Here is a quality 12V DC motion sensor... From backwoodssolar.com
12 VOLT DC MOTION SENSING LIGHT
SWITCH 12 VOLT DC MOTION SENSING LIGHT SWITCH with TIMER
10 year warranty
RAB motion and heat sensing switch is 12 volt DC powered so it can work full time even if your inverter is off or in standby mode. Turns lights
on at approach, and holds for adjustable time, 5 seconds to 12 minutes after motion stops. Sensitivity distance is adjustable, up to about 50 feet out, farther in colder weather with a test LED showing pick-up area.. Connect directly to any 12 volt light, or use a 12 volt relay to switch a 120 volt light. Set for night only operation, or use as security alarm, by setting for day/night operation. Switches 8 amp DC. 7 milliamps idling; 44 milliamps when activated.