One thing in home automation you will run into is the need for batteries of many types. I have more different batteries than I ever imagine owning as this varies by need and vendor. A few thoughts from my learnings:

• Use what the manufacturer recommends, that’s the best course of action, that’s all you need to know the rest below is optional 😁 
• Use Alkaline batteries (most of the time): they are ideal as the voltage in the battery drops gradually and not sharply like with rechargeable and Lithium ones. Here is a graphic to show what I mean from Battery University:
  
  As you can see the alkaline type does not drop sharply so the systems you will use will see when it’s time to change batteries. NiMH, Lithium and rechargeable batteries will not necessarily give you that same experience so you will miss alerts or be alerted too late. This is especially important when you don’t live at the same home as the Alzheimer’s patient. I would hate to drive 3 hours to swap 2x AA’s.  Last but not least, before buying anything, check the manufacturer’s requirements, like the Nest Protect smoke detector wants Lithium Energizer’s, Ultimate flavor and personally I just follow these instructions. Just a reminder they can sometimes leak so if you leave a device unused for an extended period of time do remove them to prevent damage to the device they’re powering.
• Zinc-carbon batteries: a good option as they are less expensive and good for low-drain devices like remotes or sensors. On the flip side, they have a shelf-life of 3 years and expect to change them a bit more frequently. Unlike alkaline ones, they do not leak.
• Don’t cheap out: low-cost usually means shorter life spans so you don’t really gain anything other than annoyances. Use trusted brands, not the weird ones on online stores, if you don’t recognize the brand don’t trust it. When I used an August Smart Lock at our house I used the Duracell Optimums as I did not want to be bothered therefore paid for peace of mind. Not sure if that’s the best bang for the buck but it worked for me.
• Careful with reviews: some sites provide reviews and that’s super, but what most readers don’t realize is that many sites recommend as #1 the ones they get the most $s for referring to an online store. I tend to trust sites which show review data and results Vs a pros & cons listing. This CBC article does a good job on this topic. This site does a deep dive if you feel like learning more.
• Buy extras: when you need a battery you need it now. Buy extras and make sure to have some on-hand, systems which we pay good money for to deliver results for our loves ones need to work, final. Plus delivery times can be “entertaining” sometimes on the rarer battery models, so identify in your area where the electronic/electronic/industrial parts stores are, they’re not just for professionals and are full of other toys.
• Plan your tech choices: some devices will consume more than others and one key thing is the connectivity it uses. Wi-Fi will notoriously consume batteries faster than Bluetooth, ZigBee and Z-Wave. With Thread arriving, I would expect it to have the same type of power hunger as ZigBee. For smart locks here is a rule of thumb I made up based on reading on the topic and my own experience:
  • Wi-Fi: expect your batteries to last about 6 months and less if it gets cold
  • Bluetooth, ZigBee & Z-Wave: 18+ months is achievable. I installed my ZigBee smart lock about 7 months ago and my battery is at 88% of charge. Do note it’s the one which came with the device so I should probably get more lifespan out of a premium one.

For those who wish to geek out on batteries, how to stop using them and smart homes I suggest you watch this clip (warning it involves.. soldering electronics! I’m not there yet either but feeds the idea bucket):