A semi-traction battery, also known as a deep-cycle battery, is designed to be repeatedly deeply discharged and recharged. Unlike starter batteries that are primarily intended to deliver short bursts of power, semi-traction batteries can handle a significant discharge.

The maximum depth of discharge of a semi-traction battery varies depending on the specific brand, model, and technical specifications of the battery. Generally speaking, semi-traction batteries are discharged to about 50-80% of their total capacity.

It is important to prevent a semi-traction battery from being fully discharged, as this can affect the battery's lifespan and performance. Regularly fully discharging the battery can reduce its capacity and damage the battery.

To optimize the lifespan of a semi-traction battery, it is often recommended to discharge the battery to about 50-80% of its capacity and then recharge it. By not fully discharging the battery, it maintains a good condition and can perform better and have a longer lifespan.

Always consult the instructions and recommendations of the semi-traction battery manufacturer for specific information about the maximum depth of discharge and use of the battery.