eWeLink should add an option “AAA Rechargeable” in “Battery Information” for door sensors. And of course send proper “Low Battery” notifications based on voltage.
Rechargeable AAA (NiMH) are not recommended for Zigbee door sensors.
They have high self‑discharge, lower nominal voltage (1.2 V), and larger voltage drops during TX pulses. This makes the sensor report incorrect battery levels, disconnect, or rejoin the network.
Adding a “Rechargeable AAA” option in the UI wouldn’t fix the underlying electrical characteristics. The sensor is designed for 1.5 V alkaline or 1.7 V lithium cells.
Ni‑Zn 1.6 V cells work better than NiMH because their nominal voltage is much closer to alkaline (1.5 V) and lithium (1.7 V). The sensor will read their battery level correctly and they won’t cause the typical Zigbee issues like dropouts or rejoining.
However, Ni‑Zn still have a very steep discharge curve and lower usable capacity than alkaline or lithium cells, so the real‑world runtime will be shorter. They work, but they’re not as stable as the primary cells the device was designed for.
From an ecological perspective, rechargeable batteries aren’t actually the greener choice in ultra‑low‑power IoT devices. Door sensors consume so little energy that a single alkaline AAA lasts 1–2 years. NiMH or Ni‑Zn lose a significant portion of their charge through self‑discharge alone, need frequent recharging, and wear out faster.
In practice, using one alkaline cell every couple of years has a smaller environmental footprint than repeatedly charging and replacing rechargeable cells that never reach their full cycle life in this type of device.
I’m actually using normal rechargeable AAA battery (1.2v), they’re working very well… I’ve no disconnects, rejoin and any other problem. The only problem that I’ve is the battery level indicador.
I was using alcaline before, they were lasting about 4 months not 1-2 years. That’s why I changed everything to rechargeable.
If NiMH cells work reliably in your device, that simply means your particular unit tolerates the lower nominal voltage and the voltage dips during TX bursts.
The underlying chemistry doesn’t change, though: NiMH always have 1.2 V nominal, higher self‑discharge, and noticeable voltage sag under load. That’s why the battery indicator will never be accurate, and the reported battery level reflects the chemistry more than the actual consumption of the sensor.
If alkaline cells lasted only about four months for you, that usually points to the device’s specific power profile or environmental conditions, not to any inherent advantage of rechargables.
In low‑power IoT devices, lithium AAA cells typically offer the longest and most stable operation (often 2–3 years), with far fewer voltage‑related issues.
The most likely reasons why alkaline batteries last only about four months are:
– weak signal and TX retries, which significantly increase energy usage;
– very frequent reporting intervals, especially for temperature or motion;
– low ambient temperature, which reduces alkaline capacity;
– low‑quality or old alkaline cells, which often have much lower real capacity;
– higher idle current caused by poor firmware or device behavior.
So yes - four months is possible, but it usually indicates an issue with the device or installation rather than normal battery consumption.
That’s right—my sensors that use AAA batteries are lasting an average of 2.5 years. They are door and temperature sensors; I think I have some motion ones, too! Personally, I think that kind of longevity is excellent! When I used rechargeable batteries, they barely lasted 6 months.
