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.

  • 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. – Peter Paul Kiefer Feb 10 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 at 13:16
  • Ignore the LED. Have you managed to establish communication with the SIM800L over the UART port? – Majenko Feb 10 at 14:27
  • I thought it needs power to start a communication. Okay let me try that. – sdebarun Feb 10 at 16:29

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.

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