You do not have to have a switch on the ignition. When ever you turn the main unit off the ignition will be shut off. It acts like a failsafe switch and will draw about 2mAH per DAY from your battery. The main unit will draw about 5mAH per DAY from your battery if you use the failafe switch. Its safe to keep your batteries hooked up under these conditions for a couple months. The Ignition Cutoff fiber-optic receiver (that goes on your ignition) has a charge lead you can use with a charge jack (like an Ernst) to check and charge your ignition battery.