Running a BMP sensor on Esphome with MQTT and fixed IP address on Wemos D1 Mini. Using a 18650 battery and solar panel with charging circuit. Very little sunlight the past month. Voltage across 18650 down to 3.15V today from 4.15 in September. Any tips to reduce draw on battery?
Don’t use “classic” WiFi but transfer the data with something like esp-now or with rf/Lora/… (need extra hardware).
For sure there is also much to improve. Do you know the “standby” current of your circuit?
Or you might just add more solar panels to “survive” the dark…
Another solution (might be the easieat and maybe even cheapest?) is to get a cheap ble thermo/hygrometer like this cheap (~$5) xiaomi/mija thingies and use a esp32 (plugged in to a wall socket) with esphome to get the readings into your network.
Box has limited space for solar panel. Could get a same size but better power. Perhaps a mono-crystaline panel. Considered removing LED on the wemos but never saw it light when tested before setting outside. Getting good wifi -54dB.
The Wemos may run off the 3V. The 3V is regulated. LDO for the 3V might waste just as much I worry. Battery Voltage goes up to 4.2V when fully charged so bit risky to connect directly to Wemos without regulator. Will reduce WIFI power down few milliwatts when take it in. Will adjust it to take fewer reading by increasing sleep time when battery lower. Looking for any ideas so thanks @orange-assistant
There’s the whole code. I agree it’s the standby draining most current but it may be the price of doing business on this hardware. I noticed when I updated HA the voltage would drop when HA came up again. Device may not have gone into deep sleep when MQTT offline.
… and check out the video tip of @orange-assistant above. That guy from Switzerland has released a bunch of really good videos about your subject (see YouTube). He measures and compares deep sleep current of several boards, identifies energy wasting components on the boards and removes them if possible. Really helpful.
Use fast connect on most of my ESP32s. Doesn’t work as well on this project due to placement of my WIFI access points, I suspect. Perhaps it has improved in recent versions of ESPhome. Will give it a try. Thanks for reminding me.
Early update. Even with just few hours weak sunlight over last 3 days the voltage seems to be on the way up.
[22:25:11][I][mqtt:214]: MQTT Connected!
[22:25:11][I][app:060]: setup() finished successfully!
[22:25:11][I][app:099]: ESPHome version 2021.11.1 compiled on Nov 25 2021, 22:14:52
[22:25:21][I][deep_sleep:072]: Beginning Deep Sleep
[22:34:52][I][mqtt:214]: MQTT Connected!
[22:34:52][I][app:060]: setup() finished successfully!
[22:34:52][I][app:099]: ESPHome version 2021.11.1 compiled on Nov 25 2021, 22:14:52
[22:34:52][I][deep_sleep:072]: Beginning Deep Sleep
You can see from esphome log the previous setting of run for 10 seconds then sleep. I turned on the automation to send mqtt message to wemos as provided on early sleep and then it turns of all in the same second. I’ve noticed that it still sometimes takes the 10 seconds. Max time possibly saved of runtime is 24 mins a day. Might just be enough saving on battery to get me through the winter.
I have sent off for a similar sized solar panel but monocrystaline which should have at least a 25% greater power to charge.
Have build a second battery powered espboard with temp and pressure sensor. The outside battery is still connected to solar panel but no sunshine in over a week. Slower reduction in voltage but it may be just because battery is around the 3.7v.
New esp12f is just a bare esp12F on adapter board with few pullup/down resistors and no capacitor across the vcc/ground. It is connected to 3.3v connection on the 18650 battery shield. I broke the charge usb port off the shield. Good smooth readings from the BMP280. Tried to connect outside battery to the wemos D1 by 3.3v but a lot of jitters in the temp graph and possible board restarts. Might try it again later with a capacitor across vcc/ground. Suspect it’s the wifi that causes the spikes in power upsetting the readings.
This is the circuit diagram for new weather station. The cost of doing business has gone down since I used the 3.3V output from the Battery shield regulator compared the 5V output. No jitter on the temp and pressure as seen when tried to run Wemos D1 mini from 3.3V.
Just one little hint:
The Wemos D1 mini already contains an internal voltage divider with 220k and 100k behind its A0 pin. If you want to increase the max input voltage you can do that with a single resistor in front of the A0 pin. This adds to the 220k resistor. In your case (4:1 divider for voltages up to 5V) you would simply put 180k in front of A0, so your resulting voltage divider would be (180k+220k) : 100k = 4 : 1.
With your circuit you will actually not get a 4:1 divider because the internal sum of 320k lies in parallel to your 110k and pulls it down more than you expected.
This board is running off the 5V.
The multiplication factor for wemos was 5.1817 to get peak voltage to 4.2V
and 4.8208 for ESP12F ( although this may have to be increased a little when I check it again).
Current draw should be very small to A0. Battery shield and voltage check is still probably biggest drain as @orange-assistant suggested , but I think this will be enough in these dark latitudes to carry me though a whole year. I have got the wifi output_power: 14dB and still getting good signal.