TTGO Lora32 2.1 Charging

Development Hardware
1

I understand that power/battery state is wonky on the Lora32 boards, but the v2.1 specifically has a TP4054 charge controller that is programmable. Does the current firmware use it at all? Does it bypass the MCU entirely?

Can anyone explain how charging works on this board currently (no pun intended)? Does USB charging work with the power switch in either position? Any LED indication that charging is working?

Thanks

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2

So here’s what I managed to figured out after extended testing.

  • Red LED indicates USB power connected
  • Blue LED indicates battery charging
  • Charging only works when Power switch is in ON position, even though USB power will powerup the device with the switch in any position. Apparently the switch simply disconnects the battery from the entire board, including the charging circuit.
  • Firmware charge_current setting seems to have no effect, and the firmware doesn’t see batt voltage on this board either. I guess the charging circuit isn’t connected to the MCU.
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3

Hello,

Good point as i face a lot of Lithium battery failures after a few weeks (usually 4) on my testing installation which is on a tree on a solar panel providing USB-5V regulated power source on daytime…

i have the feeling that power management is not operationnal on this board,

hope we will find the solution :slight_smile:

on my side i add an extra low cost BMS on the batteries soldered directly on the 18650, and no more exhausted batteries

Best regards,
Fabrice

4

The lora32 v2.1 charge controller is programmable by swapping out a resistor. It’s not programmable by the firmware loaded on the CPU.

What I don’t see is a battery protection circuit. A protected battery or what @F4GXP did is right on.

5

With your BMS, will the device come back on by itself if low battery threshold is triggered, when the sun comes back up?

I use those little lithium charger-protection circuit boards but I have had trouble in the past because if the battery does go flat, the solar panel can’t supply enough current to boot the device so it stays in a half powered state with the battery offline.

Generally I can fix it by holding the reset button for a few seconds (so the battery can charge just a little bit), but that is annoying for relay nodes that live up the top of a hill.

I kinda get by by having overkill solar and battery so that it hopefully never goes flat. But I don’t like saying “hope” in a situation like this

6

The behaviour with BMS seems OK
=> No need to climb on the tree for 11 weeks and we have cloudy days :slight_smile:

just an additionnal information 2 x 18650 in parallel with 1 BMS (very thin one 1S 3A 3,7V 18650 BMS)
:battery: :battery: