Most efficient power source?

Hi, There are so many ways to get this done that this is a case where the experience of the community can bring light to decide the best way to go. I am working on a device that in few words, it is an Arduino Duemillanove controlling some buttons of a cellphone (on/off etc). The idea is that it should be a stand alone device with an autonomy of at least a week. Actually it drains about 480mAh. I cannot use solar panels... but a deep cycling battery (12VDC/100A) should be enough energy.

The main question: what is the best way to use it?

In detail: Arduino can be connected to that high amps battery using its regulated port? I know it can deal with the 12VDC but what about the amps? and since the cellphone uses 3.7VCD but itcan deal with 5VCD

we have three main options:

1) to go from 12 to 5VCD, without using the arduino's regulator using something like http://www.adafruit.com/index.php?main_page=product_info&cPath=38&products_id=184 is this possible? I guess it is not the best since it may mean to waste the 12-5=4VCD resulting not that efficient.

2) to go from lower VCD to higher. so like http://www.adafruit.com/index.php?main_page=product_info&products_id=14 or http://www.instructables.com/id/The_Arduino_AA_Undershield This of course would not include the battery described before but a large number of arrays of three AA batteries to get the amps needed or the newest type of ultra-capacitors.

3) using directly the 12 VCD/100aH battery to the regulated plug on Arduino and somehow o make arduino to deliver 5vcd to the cellphone?

do you know if these options are suitable to work on this high amps setting?

so, based on your experience, what do you think about this challenge; which would be the most efficient path, Option 1, 2 or 3? do you have a better idea? thanks!!! gps

Most efficient is a little interesting of a statement.

What I personally would do in this case (Since the cell phone is 5V tolerant) is run your own power supply to regulate the 12V down to 5V for both The Arduino and the Cell phone.

Any 7805 based power supply can be hacked for this purpose, but instead of installing the 7805, use this guy: http://www.hvwtech.com/products_view.asp?ProductID=585

Yet another valid way would be to give the Arduino the 12V and let it regulate it using the existing Onboard and the separate power supply just for your cell phone. In that case just sub the above regulator with this one and dial in the 3.7V you were looking for: http://www.hvwtech.com/products_view.asp?ProductID=586

Hi Brutus, thanks a lot. This is just what I was looking for. The first option you gave is great since 1amp is twice what I need to feed all the device. And with over 80% of efficiency, a car/boat battery of 100A should do the job for a week.
Thanks a lot!
gps :slight_smile:

If you live in the U.S., there are cheaper sources for that regulator, including buying direct from the maker.

There's also a lower-cost competitor, without the cute enclosure. Has anyone tried it? It looks well-made in the picture, but I've never actually used one.

Ran

Hi Ran, I only wish to have seen your message beforeā€¦ with the fedex shipping etc I had paid more than for the price of three or four units of your dealersā€¦
Thanks a lot. I am sure this will help me and others too.
gps

Sorry.. I should have mentioned you can get them everywhere.

The link I gave is local to me ;)