Button Battery Discussion

I have a bunch of Aeotec/Smartthings door sensors and buttons. These guys are running CR2450 batteries. I’ve been buying inexpensive “off brand” batteries, in bulk - like, a 10 pack for about $7. I’ve noticed an issue though - - there’s this weird power drop off curve; a device will be reporting around 50% charge, but will then be dead in the blink of an eye. It literally goes from 50% to dead so fast that Smartthings doesn’t even notify me that the device’s battery is low. Sometimes a battery will last months, but sometimes it’s just a few weeks.

Is this just how these button batteries work in general or would I have a better experience spending more money on a premium brand like Duracell (which cost more than double, compared to the current batteries I’m using)?

What is everyone running in their systems and what has been your experience?

As a sidebar: The door sensors that come with my alarm system run 1x AAA battery each and last for years. I suppose though, that you get a lot more bang with 3 volts than you do with 1.5… it’d be nice though if Aeotec redesigned their sensors to use 2x AAA batteries.

Try it and report back?

Some drivers have voltage-percent-mapping, but we don’t know how it looks like in the Aeotec drivers.

And now compare the discharge curve of a no-name battery with one of the quality brands.

in my opinion, and with absolutely no statistical evidence, the location of the device in relation to the radio network and the frequency of data changes are more important than the quality of the (same type of) battery itself.

for a good mixed calculation, I therefore equip the devices that die a battery death more frequently in the past with high-quality batteries and the others with cheap ones.

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Cheap batteries are definitely prone to early failure. Regardless of shape or voltage. It’s just a matter of engineering quality.

@stillerson ‘s approach of using higher quality batteries specifically for those devices that have had problems in the past makes a lot of sense.

As an engineer, I don’t use the cheap batteries, but that’s just me. :man_shrugging:t2:

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Compare this to the mapping table I’ve posted above.

https://www.researchgate.net/figure/OCV-DOC-curve-for-a-fresh-620-mAh-CR2450-Li-MnO-2-battery-which-is-discharged-with-1-mA_fig1_385398092

That looks like the mapping for a rechargeable lithium ion battery.

All rechargeable batteries have that kind of mapping regardless of form factor or size.

It’s why some device manufacturers tell you not to use rechargeable batteries: you don’t get the low battery alerts that you would with a non-rechargeable

First graph is from a rechargeable battery, second graph from a non-rechargeable.

The mapping table is just an example, of course! They all look different. Some of them are linear (which doesn’t make sense at all) and some are non-linear.

This could be solved by shifting the voltage/percentage map.

The second graph is not for the kind of battery you would use in a home sensor. From the link you gave:

This article presents a novel aging-coupled predictive thermo-electrical dynamic modeling tool tailored for primary lithium manganese dioxide (Li-MnO2) batteries in active implantable medical devices (AIMDs).

A standard (nonrechargeable) alkaline battery has a graph that looks like this:

Non-linear, I know…

Now the question is how the voltage is mapped to percentage. The user expects percentage of time left and not the voltage.

Nope…

The second graph comes from this page:

That’s why I choose two different sources after all…

At the end, none of them are linear.

At least in the US, you can still get alkaline button batteries. But the main point is that the discharge curves are different depending on the battery chemistry.

The user manual for the device should say what the recommended batteries are.

If they have set their low battery notifications based on the assumption of alkaline batteries, they won’t work correctly when lithium batteries are used. But the user manual should indicate what the device manufacturer is expecting.:man_shrugging:t2:

Doesn’t really matter in my opinion.

Google Image Search: cr2450 discharge curve

The real question is: what does the voltage/percentage table look like in the driver.

And yes, that table would only be accurate if it would take different battery chemistries and the environmental temperature into account.

But if it’s completely linear, it’s probably not what we want.

The original issue:

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My own experience is that I go through the cheap batteries much faster than the brand name ones like duracell. It’s almost a 2 or 3 to one ratio. I am now only buying the brand name batteries.

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Those LiCB batteries are the ones that I’m actually using. I honestly thought i was getting bad batteries, my some of my devices die so quickly. I bought a battery tester to test them fresh out of the package and it turns out that I have been getting a few bad batteries, here and there - every third or 4th battery I take out shows up “yellow” on the tester.

I replaced 3 fully dead batteries on 11-24-2024, with batteries that I confirmed were ‘full’ before installing:

Door 1 - online with 22% charge
Door 2 - offline (battery dead) last reported charge = 24%
Button - offline (battery dead) last reported charge = 46%

Is 2.5ish months normal for button batteries?

Again, button batteries come with different chemistries from different brands and they will have different life expectancies.

Beyond that, it depends very much on the specific use and location of the device that has the battery in it. A motion sensor in a guest bedroom that only gets triggered once or twice a week is going to have a battery that lasts much longer Than a motion sensor in the kitchen that gets triggered more than a dozen times a day.

In addition, if the battery has adjustable sensitivity, then the parameters will make a huge difference. For example, fibaro says that their multisensor at factory settings can expect to have a battery that lasts between one and two years, but if you set it to its most sensitive, the batteries might only last three months. :thinking:

Some devices are better at managing battery life than others, so the brand and model of the specific device also factors in.

Finally, as has already been mentioned in this thread, if your device is right on the edge of range for communicating, it may have to send the same message two or three times in order to get through and then that using 2 to 3 times as much battery life. So the relative location of the device with the battery to its parent device (the one that repeats for it) can also make a very big difference.

Most of the Zigbee devices that work with SmartThings are spec’d to have a typical battery life of one to two years when

  • used with The recommended battery brand and model
  • at the factory default settings and
  • well positioned relative to their parent
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Doesn’t mean much. Look at the discharge curve again: they start at roughly the same voltage (what you interpret as “full”) - the Y axis. What counts is how long they can deliver that - the X axis. And that’s why the voltage/percentage table exists:

last reported charge = 24%
last reported charge = 46%

Just get some batteries from a reputable brand and see how it goes.

My contact, temperature, motion sensors from Tapo use the exact same battery type and they last between 1.5 and 2 years.

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