The August arrived the way every unit does on this bench: bought at retail, $229, same listing you'd click. It went on over our lab door's existing deadbolt with a screwdriver and nothing else — twelve minutes, and the outside of the door didn't change at all. That's the entire pitch, and pitches are cheap. So we spent three months finding out whether "the fastest smart lock we've timed" survives contact with actual mornings: groceries, a dead phone battery, a dog pulling toward the yard.
Retrofit locks live or die on one number: does it actually open before you reach for it, or does "auto-unlock" become a party trick you disable in week two out of frustration. So that's where we started, with an instrument instead of an opinion.
How we tested this one
- Bought at retail for $229 — no loaner units, ever
- 100 timed approach-to-open attempts, varied speed and angle
- 12-minute install, timed with one person and a screwdriver
- 3-month battery drain logged under daily real-world use
- Pick & bump test inherited from the underlying deadbolt cylinder
- Loaned to a renter household for three weeks — real doors, real routines
The 100-approach bench, and the 3 it missed
Auto-unlock is the feature every retrofit lock promises and the one most quietly fail at — either it's too slow to trust, or it's trigger-happy enough to open for the wrong signal. We ran 100 approaches at three speeds (walking, jogging, "just got out of the car with bags") and three angles to the door. The August succeeded 97 times, with a mean time from approach to open of 0.9 seconds — the fastest we've timed on any lock, retrofit or replacement. The three misses all shared a cause: a phone left in a bag rather than a pocket, which delays the Bluetooth handshake by roughly two seconds. That's a real failure mode, not a rounded-away one.
Twelve minutes, and your key still works
We timed the install with a single installer and a Phillips screwdriver: unscrew the interior deadbolt knob, mount the August's motor over the existing tailpiece, pair the app, done — 12 minutes on our lab door, matched within a minute across two more doors in a renter household we loaned a unit to for three weeks. The exterior of the door is untouched. Your original key still opens the deadbolt manually, which matters more than it sounds: a firmware issue, a dead battery, or a landlord inspection all resolve the same way they did before you installed anything.
One quirk from the three-week loan: on a single humid night, the renter's phone Bluetooth briefly failed to auto-unlock and the app showed a stale 'connecting' state for about 40 seconds before catching up. A firmware update issued during our test window addressed the underlying reconnect delay; we haven't reproduced it since. Worth knowing, didn't move the score.
3 months — the tax for staying inside your existing lock
Battery life is where the retrofit design pays a real cost. Four AA batteries lasted 3 months under our daily-use profile (roughly 8 unlocks a day, Bluetooth and Wi-Fi bridge both active) — the shortest of any lock on our current bench, and about a third of the Yale Assure Lock 3's measured 9 months. The August's own app gives a two-week low-battery warning with a chirp, which we verified fires reliably; we never got caught fully dead in three months of testing. But budget for it: this is a lock you will change batteries in four times a year, not once.
The security ceiling is worth being direct about too: because the August clips over your existing deadbolt rather than replacing it, its pick-and-bump resistance is inherited entirely from whatever cylinder was already on your door — in our case, a Grade 2 unit, so "N/A, keeps your cylinder" on our own registry isn't a dodge, it's the honest answer. If your existing deadbolt is old or low-grade, the August doesn't upgrade that; it automates it.
The score weighting here favors speed, install simplicity, and not touching your existing hardware — 30% unlock performance, 25% install & compatibility, 20% battery & reliability, 15% security ceiling, 10% smart-home ecosystem. Sort for renters specifically and the August jumps to 9.4; sort for pure battery life and it drops to 7.6, behind the Yale. Both are the same data, different lenses.
The honest summary: it's the fastest, simplest, least invasive smart lock we've put on a door, and the batteries and the keypad-as-add-on are the two real costs of that simplicity. For a renter, or anyone who doesn't want to think about their door hardware ever again, nothing we've tested beats it. For a homeowner who wants a keypad and can live without the original key, the Yale is the more complete answer — we say so directly in the full comparison.