12v + 2 ~ 2.5A

Hi all,

I'm using the Arduino Mega, 3 normal leds, GPS and Arduino GSM Shield.

I'm supplying this with the car cigarette lighter via VCC and GND (12v).

I imagine that it drains around 2 and 2.5A, but I would like to know if is ok or will burn the circuit?

What do you recommend ? When I use for long time I can feel the board a little bit warm.

Thank you

Hi, what are the specs of your GSM and GPS units, I think you will need a regulated 5V supply, the arduino will probably not have the current output for them, in fact the GSM probably at peaks needs 500mA. Check the info on your units first, do you have a multimeter and what electronics/programming experience do you have. What is the aim of your project?

Tom..... :)

Hey Tom
Thank you!

I had electronics at school long time ago, sorry if I make mistake.
The idea is to send position and temperature over the internet.

The GSM peaks are 2a and the GPS is 70mA at 4.5-6.5V (https://www.sparkfun.com/products/465).

Correct me if I’m wrong.

As I’m supplying with 12v via VCC, it means the 12v and the amps will drain independent of the how many amps arduino uses? Because the board connect the VCC to the GSM shield vcc, in other words, each shield will take a piece of the current?

I know that the ports of the arduino has a limit of 40mA, but is just to transfer data isn’t?

Hi, where are you getting the 5V supply for the GSM and GPS, I hope not the 5V pin on the arduino? Have you got a circuit of your project and how you have the units supplied. A pic of a hand drawn schematic and a pic of your project will help.

Tom.... :)

TomGeorge: Hi, where are you getting the 5V supply for the GSM and GPS, I hope not the 5V pin on the arduino?

I can see some more smoke escaping. :)

12V is rather high for powering the Arduino and means that the Arduino's voltage regulator has to dissipate a lot of heat to bring it down to 5V. If this 12V supply is coming from a car electrical system then it will be a very noisy supply which could also be significantly higher than 12V a lot of the time. It would be better to get a good 12V-5V converter with a smoothed, regulated output. These days they are inexpensive and small. Make sure the supply is rated to provide enough current to power the Arduino and any other devices you're driving from it. From the devices you've listed I would guess that a 1A supply would be sufficient, but check the specs and work out what the total current will be, and then add a 50% safety margin for the supply.