The rate at which a 12V battery discharges can vary depending on several factors. Some of the main factors that affect the discharge rate are:

1. Battery capacity: Every battery has a certain capacity, expressed in ampere-hours (Ah). The larger the capacity of the battery, the longer it will last before it is empty. Therefore, a battery with a higher capacity can last longer than one with a lower capacity.

2. Current usage: The current usage of the connected devices or systems also determines how quickly a battery discharges. The higher the current usage, the faster the battery will deplete. Current consumers such as lighting, heating, air conditioning, audio equipment, and other electronic devices all affect the battery's discharge rate.

3. Usage duration: How long the connected devices or systems are used obviously influences the battery's discharge rate. For instance, if you use high power consumers for an extended period, the battery will run out more quickly than if you use them only briefly.

4. Charge status: A battery that is already partially discharged will deplete faster than a fully charged battery. Therefore, it is important to regularly recharge the battery to maintain optimal capacity.

It is difficult to provide an exact duration in which a 12V battery will discharge, as this depends on the mentioned factors and the specific usage conditions. Generally, you can