Yes, you need a battery isolator if you’re running dual battery systems, especially in 4WDs, caravans, or off-grid setups. A battery isolator ensures that your starter battery is protected from being drained by your auxiliary battery, which powers accessories like fridges, lights, or other 12V appliances. It automatically disconnects the batteries when the engine is off, so you don’t get stranded with a flat starter battery. It's a must-have for anyone who relies on multiple batteries to keep their adventures running smoothly.