Main functions of a battery switch (engine off):
- Efficiently disconnect the electrical installation from the battery.
- Avoid battery discharge when engine is stopped or when the boat is not used.
- Prevent short-circuits and associated risks of fire.
- Provide safety during maintenance/installation on the electrical installation.
- Protect against theft.
On boats, the auxiliary circuit of battery disconnect switches is typically used to provide the current field to separately excited alternators, thus featuring a protection, should the circuit be accidentally open when the engine is running.