Product: All electronic deadbolt locks, all smart locks
Battery operated devices has been around easily for more than 50 years. In past 10 years, residential door locks have been slowly adapting the electronic locks due to the popularity of hotel key fob, and office key fob system. More importantly, the introduction of bluetooth and WiFi in mobile apps that allows more transparent usage of door lock. This also allow phone, and smartwatch be used as key to unlock the door.
Most of the residential locks are using AA batteries, unlike commercial models which uses power line with power adapter. This blog post mainly to point out that the company that designed it, especially Kwikset, are not following the industry standard that battery operated devices should consider the depleted battery as 0.9V where the new battery is 1.5-1.6V.
I recently acquired 2 Kwikset 264 electronic deadbolt lock and found that the lock is complaining low battery when the battery is 1.3V. This means it still has 0.4V to be considered depleted, yet it starts to stop to operate, and consistently buzz the alarm. The lock is not able to lock, unlock, or auto lock. Further investigation, this seems to be affecting the entire line of electronic locks:
- Model 264, 275
- Kevo series smart lock, e.g. Kevo Convert, Kevo Contemporary, Kevo Traditional
- Premis Apple HomeKit Smart Lock
- SmartCode 915, 916, 914, 913, 912, 911, 910, 909
- Powerbolt 1, 2
There are few factors why battery operated devices need to work in range of 0.9V - 1.6V:
- Industry standard - it is used to measure the battery capacity, and toys industry has long adopted that
- Fully used the energy stored in batteries
- Reduce waste due to not depleted batteries
- Extend longer operation of the devices
- Rechargeable battery can be used to further conserve the battery waste
I used Kirkland alkaline battery, and it last ~ 4 months. I know that these battery hardly has 2000mAh, but if they can allow it to operate until 0.9V, it should able to last 6 months. Curerntly, it only used up 42% of the battery's capacity, and 68% wasted. As consumer, we would like the lock to operates longer, and won't get locked out by the electronic lock. The landlord might gives the PIN code to tenant, while keeping the key for personal used. Property manager also doesn't want to visit every house to swap the battery every 4 -6 months.
I am a big fan of NiMH AA for last 20 yr, and their 2500mAh capacity and long life have been proven in my Panasonic phones to be very cost effective.
Hope that these manufacturers are able to see my blog post and revise their design.