The battery master switch is a simple but powerful accessory.
It has two main functions:
1) Battery isolation – Used to link or disconnect batteries.
2) Equipment isolation – Used as a main power switch to accessories.
Battery isolation can be done with 3 types of isolators. a) Master Switch. b) Heavy duty solenoid / relay. c) Smart Isolator also known as a VSR (Voltage Sensing Relay) or Electronic Isolator.
Note: Diode Isolators are not recommended as they have a substantial voltage drop and batteries do not fully charge.
Equipment isolation is an important safety issue with high current accessories that are not easily fused like winches and inverters. These accessories are not used all the time and have heavy high current cables connected to them which if shorted out in an accident or simply rub through can cause serious damage or even a fire.
The master switch can be used to prevent battery drain from electronics when a vehicle is stored or shut off battery power in an emergency. It can also prevent vehicle theft and damage from vandals operating your winch from outside the vehicle on vehicles left unattended.