The lifespan of a semi-traction battery can vary depending on several factors, such as the brand and quality of the battery, usage, maintenance procedures, and environmental conditions. Generally, a well-maintained semi-traction battery can have an average lifespan of 3 to 5 years, but this can be longer or shorter depending on the circumstances.

Semi-traction batteries are designed for cyclical use, which means they can be repeatedly discharged and recharged. They are often used in applications such as boats, caravans, golf carts, electric wheelchairs, and campers. These batteries can be regularly discharged and then recharged without harming their lifespan.

To maximize the lifespan of a semi-traction battery, there are some important maintenance guidelines to follow:

1. Regularly charge the battery: It is important to regularly charge the battery, even when it is not in use. This helps to keep the battery in good condition and prevents deep discharge.

2. Avoid complete discharge: Try to avoid fully discharging the battery. Deep discharge can negatively impact the battery's lifespan. Charge the battery before it becomes too discharged.

3. Check the electrolyte level: If the semi-traction battery has maintenance openings, regularly check the electrolyte level (if applicable) and top it up with distilled water if necessary. Ensure the battery always has sufficient electrolyte to function properly.

4. Clean the battery terminals: Keep the battery terminals clean and free of corrosion. Remove any corrosion with a mixture of water and baking soda and carefully brush the terminals clean.

It is important to note that the actual lifespan of a semi-traction battery can vary greatly depending on specific conditions and its usage. Following the manufacturer's recommendations and carefully maintaining the battery can help to extend its lifespan.