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[on:]

Hi everyone,

I am new to Arduino. Please bear with me as I check for feasibility of the project. I have the following questions to evaluate (sorry I can't give the overall story yet as it has to stay under wrap until product is in demo)

1- What GSM modules are available that support SMS + Arduino NANO? (if they can do DATA it would be a bonus)
2- I would like to power the board and modules with AA batteries. What add-ons or modules do I need to use AA batteries to power the unit?
3- Wouldn't it be better for me to look into cellphone alternatives that would connect to Arduino Nano rather than a GSM module?

***I need advice to lower the price of this hacked product to as low as possible.

Thanks

[Reply #1 on:]

How long do you want the batteries to last.
Its feasable to do , but the battery life will be pretty short, less than 2 hours at best.

[Reply #2 on:]

Hmmm...that's not nice. I would like this to last for 6 months. Is Arduino not the right board for me? I thought there were other projects that use 4 AA batteries, a motor, and wifi module and it all can last 6-12 month on AA batteries.

[Reply #3 on:]

 Are you wanting a GSM module or a wi fi module.
They arnt the same thing.
In your original post you mentioned a GSM module.
Even an Arduino by itself wont run for 6 months on AA batteries,even in sleep mode as
The USB chip alone pulls around 15 ma ,which for AA batteries of 2500 maH will last around 7 days.
The GSM modules are the problem , power wise to run off AA batteries.
Heres the specs for a typical GSM Arduino shield.
http://www.sparkfun.com/datasheets/CellularShield/SM5100B%20Datasheet.pdf

Idles at 7 ma , on Transmit consumption anywhere from 300 ma up to 3000 ma.

[Reply #4 on:]

Mauried - Thanks a lot for the feedback.

I need GSM module. What I said was that "I thought there were OTHER projects with wifi...." that lasted very long.

Can you please explain how AA batteries work in mAh? Was your calculation based on 1 AA battery or it doesn't make a difference even if there were 4 AA batteries?

thanks

[Reply #5 on:]

A typical AA battery is around 2500 mah , and the battery voltage is 1.2 V if its a rechargeable
or 1.5 V if its a primary battery.
To run an Arduino you need either 5V regulated , or higher if you want to use the onboard regulator
on the Arduino board.
So you need at least 4 1.5 V AA batteries in series , or 5 1.2 V in series.
Even thats a bit marginal for the onboard voltage regulator.
With batteries in series , the same current flows through them all, so the mah capacity of the series
batteries is the same as one of them .

[Reply #6 on:]

To run an Arduino you need either 5V regulated , or higher if you want to use the onboard regulator
on the Arduino board.
So you need at least 4 1.5 V AA batteries in series , or 5 1.2 V in series.
Even thats a bit marginal for the onboard voltage regulator.

Maurid - Thanks again for the input. I have few other questions related based on your feedback:
1- Would I not be in a better position to use a 9V battery then than AAs?
2- I assume that regulated needs extra equipment and I want to stay from that. Does the onboard regulator allow a 9v battery to connect to it or any other battery like AA to connect to directly with a simple wire?
3- I assume I am better off with a Lithium-ion battery of all options above. If so, what type of Lipo battery best works with Arduino?
4- How would my situation be different if I were to use an Arduino Nano?

Thanks,

[Reply #7 on:]

If you mean the little rectangular 9V batteries, they have very low capacity, around 200 mah
so wont last very long.
LIPO batteries are much better capacity wise, but the cells are 3.7 V so you need 2 in series
to power an Arduino.
But LIPO batteries need a special  balance charger if you are charging 2 or more at the same time.
With any kind of project that has a Radio Transmitter in it , as the Transmitter generally is what pulls most of the
power, its important to know just how much of the total time the Transmitter will be on.

[Reply #8 on:]

Thanks for the info.

Would my situation be any different if I were to use Arduino Nano?
Also, I am looking to buy a kit or maybe separate parts. What parts do you suggest I should to get me started on some testing/playing with Arduino?

Thanks

[Reply #9 on:]

No, running any kind of Arduino off AA batteries is generally a bad idea unless you
can take some kind of drastic power reduction type strategies such as sleeping the Micro,
or you are happy to frequently replace the batteries.
This reduces the power consumption whilst the Micro sleeps, but it also cant do anything
whilst it sleeps, apart from wakeup on specific conditions.
But this doesnt help if you are using a GSM module which draws power all the time.
Basically, you need to figure out how often the GSM module will be transmitting, as thats
the big power consumer, and that will determine the battery life.

[Reply #10 on:]

One clarification here. An Arduino can run at 3.3V or 5V. It does not have to have 5V. Therefore a single LiPo will run the Arduino. It is even better if you can source your peripherals to use 3.3V as well. This is becoming much more common and it should be no problem finding what you want in a 3.3V variant.