How Many Batteries Does a Semi-truck Have?

A semi-truck runs on more than just the engine. The battery system is a crucial component that powers all the electronic systems in the truck. This article covers some important aspects of semi-truck batteries, including how many batteries they have, where they are located, and how often they should be checked.


Number of Batteries in an Electric Semi-Truck

The Tesla Semi, a truck that debuted in 2017, is an electric vehicle with advanced battery technology. The specific details of its battery system have not been disclosed by Tesla. Still, it is known that the vehicle uses 4680 battery cells. These cells are lighter and have a higher energy density, potentially reducing the weight of the electric Semi. According to Tesla’s estimates, the electric Semi can travel up to 500 miles on a single charge.

Battery Location in a Semi-Truck

Semi-truck batteries are usually located in the cab, close to the electronic systems that they power. Sometimes, they may also be found in the truck’s bed. Knowing the battery’s location is essential in case of an emergency. If you notice any issues with the battery system, take the truck to a qualified mechanic as soon as possible.

Battery Maintenance for a Semi-Truck

To ensure the battery system is in good working order, check the batteries at least once a month. If you notice any problems, take the truck to a mechanic immediately. Trying to fix battery problems yourself can cause further damage. Mechanics have the tools and experience to diagnose and repair battery issues and recommend the best course of action.

Number of Batteries in a Diesel Truck

Diesel trucks typically have two parallel batteries, providing the necessary power to start the engine and run the accessories. However, starting a diesel truck with only one battery can cause damage to the electrical system. It may need to provide more power to run all the accessories.

Replacing Batteries in a Diesel Truck

It is best to replace both batteries in a diesel truck at the same time. When one battery fails, it causes more stress on the other battery. Replacing both batteries simultaneously will prevent unnecessary stress on the other battery and keep the truck running smoothly.

Group Size of Semi-Truck Batteries

The most common type of battery used in trucks is the BCI Group 31 battery, which comes in three main types: starting, deep cycle, and dual purpose. Starting batteries are for providing a large amount of power for a short time. They are typically used to start the engine. Deep cycle batteries are for providing steady power over a long period and are used for accessories. Dual-purpose batteries provide both starting and deep-cycle power. They are used in applications where both types of power are needed.

Weight of Semi-Truck Battery

The battery that powers an electric semi-truck would weigh around 46,000 pounds, more than half the weight of the entire truck. The cost of an electric semi-truck battery is high, given that the lithium-ion battery in an electric Tesla S car, which weighs 1,200 pounds, costs around $15,000.


The battery system is a vital component of a semi-truck that powers all the electronic systems. Regular battery maintenance, knowing the battery’s location, and using qualified mechanics are crucial to keeping the battery system working correctly. Knowing how many batteries are needed and how they work is also essential in the event of a problem.

About the author, Laurence Perkins

Laurence Perkins is the passionate car enthusiast behind the blog My Auto Machine. With over a decade of experience in the automotive industry, Perkins has knowledge and experience with a wide range of car makes and models. His particular interests lie in performance and modification, and his blog covers these topics in-depth. In addition to his own blog, Perkins is a respected voice in the automotive community and writes for various automotive publications. His insights and opinions on cars are highly sought-after.