How Long Do Smart Lock Batteries Last?

The short answer

Months. Not years, and not the five years a coin-cell doorbell sensor might give you. Of the five smart locks we cover, exactly one brand publishes a runtime: Schlage states that the Encode Plus runs on four AA batteries with up to six months of typical use. Yale and August publish the battery type (AA cells) without a runtime, the Wyze Lock Bolt is rechargeable, and the Level Lock+ uses a single CR2 cell. Where a maker does not publish a figure, we do not fill one in — that is the whole point of this site.

So plan for a few months on any Wi-Fi smart lock, treat the app’s low-battery warning as the real specification, and buy a lock whose dead-battery behavior you are comfortable with. The last part is the one people skip, and it is the only part that can leave you standing outside.

Why the range is so wide: Wi-Fi is the battery story

A smart lock spends almost no energy turning the bolt. It spends its energy staying reachable. That single fact explains every number in this guide.

A Wi-Fi lock keeps a connection to your router so you can check the door from the office and let someone in from the supermarket. Yale is explicit that the Wi-Fi module is what is “required for remote access, and additional voice and smart home integrations” on the Assure Lock 2, and Schlage’s selling point for the Encode Plus is built-in WiFi with no additional accessories. Convenient, and it is why both locks want four AA cells.

A Bluetooth lock only wakes when your phone is in range. The Level Lock+ runs its whole life on one CR2 cell because it does almost nothing until you walk up to the door; its remote access comes from Apple Home using an Apple TV, iPad or HomePod as the hub, which means the power-hungry part of the job is done by something plugged into the wall.

Two more drains are worth knowing because they are both optional. Auto-unlock and geofencing keep the lock listening for your phone, which is the convenience most likely to cost you a battery change. And traffic: a family of five turning the bolt twenty times a day works the motor far harder than a couple who leave once.

What each maker actually publishes

The fourth column is the one to read twice. A smart lock with a dead battery is not a security problem; it is an access problem, and the brands solve it in four different ways. Two of them — the August and the Level — solve it by never removing your keyed cylinder in the first place, because they mount on the inside of the deadbolt you already own. August says it in one sentence: the lock attaches to your existing door lock, on the inside of your door over the deadbolt, so you can still use your keys.

Yale solves it with a key in the box and says so without hedging: the lock is battery powered so you still have access during a power outage, and “if the batteries die, you can always dig out your back-up key (included).” Wyze solves it without a keyhole at all — the Lock Bolt has a fingerprint reader and a 4-to-8-digit keypad code instead, and Wyze publishes the fallback: if the batteries die while you are away, the USB-C port allows a brief charge so you can get in. That works, and it requires you to be carrying a USB-C battery pack or to have a neighbor who is.

How to never be locked out: four habits

None of this is complicated, and all of it is the difference between a smart lock being invisible and being a nuisance.

Turn the low-battery notification on and act on the first one. Every lock here warns you in the app, and Wyze also flashes a red indicator on the lock itself when the battery is low. The warning is generous; people ignore it twice and then get surprised.

Keep the right cells in the house. Four AAs for the Yale, Schlage or August; a CR2 for the Level, which is the one you will not already own. Buying the spare at the same time as the lock is the cheapest insurance in this entire guide.

Decide where the backup lives. A back-up key in a drawer inside the house is not a backup. Either someone else has one, or it is in a sensible lockbox, or your plan is the keypad code — in which case make sure a second person knows it.

Change batteries on a schedule, not on a warning. If your lock publishes six months, change at five. If it publishes nothing, write down the date you installed them and watch how long the first set lasts; the second set will last about the same.

The locks that make a dead battery a non-event

These four are the picks from our wider best smart locks ranking, ordered here by how little a flat battery would bother you. Every one of them is a one-time purchase with no subscription, so batteries are genuinely the only running cost.

If the battery question is the thing making you hesitate, the honest recommendation is a retrofit lock: the August or the Level both leave your keyed cylinder exactly where it is, which turns a dead battery from a problem into an errand. If you want the Wi-Fi convenience with the least fuss, the Yale or the Schlage are the two to choose between, and both are on our Alexa lock list if voice control is part of the plan.

One thing batteries are not

A reason to avoid smart locks. The failure mode is slow, signposted weeks in advance, and solved by a two-minute battery swap — which is a far better story than a mechanical lock seizing in January with no warning at all. What batteries are is the reason to read the dead-battery row before you buy, and the reason a lock with a keyhole or a USB port is worth slightly more than one without. For the security side of the question, which is separate and more interesting, read are smart locks safe? and are smart locks worth it?