Why does my smart lock battery die so fast?

The usual causes

A smart lock that burns through batteries is almost always working harder than it should, or running on the wrong cells. Four things are worth checking, roughly in this order.

The door and frame no longer line up. Motorised deadbolts push the bolt out themselves, so a door that drags or a bolt that rubs the strike makes the motor work harder on every lock and unlock. Schlage's Sense manual explains why alignment matters: "Because the bolt on this lock is extended automatically, it is important that the door and frame are aligned."^[1] Its checklist is a good test for any brand: you can lock the door without pushing, pulling or lifting it, the alignment stays the same as the seasons change, and there is room for the deadbolt to extend 1" into the frame.^[1]

That same manual describes how a misaligned door costs power. The lock has both a low power and high power mode, tries low power first, and switches to high power if that fails. After three times using high power, it will always use the high power mode instead of trying twice each time, and the manual says you may want to adjust your door or frame to conserve battery power, but that it is not necessary.^[1] A door that sticks in humid weather and closed fine in winter is worth checking for this reason.

The wrong batteries. Check the manual for the cell type your lock was designed for. The Sense calls for four high-quality alkaline AA batteries and warns that lithium batteries may cause undesirable operation.^[1] A pack of bargain cells or a mix of old and new can behave the same way as a dying set, so use a fresh matched set from a known brand.

A poor connection. If the keypad does not light up, Schlage's guidance is to install fresh batteries and make sure the battery connector is connected.^[1] If the lock still will not light up, the manual says to make sure its cable is connected and not crimped, which is a job for the manufacturer or a locksmith once the lock is assembled.^[1]

Temperature. Locks are rated for a range. Schlage lists 14 degrees F to 120 degrees F for the inside lock body of the Sense and -31 degrees F to 151 degrees F for the outside body.^[1] A lock in direct afternoon sun or on a very cold exposure is working near its limits, and your own model's manual states its range.

Work through it

Start with the cheapest checks, because they cost nothing. Open the door and run the lock several times, listening for a motor that sounds strained or a bolt that hesitates. Then close the door and lock it from outside, and watch whether the bolt goes out cleanly on the first try or needs two attempts.

If it struggles only when the door is shut, the strike plate and bolt hole are likely the problem and not the batteries. A small shift is often a loose hinge screw that has let the door sag. Tightening hinge screws is ordinary hand-tool work.

If the lock moves freely but still drains quickly, swap in a fresh matched set of the exact type the manual specifies, and see how long they last. Note the date, so you have a real number to compare against.

What your lock's alerts tell you

Schlage says its smart locks are designed to provide low-battery alerts before the batteries die, and depending on the model you may get app notifications or see a low-battery indicator on the lock.^[2] Treat an early or repeated warning as a symptom to investigate, not just a reminder to buy more batteries. If you are changing them every few weeks, something above is wrong.

You also have a safety net: Schlage says all its electronic locks offer backup access with either a physical key or a jumpstart port for temporary power backup.^[2] Know where your key is before the batteries fail, and keep a spare outside the lock.

Old batteries

Do not toss dead cells into a drawer. The EPA says that in most communities alkaline and zinc carbon batteries can be safely put in your household trash, but it recommends sending them to battery recyclers or checking with your local or state solid waste authority.^[3] The EPA says not to put button-cell, coin or lithium single-use batteries in the trash or municipal recycling bins. Tape each lithium battery's terminals or bag it separately first, because a lithium battery may spark and cause fires if damaged or the terminal ends touch.^[3]

Stop and call a pro if

• The bolt binds even after you tighten the hinges. A door that has dropped, swollen or shifted out of its frame may need planing or the strike moved. A handyman or carpenter should fix it.
• The lock fails to extend or retract after fresh batteries. The manual's own steps for a lock that will not light up are fresh batteries, a connected battery connector and an uncrimped cable.^[1] If those do not help, contact the manufacturer or a locksmith before forcing it.
• You are locked out. Use your backup key or the jumpstart port first, then call a locksmith.

Next steps

For the install checks that prevent this, see how to install a smart lock, and for a replacement schedule, how often to change smart lock batteries. If you are unsure about the lock itself, read are smart locks safe and what a smart lock costs installed in Virginia. More topics are in smart home answers and the smart home guide.

When the door needs more than a hinge screw, describe the job once and local pros can quote it.