Mind pointing me in the right direction? The ones I have are more like 10-20mA (maybe that's a side-effect of having USB on board? I'm not really an expert, I just want my battery powered stuff to last months instead of days)
With a BME 680, 2 seconds of measuring every 5 minute and esp-now protocol for sending, I estimate a 200+ day battery life. Esp-now protocol sends the message in a fracture of the time than wifi. Also you can tune the cpu & flash frequency depending on our workload. I have to wait 2s for the measurements to complete, so I lower the frequency to use less energy.
Just curious, have you been running it long enough to extrapolate that? I have some TTGO boards and they're a mixed bag. On one of the eink ones (which you'd think is the perfect scenario for deep sleep), they used a lipo chip that shuts everything off if the power draw is too low, so if you try to deep sleep the device never wakes back up
No, I did not, but I made tests with a configuration that was using more power.
I measured total runtime per wakup, and number of wakeups until the battery was depleted. I used this data to estimate the runtime if I take a measurment only every 5 minutes. This does not fully take in account the deepsleep current & battery self discharge. But wake up from deepsleep is definitly working.
From 3.7V to 2.7V I coud activate 37'000 times with a total runtime of about 8h.
You also have the battery voltage on IO35 with a 2x100kOhm Voltage divider.
The setup is not perfect, but good enough so far, and practical.
If I start over, i would look into
* taking a processor with lower speed und power.
* taking CR 123 or a battery optimized for very low self discharge current.
* Use a wireless protocol with very low overhead. I use ESP-Now now, WLAN would cut battery life in half.
That one has extra circuitry to shut the esp down completely and wake it on either an external trigger or RTC based alarm. It claims 1.5uA sleep current.
Thanks, these are some neat boards! A bit higher cost than the Aliexpress ESP32s I'm used to, but maybe that's the price you have to pay for better design and components. It's neat that the TinyPICO lets you turn off the power LED without having to cut traces on the PCB.
