Onelink Smoke alarms

I got these from a neighbor today, I want to wire them up and mess around with them, what would be the best way to power them?

It all depends on what power source they were made in mind with: are they battery, AC + battery, or 10-year battery?

After checking the back they appear to be AC only

That might mean they’re 10-year battery units since AC-only units stopped being made at least a decade ago. What’s the model number? (should have asked this right from the start as a unit’s model number will identify it very quickly & easily)

What are their models? As the first alert onelink series is quite extensive, Some of the alarms are wireless interconnect, some are hardwired/wireless.

The series may be extensive but as long as a unit has “OneLink” somewhere in the name that should mean it’s wireless regardless of power source (that or “Wireless” of course).

Well the onlink series includes a bridge unit (hardwired/wireless), Wireless only, smart wireless only, smart wireless/ hardwired and smart with a Bluetooth speaker. You also have to be careful as to how you wire them. There is a live, neutral and hardwired connect

Yeah, but regardless most OneLink or wireless BRK/First Alert should hopefully work with one another.

Yeah: that’s obvious to anyone who’s wired one (though not all detectors, particularly older ones, have an interconnect wire).