Best Smart Locks with Emergency Power Options
A smart lock is only as reliable as its backup plan, and a dead battery at the wrong moment can leave you locked out of your own home. The models below all include a genuine emergency power method, whether that is a 9V battery terminal, USB-C jump start, or a physical key override, so you are never stranded.
Quick answer
The Schlage Encode Plus is the best overall pick for most US homes thanks to its 9V battery jump terminals, built-in Wi-Fi, and Apple Home Key support.
Why trust ToolBuyerHub
- Cross-checked manufacturer-published specifications before writing any recommendation
- Verified US market availability and configuration for every model discussed
- Owner-feedback themes are summarized as feedback, never presented as our own hands-on testing
- No invented star ratings; see the visible Research Score criteria on this page
- Checked specifications against manufacturer documentation before publishing
- Every lock listed here was checked for a real, manufacturer-documented emergency power or override method, not just a low-battery warning.
Research updated September 2026.
What Matters Most for This Category
The most important factor is which emergency method fits your habits. A 9V battery terminal is the simplest because 9V batteries are cheap and available everywhere, while USB-C jump start is convenient if you already carry a power bank. A physical key override adds a mechanical fallback but means carrying a key, which defeats part of the point of a smart lock. Also check whether the lock needs a hub for remote features, since Wi-Fi built in costs more but removes an extra device.
| Model | Best for | Key specs | Research Score |
|---|---|---|---|
| Schlage Encode Plus Smart WiFi Deadbolt | Best Overall | 9V battery terminals on exterior, Built-in Wi-Fi, Bluetooth, Thread | 94/100 |
| Yale Assure Lock 2 with Wi-Fi | Best Value | 9V battery terminals, Wi-Fi (module included on Wi-Fi model) | 91/100 |
| August Wi-Fi Smart Lock (4th Gen) | Best for Renters | 9V battery terminals, Built-in Wi-Fi, Bluetooth | 89/100 |
| Kwikset Halo Touch Wi-Fi Smart Lock | Best Fingerprint Option | 9V battery terminals, Built-in Wi-Fi | 88/100 |
| Ultraloq U-Bolt Pro WiFi Smart Lock | Best Budget | 9V battery terminals, Wi-Fi (built-in on Pro WiFi) | 86/100 |
| Level Lock+ with Apple Home Key | Best Hidden Design | 9V battery terminals, Bluetooth, Thread, Apple Home Key | 85/100 |
| Bosma Aegis Smart Door Lock | Best for Existing Deadbolts | 9V battery terminals, Wi-Fi (Aegis WiFi model) | 83/100 |
Schlage Encode Plus Smart WiFi Deadbolt
Best OverallPros
- Built-in Wi-Fi means no separate hub
- Apple Home Key and Schlage keypad both work
- 9V jump terminals are clearly marked on the outside
Cons
- Premium price versus basic keypad locks
- Bulkier interior housing than some rivals
Schlage's flagship deadbolt pairs built-in Wi-Fi with Apple Home Key, so iPhone and Apple Watch users can tap to unlock. If the AA batteries die, two 9V terminals on the exterior let you jump the lock for a one-time entry. Based on manufacturer specifications, it carries an ANSI/BHMA Grade 1 rating, the highest residential grade.
Yale Assure Lock 2 with Wi-Fi
Best ValuePros
- Slim, modern interior design
- Wi-Fi model removes the need for a plug-in hub
- Optional keyed cylinder version adds a physical backup
Cons
- Wi-Fi version costs more than the Bluetooth-only model
- Some features need the Yale Access app
The Assure Lock 2 is one of the slimmest smart deadbolts sold in the US, and the Wi-Fi version includes the module in the box. A 9V battery terminal on the exterior provides emergency power, and Yale offers both keyed and key-free versions. Based on manufacturer specifications, it supports Alexa, Google Home, and Apple Home when paired correctly.
August Wi-Fi Smart Lock (4th Gen)
Best for RentersPros
- Installs over your existing deadbolt interior
- No need to replace the exterior hardware
- Auto-unlock works well with phone geofencing
Cons
- Requires a compatible existing single-cylinder deadbolt
- No keypad unless you buy the separate August Keypad
August's fourth-generation lock replaces only the interior thumb turn, leaving your existing keys and exterior trim in place, which makes it a good fit for renters. A 9V terminal on the exterior handles emergency power. Based on manufacturer specifications, it uses CR123 batteries and supports Alexa, Google Home, and Apple Home.
