Keeping our devices charged can be tricky. Every screenshot we take shows our iPhone battery at under 50 percent. It’s not a big deal if our iPhone runs out of battery, but if that happens to our smart lock, we could end up locked out of our house.
That’s why we always opt for smart locks with emergency power options. And we know we’re not the only ones who let our batteries get dangerously low before charging them. That’s why we created this guide so you can get the same smart locks as our home security experts use.
>> Read More: 2025 Smart Door Lock Buying Guide
FYI: Almost every smart lock offers a manual backup mechanism for unlocking it in case of an electronic failure, but we didn’t get a smart lock to still carry house keys with us everywhere we go. That’s a big reason why we prefer smart locks with emergency power options.
Understanding Smart Lock Power Systems
Here’s a look at the Kwikset smart lock that we bought with our Vivint home security system.
Smart locks need continuous or on-demand power to operate motors, wireless radios, and processing chips. Most smart locks use one of three primary power sources:
- Replaceable battery-powered locks typically run on four to six AA batteries. Battery life ranges from three months up to a year depending on usage frequency, the type of battery used, and wireless connectivity demands.
- Rechargeable battery locks use internal batteries that last two to six months per charge. The battery pack is usually removable for charging.
- Hardwired locks, although rare in residential settings, connect directly to household electrical systems. They typically have battery backup in case of power interruptions.
>> Recommended Products: Vivint Automatic & Smart Door Lock Options
Power Consumption Variables
Beyond the power system, you also need to consider how the lock uses power to figure out its battery life and emergency power needs. Wireless connectivity protocols consume the most energy, with Wi-Fi locks using up to seven times more power than Bluetooth-only models.1
We find that cold temperatures also affect battery performance. Our testing shows smart lock batteries lose 25 to 40% of their capacity in temperatures below 20°F. If you live in cold-climate areas, you should really have emergency backup power for your smart locks.
Of course, how often you lock/unlock your door will also affect battery life. Our front door smart lock, which we use more frequently than the one on our back door, needs battery replacement every eight months. Meanwhile, our back door smart lock hasn’t needed a battery replacement in more than a year.
Did You Know? Smart door locks are one of our favorite smart home components for burglar proofing your home. They immediately signal to criminals that you take your home’s security seriously, encouraging them to find a different target.
Types of Emergency Power Options
Nowadays, most smart locks incorporate some type of emergency power solution:
- Built-in Backup Batteries: These systems maintain a secondary battery that activates when main power drops below operational thresholds. Most use a small, replaceable battery for backup. That way, you can easily replace it after use and know that your backup power will be functional the next time you need it.
- External Battery Packs: The second-most common backup power option is an external battery. Some smart locks have hidden external battery terminals where you can attach a 9V battery to power up the lock temporarily and gain access to your home.
- Physical Key: Instead of a backup power supply, some smart locks offer a physical key as a backup method of entry. This means you’ll either need to hide the key or keep it with you, though, in case the lock’s main power supply dies.
Key Features to Look For
Our testing revealed a few key features required for a reliable smart lock emergency power solution.
Low Battery Alerts and Monitoring
Effective battery monitoring prevents emergency situations before they occur. We prefer smart locks that offer several ways to notify us of a low battery, including:
- App notifications that send low battery warnings when the level reaches a certain threshold.
- Battery level indicators that show precise remaining power as percentages rather than simple “low battery” warnings.
- Usage-based predictions to calculate estimated remaining battery life based on actual usage patterns.
Pro Tip: If you own a security system, we recommend buying a compatible smart lock. That way, every time you pull up your security system app, you’ll see your smart lock’s battery life. Check out our guide to ADT’s smart lock options for a look at what locks you can pair with one of our favorite security systems.
Charging Flexibility
Smart locks with flexible charging methods are easier to keep charged so you don’t need to use its emergency power. Proprietary chargers are our least favorite. Losing a single cable shouldn’t prevent you from charging your smart lock. We prefer smart locks with batteries that can be charged with a micro-USB or USB-C cable.
Top Smart Lock Recommendations
We tested nine smart locks, assessing their emergency power solutions, advanced smart features and overall security. August, Yale, and Schlage topped the competition in all three categories. While we don’t think you can go wrong with any of the three, your best option will depend on your specific needs. We’ll go over our personal experience with all three so you can pick the best smart lock with emergency power options for you.
August — Great for Power Alerts
All August smart locks feature a physical key override in case your battery dies. We found August exceptionally good at notifying us of a low battery before we needed an emergency access solution, though. They started sending us notifications once our battery hit 25 percent giving us plenty of time to change our lock’s four AA batteries.
What We Like:
- DoorSense notifies us if we leave our door open or unlocked
- Auto-lock feature ensures our front door is always protected
- Low battery alerts include daily emails and push notifications
- Installation does not require a complete replacement of an existing deadbolt
What We Don’t Like:
- Relatively short battery life
- Different models use different battery types
- Hardware for a new deadbolt costs extra
Yale — Most Reliable
With over 150 years creating locks, it’s hard to beat Yale’s reliability. After testing a Yale smart lock in our home, we can confidently say they translate that century-old experience into their smart locks, too. While they don’t have the standout smart features like August, their locks incorporate an emergency power supply that functions off of a nine volt battery with some models also working with a physical key.
What We Like:
- Backup power supply is easy to access
- Intuitive keypad
- Collaborates with Google Nest and August
- Reliable company with a long-standing history
What We Don’t like:
- Some models do not have a physical key backup
- Most models require a complete deadbolt replacement
- Large list of product options can make it difficult to pick the right product for you
Schlage — Great Physical Override Option
Schlage has almost as many years creating traditional locks as Yale. Except, Schlage sticks more to their traditional foundations. All of their smart locks feature a standard physical locking mechanism with a key. Of course, they also have a mobile app, smart home integrations, and a keypad, but that emphasis on a physical key makes emergency access simple.
