Full battery test timeline for my Heltec board

[newtocrypto]

Full battery test timeline:

2145 25DEC - Orange light went out after a few hours indicating a fully charged battery. With the USB still connected the battery read 40% charged 3.65v on the screen, I did not test from the back of the terminal.

2150 - USB disconnected the battery read 38% charged 3.63v on the screen, and from the back of the terminal it read 4.13v

2151 - Battery disconnected separated from the device it read 4.13v

2152 - Plugged battery back in and left it alone

0945 26 DEC - I sent the device message #1 to wake it up, message received. On battery power only it read 5% charged 3.32v on the screen, and from the back of the terminal it read 3.82v

1045 - I sent the device message #2 to wake it up, message received. On battery power only it read 2% charged 3.28v on the screen, and from the back of the terminal it read 3.80v

1145 - I sent the device message #3 to wake it up, message received. On battery power only it read 0% charged 3.25v on the screen, and from the back of the terminal it reads 3.70v

1250 - I sent the device message #4 to wake it up, message NOT received.
I tapped the top button and the device woke up, the uptime timer had started over, I sent message #5 and it was received.
On battery power only it read 3% charged 3.25v on the screen and then died after a minute or so.
Maybe this part I did wrong but I was only able to get 0.91v from the back of the terminal.
I disconnected the battery and it read 3.79v

Using a 1000 mAh battery and stock settings for 1.2.45 beta firmware on a Heltec v2.1 board

My discord is @anchormetals and I was asked to put this here by one of the community members, hopefully, I did it correctly.

Edit: Expected behavior is that the battery would read 100% with the battery indicator full and for the device to last longer than 15/16 hours. I will be doing the same test with a 3000 mAh battery when I get one.

The battery indicator never read full and seemed to be consistent with what the device was reading on the percent side.

[jaykayenn]

More info on forum thread: https://meshtastic.discourse.group/t/heltec-esp32-only-charging-to-40-at-3-65v/4515

[newtocrypto]

OK, so I looked at the link @jaykayenn sent...

I used the 3.70 firmware from the link, my math went like this…
Charged battery from the terminal read 4.15v and one the screen 3.63v
3.63 / 3.2 = 1.134375
4.15 / 1.134375 = 3.658
I rounded my 3.658 up to 3.7 and if I used 4.2 for the terminal it would have come out to 3.702

26 DEC - I updated the new firmware, orange light comes on, and the battery starts to charge.
With the USB still connected the battery cycles between 0% + U at 4.23v and 100% at 4.20v on the screen, I did not test the back of the terminal. The battery indicator also cycles between a weird double line symbol and full.

2050 - Orange light went out, indicating charging complete, and with the USB still connected the battery cycled between 0% + U at 4.23v and 100% at 4.20v on the screen, I did not test the back of the terminal. The battery indicator also cycles between a weird double line symbol and full.

2100 - USB disconnected and on battery power only it read 99% charged at 4.19v on the screen, and from the back of the terminal it read 4.15v, with the battery indicator is full

0900 27 DEC – Woke up the device manually. On battery power only it read 66% charged at 3.86v on the screen, and from the back of the terminal it read 3.85v

2100 - Woke up the device manually. On battery power only it read 20% charged 3.48v on the screen, and from the back of the terminal it read 3.48v

2240 - Woke up the device manually. On battery power only it read 12% charged 3.38v on the screen, and from the back of the terminal it read 3.39v

0015 28 DEC - Woke up the device manually. On battery power only it fluctuated between 6%, 8%, 15% charged and 3.32v, 3.35v, 3.36v on the screen, and from the back of the terminal it read 3.35v
Seemed once the battery got low it wasn’t sure where it wanted to be…

0200 – Device did NOT wake up and battery read 3.2v from the back of the terminal

Way better outcome than before, the device lasted about 28-29 hours on a single charge with a 1000 mAh.

Hope this helps, don’t hesitate to reach out if you have any questions.

[jaykayenn]

This applies to TLora32 v2.1-1.6 as well, same vbat discrepancy between firmware and actual battery.

[tropho23]

I have two Heltec LoRa32 v2.1 boards and have the same issue. I'm using 3,000mAh LiPo MakerFocus batteries but the issue remains and I don't ever see more than 52% charge noted on the screen for one Heltec, and no more than 53% on the other. This is after the red battery charge LED on the board has gone out, indicating the battery is fully charged.

I have not done a runtime test but presume runtime would be 2.5-3x newtocrypto's results using a 1,000mAh battery.

[mchisari]

I confirm, when the orange light turns off the display shows 4.0V. Maybe some adjusting to voltage formula could fix?

[garthvh]

Closing will track extensive Heltec battery research / issues on #769

[geeksville]

This issue has been mentioned on Meshtastic. There might be relevant details there:

https://meshtastic.discourse.group/t/how-to-pair-headless-ttgo-lora32-no-display/3296/15

[newtocrypto]

I upgraded my Heltec v2.1 boards to firmware-1.2.54.288f2be and the battery issue seems to be fixed with this update...

The battery indicator reads full with a 4.2v reading on the battery and on the screen.

EDIT...
I have noticed on my boards that after a full charge (the orange light goes out) and I unplug them, the battery indicator still reads as charging with the +U thing by the percent of the battery charge and the display stays on. After a while, time varies per device, the screen will go out and when I wake it, it will read fully charged on the battery indicator and 100% for the battery charge.

[geeksville]

This issue has been mentioned on Meshtastic. There might be relevant details there:

https://meshtastic.discourse.group/t/who-is-interested-in-a-solar-light-relay-node/5495/29