Battert in Shelly Door/Window 2 lasted only one month

  • My Shelly Door/Windows 2 lost power surprisingly fast and I'm wondering whether I should treat this as a battery problem or a shelly problem.

    Here is the battery percentage over time. The DW2 was installed on 18 july with battery at 100 percent and stopped working on 18 august at a battery percentage of 92 percent. The graph also shows that the DW2 stayed at 99-100 percent from 18 july until 8 august. Maybe it is a coincidence, but it is worth noting that the door was not operated between 31 july aug 7 aug due to absence, so it looks like opening and closing the door causes significant battery drain (tilt is turned off). Is this normal?

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    Apart from the battery going from 100 to 92 in just ten days, it is particularly strange that the device seems to have stopped working at 92 percent. (At least it stopped sending battery level updates.) So I measured the voltage of the batteries (Panasonic Lithium CR123A, both with a best before date 01-2030): one was 0.84 V and the other 2.47 V. When I checked again a few hours later (during which they lay on my desk), they had recovered to 1.33 V and 2.56 V.

    The fact that one of the batteries was basically completely drained while the other was still "ok" made me think that this was just a bad battery and that the problem will not occur once I replace both batteries. But even if this is true, I still find it strange that a battery can drop so extremely fast that the DW2 didn't even have time to report any battery level below 92 percent.

    Does anyone have any explanation of what happened here or suggestions for what to do? (I have already replaced the batteries and the DW2 was immediately back online.)

    Einmal editiert, zuletzt von tophee (5. Oktober 2021 um 06:56)

  • Hi,

    many factors affect the discharge cycles of the batteries:

    • Number of trips / per day
    • Services used (cloud, MQTT, COIOT)
    • Quality of the WiFi
    • Setup of the Shelly (DHCP or fixed IP)
    • Quality of batteries

    It is difficult to make specific statements about individual cases here.

    As a counterexample, I can tell you that my Shelly DW and DW2 have been running on the first batteries since 2020 (January, May and June).

    Here you will find a list created by forum members with the rating of different batteries. (written in German)

  • Oh, sorry,

    here it is.

  • Hi Guys, apologies for using English in this forum.

    I tried using 3.7/4.2V rechargeable Li-Ion cells in a DW-2.

    They were fresh from charge, so 8.4v total, rather than ~6v...

    Appears to have cooked the unit, with toasted semiconductor smell.

    Does anybody have experience with this, or used 4.2v batteries with the H&T?

    Thanks.

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