I have to power my arduino and the GPRS shield with a 12v 7000mah battery but I am not sure how should I connect it.
The GPRS shield needs a 5v @ 2A but I don't know what about Arduino uno, does it needs something max 1A or I can give more than 1A?
What are the solution to convert 5v @ 2A and give power to Ardruino?
I found there is a converter 12v to 5v but it handle only 3A , the battery has 7000mah.
Sorry I am not good in electronics and I need some help to figure out this simple problem.
Because a battery is capable of a large current capacity doesn't mean that you have to use it. It's like a car... goes fast If you tell it to, not because you have to.
If your GPRS sheild requires 2 A that means that it draws 2 A or 10 watts of power which is .83 A at 12 volts so you might be able to operate for 7 hours with a switching regulator. The calculation is like this calculate the power in watts at the required voltage (2A X 5V = 10 watts... so we need 10 watts from the battery and a switcher is "About" so from the battery we need 10 watts + the efficiency (.8 - 1.0 X the required power is .2 watts) + 10 watts = 10.2 watts or .85A from the battery to supply 5V @ 2A. The .2 watts is lost as heat. With a linear regulator you would have a 2A load at 12 V or 24 watts from the battery and 24 - 10.2 = `13.8 Watts lost power in the linear regulator as heat. so with a linear you loose 57.5% of your power as heat... Not so verry good. The buck mode or step down switching regulators can be purchased for about $1.75 from Ebay and I would use 2 one for the 2 A load and one for the 1.2 A load (approx) for the Arduino. Amps is like gas tank capacity20 - 40 - 80 liters... but you only use what you need. Volts is like Octane if it's too high you go too fast and then you might crash and burn...
Doc
I should give you some information about my configuration:
What I want to confirm is that if I am going to attach the battery directly to the Arduino, does it works? I know that Arduino can handle 12 V but I don't know about 7'000mah, I think so that I understood that doesn't care if I have 1000mah o 7000mah, Arduino will take as much as it needs, right?
What about the regulator? If I buy a 12V to 5V at 3A, does it work with the battery? Does it work as I describe the Arduino that it will take max 3A ?
Sorry to be very stupid with all these questions but I want to make sure that I understand everything
max246:
I should give you some information about my configuration:
- The gprs shield needs 2A only sometimes, when I connect to the network, call and something else.
- The configuration with a normal power supply I can power all other items, temperature sensor, 2 servos and a camera.
What I want to confirm is that if I am going to attach the battery directly to the Arduino, does it works? I know that Arduino can handle 12 V but I don't know about 7'000mah, I think so that I understood that doesn't care if I have 1000mah o 7000mah, Arduino will take as much as it needs, right?
Correct, an arduino board will only consume about 80ma or less, not counting anything you might have wired up to the shield pins.
What about the regulator? If I buy a 12V to 5V at 3A, does it work with the battery? Does it work as I describe the Arduino that it will take max 3A ?
No, that is not required to just run the arduino board, 12vdc directly to the arduino external power connector is fine. However if you are going to also power things wired to the arduino such as servos or motors then an external regulator is often required to met the current and voltage demands of those devices. An arduino is very good at controlling external things, but does rather poorly at attempting to power external things.
Sorry to be very stupid with all these questions but I want to make sure that I understand everything
No stupid questions around here, unless you count the ones you don't know or forget to ask about.
Lefty
Ok thanks:)
So what I want to do is to connect the battery to the Arduino and then buy a regulator similar to http://www.1topstore.com/en-gbp/car-power-supply-dc-dc-regulator-converter-12v-to-5v-3a-15w-p21794.html and connect my GPRS shield on that + servo shield.
Does it make sense?
Battery[12V 7000mah] => Arduino
=> Regulator => 5v pin + ground and connect the ground to the Arduino board
5v pin + ground
This is the gprs shield: https://www.sparkfun.com/products/9607 and this one the servo shield that has the option to attach an external power source IO Expansion Shield for Arduino v5 (Discontinued) - DFRobot
Careful powering your Arduino through the +5v pin! I recommend reading this topic, and the links on this post:
I will not power my arduino through the 5v pin, I will use the normal jack connection and then I attach 5 volts to the gprs shield that the 5v pin will not connected to the Arduino.
