Just installed a new lithium battery and the BMV-712. Been watching some videos on configuring the 712. Most mention setting the Low Voltage Relay. I have one lithium battery. Only have a victron 100/50 solar charger. That's it. Nothing else. Is a relay applicable in my set up? At a very basic level, when would one use a relay? Is it supposed to be used to trigger something in another device? Not sure how it would tell my solar charger to turn off. Thanks!