Leisure battery installation and Split Charge circuit.
Part 5 - Putting it all together.
So, we now have a leisure battery, a relay and a bunch of wires. Now we need to put it together.
Consider the diagram below:
When the alternator starts to spin i.e. the engine is running, the thin wire in the diagram becomes live, activating the electro-magnet of the relay and pulling the switch on. This now connects the leisure battery into the charging circuit, and both the batteries start to charge.
When you get to your destination and you stop the vehicle, the alternator is no longer spinning, so the electro magnet in the coil is deactivated and the switch opens, disconnecting the leisure battery from the charging circuit. The other thin wire at the top of the diagram is the positive feed to the fusebox - you can now kick back and switch on all your twelve volt gear safe in the knowledge that even if you flatten your leisure battery, you will still have a full charge in your main battery to start the vehicle and get you home!