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SvWhy separate the batteries?
How a battery isolator relay works
If you want to be sure that you can always start the engine, the starter battery should be automatically separated from the consumer batteries when the engine is switched off.
The simplest and cheapest way to achieve this is to use a battery isolator relay.
A battery isolator relay works like a remote-controlled switch and is connected to the ignition key. When you turn the ignition key to start the engine, the relay engages and connects the starter and auxiliary batteries so that both are charged.
When you switch off the engine, the isolator relay disengages so that your consumers cannot drain the starter battery. This ensures that you can always be confident of having power in your starter battery when you need to start the engine.
How to install your battery isolator relay, you can read about here
