or the protection circuit failed or was not even there … but you cannot ever charge a lipo with more then 4.25 volts, could be a faillure in the dc/dc to
I used a Li-Po battery 3,7V / 840mAh. I then connected the board additionally to a 1A USB wallcharger
using it’s USB port.
If the power/charging circuit is designed similar to the Adafruit Huzzah32 then in this configuration the battery is being trickle charged (hopefully with a charge current <= 500mA) if you hooked it up via the JSTPH2 connector, and the board is using the power from the USB, right? Also the voltage measurement (on the voltage divider) is that of the USB power (not the battery) if the USB cable is connected; I also got that on the graph.
The only battery problems I have encountered was when connecting unprotected Lifepo4 batteries using the JSTPH2 connector and powering the board using the USB cable. Then the board tries to charge the battery up to 4.25V which is a problem if the LiFePO4 battery does not have a protection circuit. I lost a few batteries because of that (but none started to smoke).
Perhaps it was a short in the battery itself. I hope 
I can confirm. The TTGO V2 1.6 (T3_V1.6 20180606) goes down to approximately 8 mA current in deep sleep (measured with 4AA powering 5V via normal multi meter). It seems the OLED stays powered on while the ESP32 goes to sleep. Will try and see if powering down the OLED is possible (seems possible in the UG2 libraries, but this will take me some effort in rewriting my code from SSD1306 unfortunately).
Looking at the result achieved here: https://bengoncalves.wordpress.com/2015/10/01/oled-display-and-arduino-with-power-save-mode/ I hope to be able to bring the deep sleep power consumption down to less than <1mA.
You can put the SSD1306 to sleep when using the Adafruit library;
disp.ssd1306_command(SSD1306_DISPLAYOFF);
Takes less than 1uA in this mode.
Just tested using the adafruit library. Difference is very small. Power consumption only goes down to about 7mA. I wonder if the other peripherals can be put to sleep or shut down (e.g. RFM95 chip, SD card reader etc).
Make sure your SSD1306 is not the 5V type. The 3.3V ones do not have a regulator on the back.
I just received a warning from the TTGO (lilygo store) regarding their TTGO ESP32 Lora v2 1.6 with regards to charging LiPo’s via the 2.1 1.6 board.
Please all be careful. Message below:
Diode components should be used on the charging circuit.
We used a fuse. The diode is energized in one direction, but the fuse is bidirectional, which causing the USB voltage directly access to the battery.
After a long time charged, the battery is hot or burned, so please don’t use this V2.1-1.6 version to charge the battery! ! !
(Note: The board can be powered by battery, but we mustn’t charge the battery when the battery is connected to the board, mustn’t charge! mustn’t charge! mustn’t charge!)
If you want to use this V2.1-1.6 version to charge the battery, you need to replace the fuse in the picture with a diode, then the charging function return to be normal.
It can be changed the model number of the diode : BS5819 SOD123 / 1A current
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Hi
I just made an modified version of LMIC for ESP32.
It handle deep sleep between TX (by saving state to RTC RAM)
It use ESP AES functions and RTC clock.
If you are interested the code is here : https://github.com/ngraziano/lmicesp32
I test it on Heltec board in EU868.
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This seems to be a reaction to my post above, i forwarded it to Lilygo. That means my assumption battery has direct connection to 5V USB was validated by them.
Unfortunately another fatal design flaw and poor quality management seen at a chinese manufacturer…
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I received same mail today.
This is really dangerous. If i would have left the board with battery and USB connected unattended, my flat would probably had burned down. And i used a small 3Wh battery only. That’s far less than e.g. a common 18650 cell…
I’ve designed a small snap fit case for the ttgo V2 1.6. Some rough edges that I will clean tomorrow and then I’ll put it on thingiverse.
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good afternoon , i am trying to go down the ttgo v1 consume … in this moment i am in 8.7 ma ; i remove the leds license plate and the battery charger … someone Has anyone been able to lower this consumption?
It won’t be possible because of the board design. See this post on github and the entire thread for more information about this:
They are talking about the Heltec version, but the same principle should apply to the TTGO.
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hi, in this moment i have a ttgo in 800 uA, i want to get down more; but the flash memory isn’t in sleep mode.
Thanks
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How have you come to that power consumption? Very interested!
I’ve also got the TTGO ESP32 V2 1.6 unfortunately still can’t see the design on Thingiverse. Can you check if you’ve published publicly?
If you now following the link, you got the view off a nice case.
Be careful with connecting a battery, did you see the warnings above?
In the TTGO v1.6 design power from USB and battery runs over a diode (at least it should, when the did not accidently used a fuse). That means that we give about 0,1 Watt of power at this early point in heat, even before it arrives at any circuit… 
Hi all,
Been trying to use a 18650 rechargeable lithium ion battery with my TTGO ESP32 SX1276 microcontroller and not having much luck. TTGO does not seem to want to be powered by the battery.
From my understanding I thought that if you plug in the TTGO via micro USB it simply charged the battery and you are good to go, but it doesn’t seem to be the case with my testing.
Has anyone had any experience with powering this board using a battery? If so, could you please tell me what you had to do to get it working.
Thanks in advance.
Attached below are photos showing my setup for reference:
