Yale Connexis L1 Battery change

Try resetting your lock and see if that helps.

Also keep in mind that battery level fluctuations are normal, especially as the battery wears down.
This is because as you use the lock it draws current from the battery, this causes the battery voltage to drop. The more your use it and higher the current drain the higher the voltage drop. When voltage drops the lock registers a lower battery level.
When the lock is left unused for a while, the voltage recovers (when left along for a long while it returns to no load voltage) and hence the lock registers a higher battery %.
Essentially as the battery wears down more it has less capacity and the impact of a high current drain causes a higher voltage drop temporarily.
This is particularly more susceptible to alkaline and NiMH batteries which have deep voltage curves. If you want to avoid this try using 1.5v lithium batteries which have a very high current capacity and almost flat voltage curve.

See this post for an examples of differences in battery voltage curves.

In general for deadbolt locks it is very advisable to change the batteries when they drop below 50% as they start getting unpredictable with high current draws (like when the motor is used) and can cause a lock shutdown if the voltage suddenly drops too low.

See this post image for suggested battery levels thresholds for different devices