Kwikset Short Battery Life

That’s actually expected and explained above.

Rechargeable batteries have a lower operating voltage around 1.3V v/s 1.5V for alkaline batteries. Lock circuits are calibrated to cut off lock operation when the voltage falls below a certain threshold, e.g. 1.1V. The voltage discharge curve of a alkaline battery is longer so it takes longer to get to 1.1V where as rechargeable batteries get to 1.1V much faster hence the lock circuit powers down much faster. For that matter Lithium batteries have a much flatter voltage curve so they take longer to get to 1.1V (but i’ll happen much faster in the end like in a few hours v/s days) so they are able to extract the most juice from batteries before the lock does.

To make things more interesting is the difference between no-load and load voltage drops. When the lock draws a large amount of power from the battery (e.g. when operating the deadbolt), it causes a temporary voltage drop due to internal resistance of the battery. Rechargeable batteries have a higher voltage drop (it varies depending on chemistry, NiCD or NiMH, NiMH are better of the two) under heavy load than alkaline batteries (Lithium have the least), so it very likely that when operating the deadbolt the lock will suddenly “die” when using rechargeable batteries. Infact some locks like Schlage BE469 have a huge current draw and cause this phenomena even with alkaline batteries and so it’s recommended to change deadlock batteries at 60% instead of waiting for it to go lower. This is explained here and you can find some recommendations about it here.

Due to difference in battery chemistry/voltages and the lock chip cut voltages, rechargeable batteries are not recommended to use with locks.

Not that this helps, but my Kwikset 914 has batteries that are at least 4 months old. I am using high quality lithium ion rechargeable batteries. The door lock is used about 8 times a day (via SmartThings) during the week and more on the weekends.

The 914 is about 5 feet away from the SmartThings v2 hub.

Edit - they are NiMH batteries.

Lithium ion batteries are 3.6 to 4.2v, your lock needs 1.5v batteries. You’re probably frying your circuits. You should ONLY use 1.5v batteries like an Alkaline battery or at best a 1.5v Lithium battery and never a Lithium Ion battery.

I was mistaken. The batteries are NiMH

The rechargeable lithium ion batteries are for a quad copter. I should’t post half awake (or is it half asleep)

Depends if the glass is half full or half empty.

You may not get the full use of your batteries, see my post above and the link s in it which explain why, it’s related to the battery voltage of NiMH batteries which are lower than Alkaline and Lithium 1.5v so the circuit shuts down faster, depending on the voltage and load put on your NiMH batteries. When the motor runs it puts a heavy load on the batteries and if the battery can’t supply it the voltage tanks and it shuts off the circuit to the lock.

REF, for a steady state small current draw voltage curve:

Under heavy load the voltage will drop faster for lower quality batteries.

Yes, I read your post about how alkaline batteries are better. Perhaps in this application these batteries work well. The last time I swapped out the rechargeable NiMH batteries was in April 2019. Again, the lock is locked and unlocked from SmartThings 6 times a day and more on the weekends.

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