Kwikset Halo Touch Wi-Fi Smart Lock
Fingerprint PickPros
- Fingerprint reader avoids typing a code
- Built-in Wi-Fi needs no hub
- Backlit keypad for night entry
Cons
- Fingerprint readers can struggle with very dry skin
- App experience gets mixed owner feedback
The Halo Touch adds a fingerprint reader to Kwikset's Wi-Fi deadbolt line, so you can unlock with a touch instead of a code. A 9V battery terminal on the exterior provides emergency power if the AAs run down. Based on manufacturer specifications, it fits standard US door prep and supports Alexa and Google Home.
Ultraloq U-Bolt Pro WiFi Smart Lock
Budget PickPros
- Multiple unlock methods including a physical key
- Built-in Wi-Fi on the Pro WiFi model
- Competitive price for the feature set
Cons
- Build feels less premium than Schlage or Yale
- App and firmware updates get mixed owner feedback
Ultraloq's U-Bolt Pro WiFi packs fingerprint, keypad, app, and key access into a lower-priced deadbolt. A 9V battery terminal on the exterior handles emergency power. Based on manufacturer specifications, it fits standard US deadbolt prep and supports Alexa and Google Home.
Level Lock+ with Apple Home Key
Design PickPros
- Fully hidden inside the door, no visible tech
- Apple Home Key tap to unlock
- Includes a physical key override
Cons
- No keypad, so guests need the app or a key
- Higher price for fewer on-device controls
Level Lock+ hides all the electronics inside the door, so the exterior looks like a standard deadbolt. It includes a physical key and a 9V emergency terminal for backup power. Based on manufacturer specifications, it supports Apple Home Key and Thread, and it is sold in both keyed and key-free versions.
Bosma Aegis Smart Door Lock
Retrofit PickPros
- Retrofits over most existing deadbolt interiors
- Keeps your current exterior key and trim
- Lower entry price than full replacements
Cons
- Compatibility depends on your existing deadbolt brand
- No keypad on the base model
The Bosma Aegis replaces the interior half of a compatible deadbolt, similar in concept to August but at a lower price. A 9V terminal on the exterior provides emergency power. Based on manufacturer specifications, it supports Alexa and Google Home and works with many standard US deadbolt brands.
Who Should Avoid the Top Pick
Skip any smart lock that relies only on a low-battery warning with no physical or battery jump method, because a warning does not help once the batteries are fully dead. Also avoid models that require a proprietary hub for basic remote access unless you are comfortable adding another device and app to your setup.
Before You Buy
Measure your door's backset and cross bore before ordering, since most US deadbolts use standard dimensions but older doors can vary. Confirm whether you want a full replacement or a retrofit that keeps your existing exterior hardware, and check whether the lock needs a hub for the features you care about. Finally, decide which emergency method you will actually use, because a 9V terminal only helps if you keep a spare 9V battery somewhere accessible.
FAQs
How does emergency power work on a smart lock?
Most locks with this feature have two metal terminals on the exterior that accept a 9V battery. Touching the battery to the terminals briefly powers the lock so you can enter a code and get inside, then you replace the internal batteries.
Do all smart locks have a 9V emergency terminal?
No. Many budget or older models only offer a low-battery warning or a physical key override. If emergency power matters to you, check the product listing for a 9V terminal or USB-C jump start before buying.
Is a physical key override better than a 9V terminal?
It depends on your habits. A key always works without any battery, but it means carrying a key and choosing a keyed cylinder. A 9V terminal keeps the lock key-free but requires you to have a 9V battery available.
Can I use a USB power bank instead of a 9V battery?
Some newer locks offer USB-C emergency power, which lets you use a phone power bank. This is less common than 9V terminals, so confirm the specific model supports it before relying on it.
How long do smart lock batteries usually last?
Most AA-powered deadbolts last roughly six months to a year depending on usage, Wi-Fi activity, and temperature. Cold weather and frequent remote access tend to shorten battery life.
Will a smart lock with emergency power fit my existing door?
Most full deadbolt replacements fit standard US door prep with a 2-3/8 inch or 2-3/4 inch backset. Retrofit models like August or Bosma depend on your existing deadbolt brand, so check compatibility before ordering.
Our verdict
For most US homes, the Schlage Encode Plus offers the best mix of built-in Wi-Fi, Apple Home Key, and a clearly marked 9V emergency terminal. If you want to spend less, the Ultraloq U-Bolt Pro WiFi and Bosma Aegis both include emergency power at lower prices. Whichever you choose, keep a spare 9V battery somewhere you can reach from outside, because that is what turns a backup feature into a real rescue.