Battery Life for smart Doorlocks

@JDRoberts , you’re right, Lithium batteries do have a different discharge curve from Alkaline batteries which creates it’s own challenges (and advantages)

@danryan28 see this post for a look on how different battery chemistry work.

While lithium batteries have 2x-4x the the battery life of Alkaline batteries (depending on type of use) they have a much flatter voltage curve. Most locks, including Schlage, Yale, Kwikset etc use this “voltage” to determine the remaining battery life. They are tuned to use Alkaline batteries. Having said that Schlage Connect locks are very “poorly” tuned to even Alkaline batteries. Without getting into the technical details of how these locks calibrate batteries and the “right” way to calibrate batteries (we had worked with Blink on this on extensively), keep in mind that Schlage connect locks tend to “overestimate” battery life, ie. at about 50-60% battery (alkaline) they will suddenly die (the voltage falls below minimum voltage required to power the lock).

See the first post of this topic for a list of recommended battery thresholds:

Yale on the other hand does a very good job with it’s battery calibration of it’s deadbolt locks and you can use it down to even 20% or so (30% to be safe).

Having said that, do if you now decide to use Lithium batteries (1.5v - keep in mind and not the 3.7v versions) as @ritchierich is using, you’ll have great battery life but you will need to “experiment” to find out at what % your lock goes dead. For example with Schlage connect lock expect the battery to “die” at about 80-90% battery reporting with Lithium batteries. It may seem high but that’s due to the voltage curve I spoke about earlier, so while it may last longer it you need to reclibrate your own expectation on when to change the batteries.

Maybe @ritchierich can share the thresholds he is seeing with using Lithium batteries and when they die on the lock he is using.

The other thing to note is that the deadbolt mechanism should be “buttery” smooth. If there is any resistance or scraping it will dramatically increase the load on your motor and consequently drastically impact your battery life. You may need to realign your door/frame/cutouts to ensure it’s a smooth unhindered operation for best battery life.

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