destination.
| Filled (wet) | Dry-charged | |
|---|---|---|
| Transport classification | Dangerous goods (for example UN2794, batteries, wet, filled with acid) unless the specific battery qualifies for an exemption | Batteries without electrolyte are generally not regulated as dangerous goods; acid shipped separately is regulated |
| Shelf life | Self-discharges; requires stock rotation and periodic recharge | Long shelf life while sealed |
| Destination handling | Ready to fit after a voltage check | Requires acid filling, a settling period and an initial charge |
| Suitable for | Markets with fast turnover and good distribution | Long transit, slow turnover, or where DG shipping is restricted |
Classification and exemptions depend on battery design and the current transport regulations. Confirm with your freight forwarder before booking. Container planning for batteries alongside other parts is covered in how to order mixed auto parts containers from Thailand.
Checking the charging system
A new battery does not fix a faulty charging system. When fleets report repeated battery failures, check alternator output, voltage regulator operation, belt tension, ground straps and parasitic drain before changing battery brand. Replacement alternators and starter motors must match the system voltage.
Selection checklist
| Check | Detail |
|---|---|
| System voltage | 12 V or 24 V |
| Number of batteries and wiring | Series, parallel or series-parallel |
| Size code and dimensions | Fits tray and hold-down |
| Terminal type and layout | Matches cables |
| Cold cranking current and standard | Meets or exceeds original |
| Capacity and reserve capacity | Suits auxiliary loads |
| Technology | Matches or exceeds original |
| Supply condition | Filled or dry-charged |
Ordering
Browse truck and bus batteries and the truck parts hub for model-specific pages such as the Hino 500. For fleet or distributor battery programs, upload a list with size codes, quantities, technology and supply condition.