What We Like:
- Nearly indestructible locks
- Strong integrations with Ring products
- All locks feature a physical key
- Tap unlock feature for Apple Watch
What We Don’t Like:
- Limited smart home features
- All models require a complete replacement of your existing deadbolt
- Industrial aesthetic
>> Check Out: Ring Home Security Camera Review 2025
Keeping Your Primary and Emergency Batteries Charged
We know it might sound silly, but there’s more to keeping your smart lock’s batteries charged than just, you know, charging them when they die.
Battery Management Best Practices
Like we mentioned in the beginning, we’re not good at keeping our phone charged. But, we know we can’t take that lackadaisical approach to our smart lock. Here are three best practices we use to keep our smart lock batteries charged, so we only need its emergency power during emergencies:
- Battery replacement timing should occur at 20-25% remaining capacity rather than waiting for complete failure. This approach prevents unexpected lockouts while ensuring backup batteries remain fresh for emergencies.
- Purchase quality batteries that offer a longer lifespan. Premium alkaline or lithium batteries provide a significantly longer life and better performance in cold temperatures compared to generic alternatives.2
- Regularly replacing backup batteries, if your smart lock has one, keeps secondary power systems fresh and functional. We recommend replacing backup batteries every 6 to 12 months whether you’ve used it or not.
Testing Emergency Systems
Our team uses a consistent schedule broken down into monthly, quarterly, and annual tests to ensure backup systems will function as intended during actual power failures. Here’s what we use:
| Smart Lock Emergency Power Testing Schedule | |
|---|---|
| Monthly Test | Check the backup battery level in the mobile app. |
| Quarterly Test | Remove the main battery and test emergency power functionality. |
| Annual Test | Verify all emergency access features work including emergency power supplies and physical key overrides. |
Troubleshooting Common Power Issues
While consulting with everyday smart lock users, we noticed they experienced a few common power-related issues. Here are the three most common issues and how to resolve them:
Battery Drains Quickly
Excessive battery consumption often indicates configuration problems or environmental factors rather than lock defects. To extend your battery life, we suggest trying:
- Optimizing connectivity reduces power consumption by adjusting wireless settings and connection frequencies. Disabling unnecessary features like auto-lock sounds or LED indicators can extend battery life by 15 to 25 percent.
- Avoid extreme temperatures that accelerate battery drain. Simple weather shields or relocating locks to more moderate microclimates can double battery life in harsh conditions.
- Analyze usage patterns to identify activities that consume excessive power. Frequent app connections, unnecessary status checks, or malfunctioning sensors often cause rapid battery depletion.
Backup System Failures
Backup power systems occasionally fail to engage when needed, leaving you locked out despite having emergency power options. We find that most backup failures result from maintenance oversights rather than system defects. Here’s how to avoid these failures:
- Connection cleaning resolves many backup charging problems. Corrosion or debris on charging ports and battery contacts prevents proper power transfer even when backup power sources are available.
- Backup battery replacement addresses the most common backup system failure. Secondary batteries often sit unused for months, losing capacity even when not actively powering the lock.
- System reset procedures restore proper backup power functionality when software glitches prevent automatic switching. Most smart locks include factory reset options that preserve user codes while restoring power management systems.
Expert Insight: We recommend keeping backup battery cleaning contact points with isopropyl alcohol and cotton swabs every 3-4 months. Corrosion buildup is the leading cause of backup power system failures.
Emergency Access Procedures
Our Kwikset smart lock features a standard deadbolt keyhole to provide easy emergency access.
When all electronic systems fail, you’ll need to use the lock’s mechanical override option. To prepare for this situation, we recommend:
- Practice locating and using the physical key override in daylight conditions before needing them during emergencies.
- For locks that support external emergency power, keep a compatible battery in a location that you can access if you’re locked out.
- Write down your local locksmith service in case professional assistance is required.
Recap: What’s the Best Smart Lock with Emergency Power for You?
The best smart locks combine multiple emergency power solutions rather than relying on single backup methods. In our opinion, dual battery systems or external charging options, when used along with physical key overrides, provide comprehensive protection against lockout scenarios.
In that regard, it’s hard to beat August, Yale, and Schlage smart locks. Their solutions offer at least two backup methods along with robust smart home integrations and top-of-the-line security. Just remember, you still need to regularly charge, replace, and test your emergency power to ensure it’ll work when you need it most.
Frequently Asked Questions
- How long do emergency backup batteries last in smart locks?
Most backup battery systems provide 24 to 72 hours of operation, depending on usage frequency and environmental conditions. Dual battery compartments typically offer longer backup duration than integrated backup cells.
- Can I use regular AA batteries for emergency power backup?
It depends on your specific smart lock. Most smart locks that use AA batteries, use them as their main power supply, though. Always check manufacturer specifications for approved battery types.
- Do smart locks work during power outages?
Battery-powered smart locks continue operating during power outages since they don’t depend on household electricity. Hardwired locks need backup power systems or battery backup to function during outages, although hardwired locks are rare.
- How often should I replace backup batteries?
Replace backup batteries every 6 to 12 months regardless of usage to ensure emergency power availability. Primary batteries should be replaced when they reach 20 to 25 percent remaining capacity.
- What happens if both main and backup batteries die?
Most smart locks include physical key overrides or external power input options for complete battery failure. Some models accept 9V battery power applied externally for emergency access.
- Are solar charging options reliable for smart lock emergency power?
Solar charging works well in sunny climates with consistent exposure, but requires backup battery storage for nighttime and cloudy weather operation. Solar systems need 4 to 6 hours of direct sunlight daily for reliable power.
