How far does the motion sensor detect movement, and what is the detection area?

The motion sensor detects movement up to 30 feet away and covers up to a 120-degree field of view, with adjustable motion detection sensitivity.

How bright is the Ring Smart Lighting Spotlight Battery, and can the brightness be adjusted?

It provides up to 400 lumens of brightness, and the LED brightness is adjustable to match the space you're lighting.

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Ring Smart Lighting Spotlight Battery - 400 Lumen Adjustable LED, Motion-Activated, Weather Resistant, Black

UP TO 400 LUMENS OF ADJUSTABLE BRIGHTNESS: A bright, 3500K LED spotlight illuminates garages, sheds, porches, and dark corners of the yard, with adjustable brightness to match the space you're lighting.
MOTION-ACTIVATED WITH ADJUSTABLE DETECTION: Detects motion up to 30 feet away across a 120-degree field of view, with adjustable sensitivity and an auto-shutoff timer (30 seconds to 2 minutes) so the light turns off when it's no longer needed.
CONNECTS VIA AMAZON SIDEWALK FOR SMART CONTROLS: Link the Spotlight to the Ring app over Amazon Sidewalk to unlock customizable smart controls, schedules, and combinations with other Ring smart lights, doorbells, and cameras; a compatible Sidewalk hub like Ring Bridge (2nd Gen) or Alarm Pro Base Station enables full smart security features where Sidewalk coverage isn't already available.
WORKS WITH ALEXA & CONNECTED DEVICES: Say 'Alexa, turn on the lights' to control the Spotlight through select Alexa-enabled devices, and link it to Ring doorbells and cameras so one triggered light can activate your other connected security devices.
WEATHER-RESISTANT, BATTERY-POWERED DESIGN: Rated IP66 and powered by 4 D-cell batteries (not included) for up to 1 year of use under normal conditions, the Spotlight installs in 5 to 10 minutes with no wiring required.