The interesting question is what happens when the battery dies · review
The only lock here that says what temperature it will still work at — down to minus thirty.
The conclusion The only lock on this shelf that tells you how cold it can get before it stops working — minus thirty Celsius — which in a northern winter is a more useful figure than any IP rating, and BHMA Grade 3 with the 100,000-cycle count behind it. Apple Watch unlocking and a spacer that covers smaller bores are both good details. The failure path is a physical key and nothing else: no emergency terminal, where six locks here have one.
NO emergency power terminal. Nothing about where fingerprint data is stored.
And it is the figure a cold climate needs.
A smart lock is a motor and a battery on the outside of a building, and the cold finds both.
Alkaline AA cells lose a large part of their usable capacity below freezing. A bolt in a swollen or iced frame needs more current, not less. A fingerprint reader can simply stop responding.
Minus thirty degrees Celsius to plus seventy is a serious range, and it is the only one on this shelf — every other lock here gives an IP rating and nothing about temperature.
Which three of the four graded locks here do not give.
BHMA Grade 3 is the residential baseline. eufy publishes the cycle count that earned it.
A hundred thousand operations is about thirteen years at twenty a day.
Which is the minimum the shelf accepts.
This shelf’s introduction: a key override, an emergency terminal that takes a power bank, or nothing at all.
A key always works, needs no charge and cannot fail. What it does not do is help the person at the door with a flat lock and the key in a drawer indoors.
Six locks on this shelf add a USB-C port that lets a power bank open the door.
So the buying tip is not optional here: keep a physical key somewhere that is not inside the locked house.
Which is the detail that saves the installation.
American deadbolt holes are normally 2-1/8 inches, or 54 mm (2.13 in). A 1-1/2 inch bore is common on older and European-style doors, and a lock built for the larger hole will not sit flush on it.
Remove the spacer and the same lock covers both.
Two locks on this shelf name both bore sizes. Most publish neither.
On sale at around $100 on the American Amazon store at the time of checking.
Prices and availability are what Keepa reported on the date this page was updated; both move.
Prices quoted in this text were read on October 8, 2026. The live price is at the top of the page.
| Environment | An operating temperature range of −22 °F to 158 °F (−30 °C to 70 °C), stated, with IP53 weather resistance. It is the ONLY temperature range published on this shelf, and on a front door it is the specification that decides whether the lock works in a hard winter — lithium and alkaline cells both lose capacity in the cold, and a motor driving a bolt through a frozen frame needs the current |
|---|---|
| Grade | BHMA Grade 3 certified after being locked and unlocked more than 100,000 times — stated with the cycle count, which three of the four graded locks on this shelf do not give |
| Failure path | A physical key, one of the six ways to unlock. NO emergency power terminal is published, so there is one layer rather than two — and this shelf's introduction says this is the question that should decide the purchase. Six locks on this shelf publish both a key and a USB-C port |
| Credentials | Six ways: fingerprint reading in under one second, the eufy Security app, the keypad, a physical key, an Apple Watch, and Alexa or Google voice. The Apple Watch is unique on this shelf and is the most practical of the six in the rain |
| Battery | 8 AA cells for around 8 months, stated to vary with how often the lock is used. The variability is acknowledged without a figure, where one lock on this shelf states its assumption as about ten unlocks a day |
| Biometrics | Self-learning fingerprint recognition that becomes more precise with every touch, stated. Nothing is published about where the fingerprint data is stored |
| Connection | Built-in Wi-Fi with no bridge required, stated, and integration with a eufy doorbell for keyless-entry routines within the same app |
| Fitting | Compatible with most standard deadbolts and fits bores under 54 mm (2.13 in) by removing a spacer — stated, with a 15-minute installation and no drilling. The spacer detail is the practical part: a smaller bore does not mean a different lock |
| Security | An alarm triggered by an unusual attempt to open the deadbolt, stated |
| Amazon reference | B0C7C69FPS |
| EAN | 0194644146429 |
Because a smart lock is a motor and a battery on the outside of a building, and both have limits the cold finds. Alkaline AA cells lose a substantial fraction of their usable capacity below freezing; a bolt in a frame that has swollen or iced needs more current, not less; and a touchscreen or fingerprint reader can simply stop responding. Minus thirty degrees Celsius is a serious figure and it is the only one on this shelf — every other lock here publishes an IP rating and nothing about temperature. In a northern winter this is the specification to compare.
It is the minimum this shelf's introduction describes as acceptable, and it is a real answer: a physical key always works, needs no charge and cannot fail. What it does not do is help the person standing at the door with a flat lock and the key in a drawer indoors — and six locks on this shelf add a USB-C port that lets a power bank open the door. This shelf's buying tip is the resolution either way: keep a physical key somewhere that is not inside the locked house. On this lock that advice is not optional.
It lets one lock fit two bore sizes. American deadbolt holes are normally 2-1/8 inches (54 mm) but a 1-1/2 inch (38 mm) bore is common on older and on European-style doors, and a lock built for the larger hole will not sit flush on the smaller one. eufy ships a spacer that comes out for bores under 54 mm (2.13 in), so the same lock covers both — which is the sort of detail that decides whether a fifteen-minute installation is fifteen minutes. Two locks on this shelf name both bore sizes; most publish neither.
