The main difference between a starter battery and a regular battery, such as a semi-traction battery, lies in their design and the function they fulfill. Here are the main differences:

1. Design: A starter battery, also known as an SLI (Start-Lighting-Ignition) battery, is designed to deliver short, intense bursts of power to start a vehicle. Starter batteries have thin and shallow plates, resulting in a large surface area and quick power release. On the other hand, regular batteries, like semi-traction batteries, are designed to provide prolonged power over a longer period, often at a deeper discharge.

2. Power Output: Starter batteries are optimized for delivering high power output over a short period, which is necessary to crank the starter motor of a vehicle. Regular batteries, such as semi-traction batteries, are capable of providing a more consistent power output over an extended period.

3. Capacity: Starter batteries generally have a lower total capacity than regular batteries. This is because they are primarily designed to deliver short, intense bursts of power when starting a vehicle. Regular batteries often have a larger capacity, meaning they can store more energy and deliver power over a longer period.

4. Deep Discharge: Regular batteries, like semi-traction batteries, are better suited to withstand deep discharges and repeated recharging, while starter batteries are not designed to be regularly deeply discharged. Deep discharge can significantly shorten the lifespan of a starter battery.

It is important to choose the right type of battery based on the application. Starter batteries are ideal for vehicles where short, intense power bursts are required, such as cars, motorcycles, and boats with starter motors. Regular batteries, like semi-traction batteries, are more suitable for applications where a long-lasting power source is needed, such as maritime applications, recreational vehicles, caravans, solar energy systems, and electric vehicles.