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The problem is, the specs of the LiPo Rider Pro claim it is able to provide up to 1A Max. However, the GSM shield needs 2A (in peaks time), in addition to the arduino power and the sensors (around 100 mA).

I tried powering up this system with a 2A powerbank but it didn't work, I powered it up with 12V, 2A adapter and it works fine! I couldn't understand why the powerbank is not able to power it up although the current in both is 2A.

I also tried connecting the GSM shield directly to the battery (which is 1C and should provide up to 10 A, but it also didn't work.

The main question is, how to power up the arduino with the GSM shield using the battery and the LiPo Rider, do I need to use a capacitor for short term power storage? Is there a way to boost the current? What is the best way to do this?

Here is a picture of my circuit:

enter image description here

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    \$\begingroup\$ Did you already try to put a couple of capacitor on the 5V on Arduino side? Try with some parallel capacitor, with a low ESR near the GSM module \$\endgroup\$
    – schisanoa
    Apr 27, 2017 at 12:22
  • \$\begingroup\$ actually I haven't tried adding capacitors, I tried to power up the shield with the battery directly which can provide up to 10 A but with 3.7 V but it didn't work. what capacitor value would it be appropriate ? \$\endgroup\$
    – Sabir Moglad
    May 2, 2017 at 4:43

4 Answers 4

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The key issue is that your GSM shield has its own on-board regulator (the huge 5-pin IC in the top right-hand corner of your photo) and requires VIN > 5V to provide a properly regulated 4.1V to the GSM module. Additionally, the Arduino itself requires Vin > 6V for proper operation.

An easy way to meet the above two requirements is to use two LiPo cells in series to supply 7.2V to the system's PWRIN ("9V") jack, as shown below:

Battery-Arduino-GSM-neonzeon

I'm not sure if your version of LiPoRider can be used to charge two cells in series. If not, find a charge control board that does.

You could also bust a few moves to improve battery life of your Arduino board.

As a side note, a GSM module that was switched off takes around 30s to connect to a base station - don't forget that in your battery life estimates.

Safety note: If you circumvent the PWRIN jack by connecting your LiPos directly to VIN and then plug an external power supply into to the PWRIN jack, you could start a LiPo fire.

Therefore, be safe and connect the LiPos to the Power jack. (or use VIN but put epoxy in the power jack/unsolder D1 to make the jack unusable) Connecting the LiPos to the PWRIN jack additionally gives you reverse battery protection due to diode D1 (see Arduino snippet below), but on the down side D1 drops a whole 1V while the GSM module transmits.

Arduino-PWR-IN-neonzeon Arduino Power Supply Schematic

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  • \$\begingroup\$ I liked your approach, how would this approach be compared to adding DC-DC step up converter that has input voltage of lets say 3.7V and (adjustable output voltage - 3A output ) ? \$\endgroup\$
    – Sabir Moglad
    May 3, 2017 at 4:03
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    \$\begingroup\$ Average Current = Standby Current + ( Duty Cycle x Active Current) This important equation tells you that in systems with low duty cycle, standby current is the key factor that determines battery life. Avoiding DC-DC boost regulators typically result in lower standby current and therefore longer battery life. \$\endgroup\$
    – neonzeon
    May 3, 2017 at 19:52
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The main problem is if your trying to run it off of 5V USB, the cable and regulators are going to add a lot of resistance and inductance which is going to slow down the sources (Lipo Rider) ability to source current immediately to your Arduino Mega board.

