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I am using a SIM800L Module with esp32. I am using a 3.7V 2800mAh lipo battery to power the sim800L but the LED is not blinking. I am lookng for answers in web but evryone seems to have a different problem than mine. In other case the sim800l is at least blinkng or blinked once. I have tested the led with multimeter and it glows so hopefully the board is okay. Is the power supplied by the battery is not sufficient? I followed this tutorial

I am sure about the sim card as it is a working sim card in INDIA (of IDEA) and works fine in my smart phone.

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  • According to the linked tutorial, the power source is OK. Did you see the warning that, the GND must be connect before any other pin (especially the VCC). Otherwise the device could be destroyed. A working LED is no guaranty that the board is OK too. Most probably you destroyed the device or you made a mistake when connecting the device or the batteries lifetime is at its end or the battery is not fully loaded. You did not add a picture of your setup, so I can not help further with an eventually false connected setup. Feb 10 '20 at 11:20
  • okay I shall add the picture once I am home but just give me an idea of how to check the battery. While I check the voltage with multimeter I get 3.8V steady. If the battery is not fully charged then shouldn't it drop the voltage?
    – sdebarun
    Feb 10 '20 at 13:16
  • Ignore the LED. Have you managed to establish communication with the SIM800L over the UART port?
    – Majenko
    Feb 10 '20 at 14:27
  • I thought it needs power to start a communication. Okay let me try that.
    – sdebarun
    Feb 10 '20 at 16:29
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Can you please explain this part again? if possible,upload image!

As a solution what I did was, cut the legs of some quarter watt resistance and solder them to the wire exiting from the battery and fed them directly to the vcc and ground of the module. This way it works perfectly fine

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  • Hi @Patel and welcome to the Arduino Stack Exchange. This answer is unclear and needs clarification.
    – sa_leinad
    Jan 1 at 10:51
  • @Patel Let me edit my answer. This would help in a better way. and sorry for the delay, was busy with covid.
    – sdebarun
    Feb 26 at 18:20
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So I Finally sort out the problem. Both Battery and Module was completely fine. The problem was with the connecting wires. The connecting wires for some reason was not capable to hold the 2amp current. As a solution what I did was, cut the legs of some quarter watt resistance and solder them to the wire exiting from the battery and fed them directly to the vcc and ground of the module. This way it works perfectly fine.

Even it seems a weird problem with no proper explanation but this solution works for me.

-----------Editing for a better explanation-------------

So my problem was with the connecting wires. For some reason the wires I primarily used could not deliver the the current from battery terminals to the module. May be those wires had a higher resistance for which the current flowing through those could not stay at 2 ampere magnitude and by the time it traveerses the wires and reached to the module, it was no longer at 2 ampere and might be lesser than a certain value which could not trigger the module and so the module did not work.

what I did was cut some legs of a few quatter watt resistance (the metal leads getting out from the carbon resistance from both sides:pic added) and sholder them to the battery terminals. Since I knew the metal legs of quatter watt resistances had a very less resistance from my course that trick worked and delivered 2amp current through them to the module.

I am trully sorry for not attaching picture as I have already submitted the project and currently have no way to replicate the situation.

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