When tying into constant hot or always powered wiring an illuminated rocker switch placed in the power cord and power source line will prevent battery drain caused by the transmitter constantly trying to send to the unplugged receiver. Been there, done that. Also, a tech advisor with lots experience with wireless backup cameras told me to go directly to the house battery for consistent uninterrupted power to prevent repeated power on off of transmitter as they can be extremely sensitive to fluctuations causing repeated connecting/disconnecting and random backup view. Been there done that too. Just my recent personal experience.