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Alexandre Quessy
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Hi !
I just want to know what is the best battery setup for the Arduino BT. I want rechargeable batteries. The Arduino BT expects 5V pretty much... Should the ideal solution use a 7805 voltage regulator ? a DC-DC converter ? 9V batteries ? A very big 6V battery ?

My setup should be easily rechargeable using a DC power cable and a switch, for instance. It is for an art installation that uses a Arduino BT. The battery should be recharged every day, or so.

Thanks !
« Last Edit: August 14, 2008, 03:48:05 pm by aalex » Logged

Alexandre Quessy

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Hi Alexander,

The board itself does not take much energy. I use two AAA battery's and it works fine for about a day. To be sure you could use AA battery's instead if you have a lot of power consumption (when using a LCD screen for example it goes much farther then when you only measure sensors). What are you going to combine with the Arduino? I combine my switches with 10K resistors and I have 10K potmeters.

Hans.
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I used a 7.2v 1500 mah battery i got from hobby town usa. Which works great plus it has insanly long battery life and can power 2 servos and a ping sensor for a pretty long time. You could use some AAA batteries but just saying they wouldnt last long. Depends on what your using it for.
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Continuing....then just get a 5v regulator and you should be fine.
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robotkid249 - How do you recharge your batteries?  
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Related power question. My board has a 4 pin female header which reads/looks like:

   POWER
5V  Gnd  9V
 x   x   x   x

I've read the admonitions about not using too high a voltage or reversing polarity--so just want to be 100% sure this means I can use, for instance, a 9V battery to power the whole board. I've looked at the schematic for the board, which shows a VIN but doesn't specify a voltage. So, a related question for my general education is am I missing something on the schematic? Should I be able to definitively answer this question for myself?

Thanks!  
« Last Edit: August 28, 2008, 04:45:58 pm by bill » Logged

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It seems like recharging a battery is pretty straightforward. Just apply a DC voltage to the battery : plug +Vcc to Vcc, and GND to GND. We need a diode that makes sure the current only goes from the supply's +Vcc to the battery's +Vcc. That's it.

Now, I am currently looking at a 5V DC/DC converter to get 5V out of pretty much any voltage, it seems. With 2 AAA it should work. The Minty Boost from Lady Ada uses a LT1302. See http://www.ladyada.net/make/mintyboost/ and http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1031,C1060,P1029

Though, this setup wouldn't last very long. It is a very nice IC for a small circuit that doesn't use much current, or is not intended to last so long. Also, note that a 7805 5V voltage regulator does heat up when used with a voltage of 7V or more. A DC/DC shouldn't create heat. It think it also doesn't burns Amperes-hours, which makes it a better solution than a 7805.

a

a

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Quote
Related power question. My board has a 4 pin female header which reads/looks like:

   POWER
5V  Gnd  9V
 x   x   x   x

I've read the admonitions about not using too high a voltage or reversing polarity--so just want to be 100% sure this means I can use, for instance, a 9V battery to power the whole board. I've looked at the schematic for the board, which shows a VIN but doesn't specify a voltage. So, a related question for my general education is am I missing something on the schematic? Should I be able to definitively answer this question for myself?

Thanks!  

Plug the 9V battery in via the external power connector, that way it is regulated by the 7805 down to the required 5V.

You can sort of answer the question for yourself - the first component after the plug is the 7805 regulator, so the arduino board's input voltage range is defined by the allowable voltage range of the 7805 - and you can find this in it's datasheet.
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The best choice for type of battery would bu lythium polymer. They last a really long time even when using multple motors. You can get them at a hobby shop. They cost about 25 canadian for the battery and charger. Hope that helps
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Hi I am using a BT arduino just to send info to computer (with piezo contact mic)
Are 2AA also necesary or could i use something lighter like a lithium cell? I need to spare some
weight. thanx
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According to this page:

http://www.arduino.cc/en/Guide/ArduinoBT

the Arduino BT will run with an input as low as 1.2V. So, it could run from one AAA battery or from a Lithium cell.

That said, they may not last long.

Mike
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Quote
Quote
Related power question. My board has a 4 pin female header which reads/looks like:

   POWER
5V  Gnd  9V
 x   x   x   x

I've read the admonitions about not using too high a voltage or reversing polarity--so just want to be 100% sure this means I can use, for instance, a 9V battery to power the whole board. I've looked at the schematic for the board, which shows a VIN but doesn't specify a voltage. So, a related question for my general education is am I missing something on the schematic? Should I be able to definitively answer this question for myself?

Thanks!  

Plug the 9V battery in via the external power connector, that way it is regulated by the 7805 down to the required 5V.

You can sort of answer the question for yourself - the first component after the plug is the 7805 regulator, so the arduino board's input voltage range is defined by the allowable voltage range of the 7805 - and you can find this in it's datasheet.

Am I missing where the 7805 is? Here's a photo of the board:
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Am I missing where the 7805 is?

The Arduino BT uses a dc to dc converter (max1676) instead of a 7805 type voltage regulator used on most other Arduino boards
« Last Edit: September 21, 2008, 01:43:49 am by mem » Logged

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The Arduino BT uses a dc to dc converter (max1676) instead of a 7805 type voltage regulator used on most other Arduino boards
Since the max1676 steps up voltage, that makes it clear how the board can be powered with voltages well below 5V. Its not that I actually NEED to use a 9V battery, but really want to understand the limits of the stock board, and just how to power it correctly. Here's what I now think I understand: Looking at the photo I posted, I can power the board by putting a power supply that delivers between 1.2 and 5.5 Volts to the two post screw down terminal at the far lower left of the picture, with ground (-) to "2" and (+) to "1".

Where it says:

       POWER
 5V    Gnd    9V
  x     x   x    x

Is this terminal block just intended to power other components? I.e. the board should always get its input power from the posts marked "1" and "2" at the far lower left of the board? I'll probably burn things out if I actually connect 9V (+) to where it says "9V" [and (-) ground to one of the two "Gnd" terminals]. In fact, where it says "9V" that really just deliver the raw (+) input voltage that I input at terminal 1 at the far lower left of the board. At this same terminal block though, I can use the 5V to power other components that require 5V, since it will deliver the stepped up voltage from the max1676.  Is it fair to say I should just steer clear of the terminal with the 9V designation, and treat that label as an error? This 9V terminal only applies on a non BT board, where (+) 9V was delivered to the far left terminal "1"?

Again, I hate to seem dense--truly, just trying to learn a bit here...
« Last Edit: September 21, 2008, 11:40:35 am by bill » Logged

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