When battery is fully charged then the cut off system inside the battery does not let the current t pass further more. Thus the current does not flow through battery when it is fully charged.
Battery disconnect switches are designed to cut-off electrical power, help protect against electrical fires and theft when equipment is not in use. They also provide a reliable way to shut down electrical power during maintenance and protect batteries from excessive drain. Installing a battery cut-off switch is usually done either for safety considerations or as an anti-theft precaution.Battery disconnect switches can help preserve battery life and prevent theft or tampering. They work by cutting off the connection between your battery and the accessories that can drain it. Battery disconnect switches prevent constant drain while your vehicle is in storage and can be relatively easy to install.
In electronics, the cut-off voltage is the voltage at which a battery is considered fully discharged, beyond which further discharge could cause harm. Some electronic devices, such as cell phones, will automatically shut down when the cut-off voltage has been reached.The negative cable connects to the body ground already—so there's no additional danger if it rubs. It's the same principle as why you should always disconnect the battery's negative side first before performing electrical service.
A battery disconnect unit (BDU) is arranged to selectively enable current flow between a power source and a battery pack of a vehicle, and between the battery pack and the vehicle.As implied by the name, an RV battery disconnect switch provides you with a simple way to cut off the main RV circuit from your battery. Typically, this switch is located near your battery inside the battery compartment, but it may also be in a nearby maintenance bay.
To find out if this is the case with your rig, get a 12-volt test light, push the switch to Storage, then disconnect the negative terminal on one of the batteries. Touch the probe to the post and the alligator clip to the cable. If the light comes on, you have a draw.