Between security devices of the same category and nearby price. Shown: what they all state. A half-filled column says nothing.
| Model | Price | Grade | Failure path | Credentials | Battery |
|---|---|---|---|---|---|
| eufy Security T8506 Smart Lock C220, fingerprint, 6 ways to unlock | $100 | BHMA Grade 3 certified after being locked and unlocked more than 100,000 times — stated with the cycle count, which three of the four graded locks on this shelf do not give | A physical key, one of the six ways to unlock. NO emergency power terminal is published, so there is one layer rather than two — and this shelf's introduction says this is the question that should decide the purchase. Six locks on this shelf publish both a key and a USB-C port | Six ways: fingerprint reading in under one second, the eufy Security app, the keypad, a physical key, an Apple Watch, and Alexa or Google voice. The Apple Watch is unique on this shelf and is the most practical of the six in the rain | 8 AA cells for around 8 months, stated to vary with how often the lock is used. The variability is acknowledged without a figure, where one lock on this shelf states its assumption as about ten unlocks a day |
| Tapo DL110 smart Wi-Fi deadbolt with fingerprint recognition | $109 | NOT PUBLISHED. No BHMA grade and no IP rating appears, where the same maker's cheaper DL100 on this shelf publishes BHMA Grade 3 and IP54. On a lock costing forty-nine dollars more, the omission is conspicuous | Both layers: a built-in USB-C port for recharging, and included backup keys. On a rechargeable lock the port serves double duty — it is the normal charging route and the emergency one, so a power bank at the door will open it | Six ways in: fingerprint, custom keypad passcodes, Wi-Fi from anywhere, close-range Bluetooth, a smart home assistant, and the included backup keys | A full year of continuous operation on a REMOVABLE rechargeable battery — stated, and the longest runtime on this shelf by four months. Removable is the important word: the pack comes off the door and charges indoors over USB-C, so the lock is never dismantled and there are no cells to buy |
| eufy Security T85D2 Smart Lock C34, Apple Home, keyless entry | $80 | Not published. No BHMA grade and no IP rating, where the maker's own C220 on this shelf publishes Grade 3, IP53 and a temperature range | A physical key, and no emergency power terminal published. One layer rather than two, where six locks on this shelf offer both — and this shelf's introduction calls this the question that should decide the purchase | Four ways: the app, the keypad, a physical key, and voice through Alexa or Google Assistant. There is no fingerprint reader, which is the difference from the maker's C220 on this shelf | Up to 8 months on 8 AA cells BASED ON TYPICAL USAGE OF APPROXIMATELY 10 UNLOCKS PER DAY — stated. It is the only battery figure on this shelf with its assumption published, and the assumption is what makes the figure usable: a household of five going in and out all day will see considerably less, and a second home considerably more. Every other eight-month claim here is the same arithmetic with the condition removed |
| Sifely Fingerprint smart door lock with handle and keypad | $80 | Not published. No BHMA grade, no IP rating and no cycle count, where four locks on this shelf publish a grade and five an ingress rating | A physical key, one of the five ways in. No emergency power terminal is published — and with no battery life published either, the key is the only thing standing between the household and a locksmith | Five ways in: fingerprint, keypad, app, FOB or key. The FOB is unusual on this shelf and is the right credential for a cleaner or an elderly relative, since it needs no phone and no code to remember | NOT PUBLISHED. No cell type, no count, no runtime and no statement of whether cells are included — the only lock on this shelf to publish nothing at all about power, on a shelf whose own tag reads: the interesting question is what happens when the battery dies |
Details checked on October 8, 2026.
A cold climate, where a lock that stops working at minus twenty is a real possibility
Amazon reports what buyers took in the month before this page was last checked: at least 2,000.
The figure is a floor, rounded by Amazon, and read through Keepa — it says what buyers picked, not what a maker claims.
Specifications: the manufacturer sheet for home security products and the matching Amazon product page. Prices and availability: Keepa. Every figure on this page names its source.
Matter over Thread · Apple Home Key · rechargeable Li-ion, 6 months stated · no drilling
A retrofit lock with native Matter over Thread, so it joins Apple Home, Google Home and Alexa without a vendor bridge. Aqara states Apple Home Key support, a rechargeable battery quoted at up to six months, and a quiet unlocking mode.
Best for: A household already running Matter or Apple Home, that wants the lock to be part of it rather than another app.
Retrofit · built-in Wi-Fi, no bridge · Matter over Thread · charged at the door · months per charge
Nuki's fifth-generation lock puts Wi-Fi inside the unit, so remote access needs no bridge or hub, and adds Matter alongside Bluetooth. The battery charges at the door with the supplied cable rather than coming off it.
Best for: A household that wants remote access without adding another box to the hallway.
Retrofit · fingerprint, app and Bluetooth · magnetic auto-lock · 6 cells · no drilling
A retrofit lock that mounts over an existing cylinder with no drilling and no cylinder change. Signstek states fingerprint, app and Bluetooth access, magnetic auto-locking, and six batteries; the existing key still works from outside.
Best for: A first smart lock, and particularly a rented apartment where nothing may be altered.
