4 ms·

LILYGO® TTGO T-Energy (http://www.lilygo.cn/prod_view.aspx?TypeId=50033&Id=1170&FId=t3:50033:3 http://www.lilygo.cn/prod_view.aspx?TypeId=50033&Id=1170&FId...)

by w3p706 6y ago

LILYGO® TTGO T-Energy (http://www.lilygo.cn/prod_view.aspx?TypeId=50033&Id=1170&FId=t3:50033:3 http://www.lilygo.cn/prod_view.aspx?TypeId=50033&Id=1170&FId...) is my favorit. It has a 18650 battery holder and charging circuit. 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.

Rebelgecko 6y ago
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
- w3p706 6y ago
  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. Schematic is found here: https://github.com/LilyGO/LILYGO-T-Energy/blob/master/t18_v3.0.pdf https://github.com/LilyGO/LILYGO-T-Energy/blob/master/t18_v3... 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.

by w3p706 6y ago

Rebelgecko 6y ago

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

w3p706 6y ago
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. Schematic is found here: https://github.com/LilyGO/LILYGO-T-Energy/blob/master/t18_v3.0.pdf https://github.com/LilyGO/LILYGO-T-Energy/blob/master/t18_v3... 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.