Most of the homes in Wills Creek are equipped with the BRK First Alert Model 7010A . These units have no battery backup and have been known to fail and will need to be replaced when this happens. Most of the smoke detectors currently installed are good for 10 years. You can check the expiry date which is located on a sticker on the side of the detector. If it was installed around the same time as Phase 1, it will expire in 2019. Suggested BRK replacement units (noted in the attached picture) do not require any wiring changes, just the mounting bracket which comes with the new unit. These units are battery backup and come with batteries installed. Replacing units is very simple and can be replaced in less than 5 minutes. For more details on smoke detectors and when to change batteries, see below.
www-fire-ca-gov1

By Tom