Do you replace batteries by time or as needed?

Battery usage greatly depends on "foot traffic," quality of the driver and the health of the mesh. Devices that get a lot of traffic will need to be replaced more often, whereas those with low activity can go up to 2 years, maybe more. Also, a mesh that is not healthy will deplete batteries a lot faster. In my production, I replace the batteries as needed.


I have an outdoor air temp sensor for my Honeywell stat that I replace batts in every 2 years in the fall - it's just in a funky spot that's hard to access in deep winter or summer.

I replace the batts in the Yale lock on our most-used house door every fall as an abundance of caution.

Everything else is fly-to-fail.


As needed, unless it's a smoke detector where I do it once or twice a year as is often recommended (except I get lazy with the "smart" detectors sometimes that I guess are the scope of this question and wait until they start chirping--they are never my only detector in a room, just something I added, so I'm less concerned).

It may not surprise you to learn that I use Device Activity Check primarily to help me see when "as needed" ends up being.


One thing I have noticed since migrating to the C-8 is that batteries are draining much slower, and I think the battery life was generally pretty good before.

A big thank you for that handy little app. That’s what I’m doing as well.


Indeed, thank you for that. It's a key part of my notification method mentioned above. And it also has been invaluable in letting me know when one of my ZW15Rs has decided to go deaf-and-dumb again.

And while I'm handing out kudos, thanks to whomever also graciously wrote the 'Device Refresher' app, and to the HE team for including the ability to add battery notifications to the alarm functionality.

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+1 on using the Device Watchdog app. It's fantastic. (The Device Activity app is also great) It has allowed me to wait for a battery to either be below my threshold (20%) or fallen off of a dead battery and not reporting for 48hours.

Same, I thought I was replacing batteries way too often, but this has helped me realize I get 6months for most chatty devices (that have temp sensors) and a year+ for the rest.

The one exception is if we are about to go on an extended vacation, I will check the battery sensor of some items like water leak detectors and preemptively change them if it's been a while.

I run Device Activity Check.
I have emprically assessed each type of device and what the battery level really means, AKA about to die.
For the Aqara/Xiaomi stuff I have it report when Presense is lost.
I have 4 categories and get a notification in HE when any device gets to a threshold.

I use the device activity as well. I have no locks so if a water sensor is down for a day I consider it very low risk.

I do however have a sensor in the attic which is a pia to get to. So if I have to go up there and the old battery is more than 6 months, it gets changed.

because i have one house empty at all times.. when i leave there i replace all critical batteries whether needed or not . ie door locks.. temp sensors.. therms etc.

@JB_TX I use HSM to monitor all my batteries. Get a notification at 10% (was 20) and simply change them out... I also use Device Activity Check just in case as well.

I wait for the batteries to fail, then change them. Moved all that I could to rechargeable (CR2, CR123, AA & AAA).


You mean wait for the automation not to run when it should, then check the batteries? Sounds like me :joy:


Hehe, in some cases, yup. In others, I use Robert’s Activity Check app.

Looks like I need to pay more attention to it… I have redundancy for most of these, so it can take a bit of time until I start wondering why things aren’t working as well as they should…

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Me too. :joy: I've been getting a notification every evening for weeks but don't seem to care enough about those blinds (pretty much always closed this time of year) or basement temperature sensor (meh).

I'm thinking I should add an "every other day" option or something to avoid notification fatigue. But I guess that's why I added snooze...


I use device activity check and keep a spreadsheet. When there is no activity, the device gets a battery.

I log everything into a spreadsheet and look for consistency. If a device consistently stops functioning at a certain battery level I'll use device activity check to notify me just before that level (my door luck is one of these devices).

I use @kahn-hubitat's port of Battery Manager and set a 15% warning level and start watching it and replace the battery when reporting goes below 10%. Haven't had any devices die following that approach, which is key for WAF.

Same, but for tracking how often I'm usually replacing them so I can see if a device is getting odd battery drain. My devices are all CR123, CR2, and CR2302, except for door locks.

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What CR2 rechargeables are you using...I'd really like to switch to CR2 rechargeables. Already on rechargeables for AA & AAA, which aside from CR-2032 are the only batteries I use in any quantity.

I’ve been using these 880mAh 3V CR2 rechargeable batteries from AliExpress:

My first order, I got a set that came with a charger.

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Thanks! :slight_smile:

Presumably you're happy with the batteries and the charger. Any quirks or things you've noticed worth sharing?

Yes, very happy. Only quirk is that they don’t last as long as non-rechargeable. So, need to change then more often, but I got a bunch of extras so I always keep 3 fully charged and swap.

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