I have 3x SNZB 02D devices all purchased at the same time just over 6 weeks ago and have noticed a peculiarity with the battery indicator that has effected all three the same within within a few days of each other. The battery condition as reported on the device screen icon and iHost device card drops from 100% to 64%. The batteries removed from the devices measure 3.0 volts and on reinserting the same battery the display and iHost again report 100% battery capacity without it falling in value. All of the devices are in an area that has a temperature of around 23deg C. Has any other SNZB 02D user experienced this ? Thanks.
Yes. Some batteries and contacts cleaned then re-inserted. Created the following graph which shows which devices this was done on. Have just left them since, to see how long they last.
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Thanks for sharing your graph and I can see that 2 of your devices exhibited the same 100% > 60% drop in a short space of time as mine did. Iām using the original batteries that were supplied with the devices so will leave them to see what happens.
The CR2450 coin cells in some of my motion (Aqara P1) and temperature (SNZB-02P) sensors have been running for almost two years and are still functioning.
I recently measured the voltage of P1ās batteries, and it registered at 2,9V. When brand new, these cells typically show around 3,2ā3,3V, and they drop to 2,6ā2,7V when the sensors stop responding. This means the battery is currently at approximately 55% of its usable charge. In other words, after about 750 days of operation, only half of the battery capacity has been used. This P1 sensor operates in the kitchen, where movement is frequent, especially with my cat adding at night. It also reports illuminance. The detection interval is set to 60 seconds. So, after 6 weeks of usage, you shouldnāt notice any significant battery drain.
@Ramsdale makes a valid point about contacts. The air we breathe isnāt exactly pure, and when you factor in humidity, it further impacts the contacts, leading to voltage drops.
Doing a bit more testing Iām now convinced that the SNZB 02D has bugs in software version 2.3.0. for example
- In removing and replacing the battery it straight away shows a battery value of 18% remaining both on its screen icon and iHost.
- Same scenario but this time only the high few bars on the display icon, but iHost shows battery capacity as 100%
With the battery removed there is a residual voltage of a few millivolts at the device battery contacts that suggests itās internal capacitors remain charged.
For this device the temperature and humidity readings seem reliable but for the moment Iām going to ignore the battery condition indicator and rely on the iHost device activity log to make sure the temp and humidity are being updated regularly.
Youāre right. Thatās very likely. Letās hope that eWeLink guys take a closer look. But reporting battery levels is a weak point of almost every known to me Zigbee device. For example, TRADFRI open/close remote reports randomly various values (from 43% to 100%), although the cell was replaced a week ago for a quality one. And one thing more, end battery-powered devices are very ālazyā reporting this parameter. This we should bare in mind.
Re: the lazy battery reporting.
Iām using SNZB 02Dās in Home Assistant.
I take notice every few weeks to see if there has been a change in value.
I can then look at battery āHistoryā and see exactly when and what values have been reported.
For interest, I add them manually into a spreadsheet, which is where the earlier graph was produced from.
What would be nice then is, if the battery voltage was actually measured with a DVM each time. But that is not possible without removing each battery and that may have a number of consequences:-
Would the indicated battery level return to 100% again?
Or maybe some higher value than was just being indicated.
And:
Is this because the contacts have been disturbed?
Is it because the heat transfered from handling has had some effect on the battery?
Is it triggering / resetting something in the device measurement cct?
Software bug?
It would also risk loosing the device connection to Home Assistant and re-connection to HA is not something I want to have to do often.
It is interesting that the humidity peaks in the bathroom can be seen when a shower is used. Also in bedrooms overnight, by people simply breathing. It doesnāt happen if a room is not occupied or the door is left open.
But thatās a bit off topic.
Thanks and the observation about the humidity rising in the Bathroom while having a shower-- I use SNZB 02 (the device without the display) in the one of our bathrooms to trigger a switch that controls the extractor fan in there to operate when the humidity rises above the preset level. Iāve stuck with Sonoff scenes for all of my automation. Iāve made a length of foil insulated for most of itās length with clear sticky tape but uninsulated at each end so that one end sits between the battery and its centre connector- with that I can measure the battery voltage accuratly with the device operating. I can see that there are several issues posted in this forum about software problems with this device. Will keep an eye on what happens and keep the forum updated.
I just setup the same for my bathroom fan with a SNZB 02D and a ZBMINIR2. Works very well with a smart scene triggering the fan at 65%. I tested two 02D and two 02 devices in the bathroom for a couple of weeks before I set it up and the 02 devices were reading circa 15% higher on humidity than the 02D.
I have similar battery issues with the SNZB 02D. The one in the garage seems to eat batteries but now Iāve read this I expect Iām seeing the same issue. Please post your findings Alan.
I like Alans idea of using foil and sticky tape.
I wish Iād have thought of that a long time ago.
I did try powering one SNZB 02D located outside with two AAA batteries. That device kept dropping off the network every few days and I wondered if it was power related causing poor signal. (Involved soldering small wires to the contacts in the module).
However, It made no difference to it dropping off the network.
I should have thought about the foil strips idea then. Iāll try and add them and then get voltage data.
I also had three of these sensors, it is true they chew batteries. I now use ThirdReality Door Sensors that are better with battery consumption
Taking DVM readings of the battery voltage with the the SNZB -02D as the load (using the foil strip method detailed in my earlier post) I found: Initial insertion of Battery - Voltage 3.01 v, the device display (*see below) and iHost Card for the device show capacity as 100% after a few hours the Voltage measured was 2.99 volts, the device battery icon was just an empty rectangle and the iHost Card for the device showed capacity as 18%. Took the battery out, removed my foil āsensorā, reinserted the same battery and immediately the device and iHost display showed 100% again.
"during the tests the battery indicator on the device would only display the 3 bars in the right hand side of the rectangle for 100% capacity and the paired/ connected icon was not displayed at all although iHost was receiving Temperature and Humidity information throughout.
I was able to forget and re- pair the device several times without any problems but it didnāt resolve the display issues mentioned in * above, which just eventually corrected all by itself.
I also note that the SNZB 02D manual states that to change the display from the default DegC to DegF the button has to be pressed twice. What I found was that they have to be in rapid succession and any number of multiple presses 2, 3,4ā¦ will change the temperature format.
In conclusion I believe that these devices have a number of software issues. For the question of remaining battery capacity I would ignore the % shown and only change the battery if the device stops sending temperature and humidity information to what it is paired with.