SIM800L external supply issue

Question

I have built an Arduino project that sends data from sensors to a specific website using the SIM800L GSM module. My problem is when I power whole circuit it from a computer or a charger, it works fine.

However, I want to use a portable power supply to run the circuit. But, when I use a battery, it does not work. SIM800L draws 2A current while transferring data. I used a 470 µF capacitor connected to the +VCC and GND pins of SIM800L.

I do not have any problems when I power it from a computer's USB port or a phone's charger. But when I connect a battery, SIM800L works at the beginning but then resets itself during transmission (probably due to not being able to draw 2A from the battery).

I tried to power SIM800L from battery and Arduino from computer it also didn’t worked, I think the current I get from the batteries is not enough to provide the current required for SIM800L's data transfer. I also did same with a powerbank but it also didn’t worked.

My aim is this circuit will work for 15 days and SIM800L will send data in every 10 mins or 15 mins. Circuit works well when I supply from computer or charger(for mobile phones), and not works when I supply from batteries and powerbank.

How can I solve this problem?

Components:

• Arduino Leonardo Clone
• Sim800L
• 470 µF Capacitor
• DHT11
• 3.7V Battery (2 in series)

I can provide simple schematic if necessary. When I supply from computer USB port Vcc of SIM800L is connected to 5V pin of Arduino, and Vcc pin of DHT11 is always connected to 3.3V pin of Arduino. If I supply SIM800L from battery or powerbank, then Vcc of Sim800L has connected to + side of battery. And for GND of SIM800L I tried two different way. One is barely connect GND of it to – side of battery. And other way is GND of Arduino, GND of SIM800L and – side of battery has connected together. But Arduino supplied by computer and SIM800L from battery.

I can provide more information if there will be request.

How to make a SIM800L work with external batteries on the street? What kind of battery should I use? I tried simple 3.7V batteries and powerbanks but it does not work. And it works when I power it up from a computer. How I can get same results as when power is supplied from a computer with batteries?

Answer 1

Had the same issue, solution was 1000 uF cap and short wires, yes too long wires were actually the issue for me.

Also optimal voltage for sim800l is 4 V with min 3.4 V and max 4.4 V, anything more can damage it.

I used generic 18650 to power it, even at ~3.5 V it worked well.

Answer 2

I solved the issue with using DC-DC buck converter and 1000uF capacitor. I had connected two 18650 3.7V batteries series to buck converter and adjusted to output voltage around 4.5 V (It is not always stable while working, there is drops on voltage time to time.) and connected buckconverter's output terminals to 1000uF capacitor and made parallel connection to supply pins of sim800l. Also tried to use short cables as much possible. And for cables related with supply I soldered them instead of using breadboard. Also in my case I am using Arduino Leonardo clon, for being able to use serial communication between arduino and sim800l I connected there GND pins to each other. If needed I can provide a humble circuit schematic. Thanks for everyone who gave advice and help.