The answer — one pick, priced
Get the
First Alert SC5 Battery
$20 under your budget
Google's official Nest Protect successor and the only alarm that interconnects with legacy Nest Protect over Nest Weave — 11 sources, one irreplaceable feature.
Fit ledger — need → measured evidence
■ The catch — co-equal billing, always
Its 2026 reliability record is the worst on this card. Owner reports across Home Depot, Best Buy and the Google Nest community log ~45-second notification latency, false alarms with no smoke present, and complete unit failures — including a CPSC incident report filed by a Deputy Fire Chief in February 2026. No recall has been issued and no firmware fix has been announced.
Dealbreaker? Buy it only for Nest Weave — otherwise Runner-up №1 at $75 ↓
■ Every product has a catch. Verdicts that hide it are how bad buys happen.
Don't buy this if…
- you want basic non-smart smoke detectors without app connectivity
- you need commercial or industrial-grade fire detection systems
- you only need a CO detector without smoke detection
- you need whole-home professional fire monitoring with central station response
Wrong product for you is still a bad buy. These are the cases where we'd send you somewhere else.
Runners-up — if your needs differ
Adjacent verdicts — other needs, same method
Different budget, different household, different job — each of these is already researched, priced and verified. Take the one that matches your need.
Traps — this verdict avoids
Why the First Alert SC5 Battery is right for you
It avoids every trap below — and for family of 4, under $150, it is the pick because it delivers:
The 10-year clock already started
A smoke alarm expires 10 years from the date of manufacture printed on the back — not from the day you installed it, so a unit that sat in a warehouse for two years gives you eight. CO sensors degrade on a 7-10 year clock whether or not they ever see gas.
An app alert is not interconnection
Only a hardwired third wire or a proprietary RF mesh makes every alarm in the house sound together. Wi-Fi and Matter push alerts reach your phone while the alarm outside your bedroom stays silent — and cross-brand interconnection does not exist at all.
Nest Protect is gone
Google discontinued the Nest Protect in March 2025. Existing units keep working to their 10-year expiry but cannot be bought new, and the First Alert SC5 is the official Google-partnered replacement — anything else you see listed is old stock or a reseller.
Provenance — 11 sources, dated
Winners are picked from the full research dossier at knowledgelib.io. Prices, stock and listings are re-verified monthly.