The lipo rider proabably doesn't have enough current to source even if you did

Here are some options:
1) Take some caps and solder them as close to the input or linear regulator on the Arduino Mega board. You didn't list your board, but I believe its the same as the one listed here. If your soldering on electrolytic capacitors pay attention to the polarity. This will negate the inductance of the USB cable by providing local storage. This may not work because the regulator might only source 500mA anyway (but this will depend on the flavor of board you have that you didn't list)

2) The Arduino Mega board has as MP2307 DC to DC regulator on it. Because of this it has a 7-12V (depending on where you bought it from) range on the J3 input. This will regulate the bus voltage on the Arduino Mega board to 5V with good efficiency. It would be better to use a step up DC to DC and use the 7V input on the Arduino Mega board. Stepping up voltage is a great way to get around resistance problems (power companies do it with HVDC lines)

3) You might be able to get away with the setup you have now if you had a really short USB or a cable that has a bigger gauge wire. The USB spec is 500mA, I believe there are nonstandard cables that will carry more current on the market.

4) If your into hacking, you could change the feedback resistors on the lipo rider's U1 DC to DC regulator which is a isl97516 PWM step up regulator and step it up to 7V (or more) (and not use the usb output of the Arduino) and wire that to the J3 input on the Arduino. Look up the voltage and change the feedback resistors on the board, it can go at least up to 12V.

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  • \$\begingroup\$ 1- I am using the main arduino Mega board, adding capacitors is great option yes as I am planning to power up the GSM shield via the VBAT pin directly, I haven't tried that but i thought there might be a more efficient better solution. 2: actually the power is a major concern of this project as I need to power it up remotely for some time, I believe adding this step up converter will add more power requirements ? 3: I believe this is why when I connected my 2A powerbank it didn't work because the USB 4: that would be a good option too if the rest options didn't work. \$\endgroup\$
    – Sabir Moglad
    May 2, 2017 at 5:44
  • \$\begingroup\$ With DC to DC converters, you won't take much of a hit even while stepping up the voltage. To do that kind of analysis however, you need to know the voltage and the currents of the regulators. DC's are usually 90%+ . If you had a meter, you could test the configurations and measure the current. Linear regulators are different however if you step up the voltage you waste the difference in voltage multiplied by the current. \$\endgroup\$
    – Voltage Spike ♦
    May 2, 2017 at 6:05
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Many GSM module datasheets call for a lot of capacitance to handle the transmit pulse current demands.

I would place 220 uF or more as close to the GSM module as possible. Obviously with correct design you can drive GSM with an even smaller LiPo cell but wires are short and the power circuits are designed with the current pulses in mind.

Your 1A output is not enough for the GSM module without some help. If the GSM module can handle 3.5 to 4.5V input you could possibly connect it directly to the battery but you would need to check the data sheet and possibly have to make wiring changes.

EDIT:
A SIMCom 900 datasheet indicates direct battery connection to the module of 3.4 to 4.5V so direct battery connection to a LiPo would be the best for avoiding the converter on the LiPo Rider in the radio supply path.

More EDIT:
I am suggesting bypassing all regulators between the SIM900 module and the LiPo cell the way it was designed to be used. That way the regulators cannot be blamed for not being able to pass the required current or have the required headroom.

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    \$\begingroup\$ Correct, but typical Arduino cellular shields have their own 4V regulator on board that require their own power source. (The black power jack in the photograph) You therefore need >6V (2V drop) to properly power the GSM shield. \$\endgroup\$
    – neonzeon
    May 2, 2017 at 22:10
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    \$\begingroup\$ adding a capacitor is definitively a good thing, this regulator answered why me trying to directly to connect the battery didn't work \$\endgroup\$
    – Sabir Moglad
    May 3, 2017 at 4:05
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years ago I built a similar circuit, with a sony ericsson custom gsm module and a rechargeable battery.

the main problems are the inrush current while the radio is transmitting ( max load ) and the output impedance of the battery

note that 2A can be average, not peak at full load

check carefully the specifications of the battery, radio module, and each voltage regulators ( also onboards)

and after ... don't trust the specs : measure the currents

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  • \$\begingroup\$ this is more like a comment not an answer but thank you for the useful tips \$\endgroup\$
    – Sabir Moglad
    May 3, 2017 at 3:56

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