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dmitry-cherkas / esphome-danfoss-eco

Extend Danfoss Eco eTRV BLE range over WiFi with ESPHome.
MIT License
21 stars 11 forks source link

Battery % always wrong #23

Closed reinisb closed 3 months ago

reinisb commented 3 months ago

The reported battery % is always wrong. When I install brand new batteries, it shows 36% and then over days goes down to 25% and stays at that level. Any ideas?

Screenshot 2024-01-29 at 00 54 20
ckoca commented 3 months ago

You are probably using rechargable NiMH batteries. Those have a nominal voltage of 1.2V compared to alkaline batteries with 1.5V. That's why you are seeing a much lower battery charge percentage even at full charge. The discharge curve of NiMH batteries is much less steep than Alkaline batteries though, so you should be able to use them for a long time at about 25% charge.

nimh_vs_alkaline.gif

Image Source

reinisb commented 3 months ago

Ah, you are absolutely right, I did not think of NiMH causing this! Thanks a lot for the context.