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Topic: Mega Power source (Read 1 time) previous topic - next topic

he3r0

I have Arduino Mega 2560, and few of the 12V baateries like this


Can i connect it directly to the power socket on the mega? or do i have to add something else in between?
--
HE3r0
d(R)ive safe

retrolefty

Yes that can be plugged directly into the external DC power connector on the mega board.

Lefty

Jantje


Yes that can be plugged directly into the external DC power connector on the mega board.

Lefty

Even though this is true I would add a note based on personal experience.
The recommended voltage for Arduino Mega is 7-12V. A fully charged Lead acid battery holds 14.4V.
The input voltage limits are 6-20V.
This is not taking into account additional hardware attached to your arduino. So if you just have a mega running to see the led flash you are 200% OK. If you add an ethernet shield and some motorshields you may run into troubles.

In other words. Yes you can run from a 12 volt led acid battery. But when you have lots of power consuming shields or power consuming additional electronics the Mega may get overheated. In this case make sure your mega gets enough cooling (no closed box or walls around the mega, have it ly down on its long side, use a ventilator) or better use a switching regulator and power with a modified USB cable. The last option will make your solution run 2 times longer.
Note that it is the power converter on the board that gets (to?) hot. 

Practically. Use the battery and have a feel from time to time to verify whether your power consumption is sustainable.

Best regards
Jantje
Do not PM me a question unless you are prepared to pay for consultancy.
Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -

he3r0

Awesome, thank you guys for answers.
At This stage My projects Don't go further than simple LCD with ethernet Shield, and perhaps Some servos.  But im having feeling that Separate Circuit for 5v and 3.3v from battery To devices mighg Be a good idea. So i'll look Into that as well.
Once more, thank you guys.
--
HE3r0
d(R)ive safe

MAS3

If you're thinking about a mobile setup with motors, have a look at BEC speedcontrollers as used in RC models.
These often have a regulated power output to the RC receiver, and if i remember correctly, these are supposed to be at 4,8 or 6 volts.
Might be worth to have a look at these.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

Zapro


If you're thinking about a mobile setup with motors, have a look at BEC speedcontrollers as used in RC models.
These often have a regulated power output to the RC receiver, and if i remember correctly, these are supposed to be at 4,8 or 6 volts.
Might be worth to have a look at these.


Why use a ESC with BEC to power the 'Duino when OP does not need to use a brushless motor ?

You can get standalone BEC's

To OP: I would recommend a board like this anytime when powering the 'Duino from a voltage higher than 5,5V

http://goo.gl/xnJJz

Much more effecient, no extra heat!

// Per.

retrolefty

Quote
To OP: I would recommend a board like this anytime when powering the 'Duino from a voltage higher than 5,5V

http://goo.gl/xnJJz

Much more effecient, no extra heat!

// Per.


I'm a big fan of those Asian switching regulators, they are so useful and would be perfect for using 12v battery power with the switching regulator adjusted to 7.5 vdc output. I found them even cheaper (free shipping!) and bought five of them:

http://www.ebay.com/itm/251066005460?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Lefty

lemming

Quote
http://goo.gl/xnJJz


I like the line halfway down the page where it says:

"Maybe it like this? only ?5.72 ?kick the picture?"

Zapro


Quote
To OP: I would recommend a board like this anytime when powering the 'Duino from a voltage higher than 5,5V

http://goo.gl/xnJJz

Much more effecient, no extra heat!

// Per.


I'm a big fan of those Asian switching regulators, they are so useful and would be perfect for using 12v battery power with the switching regulator adjusted to 7.5 vdc output. I found them even cheaper (free shipping!) and bought five of them:


And why would you adjust them for 7,5V and burn off extra power in the Voltage regulator ? Why no set it to 5V and power the Arduino from the 5V-pin... ?

// Per.

zoomkat

Be advised when using the external power regulator with a higher external voltage to check the actual voltage on the arduino 5v pin.
Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

retrolefty

#10
Jan 06, 2013, 04:43 am Last Edit: Jan 06, 2013, 05:25 am by retrolefty Reason: 1


Quote
To OP: I would recommend a board like this anytime when powering the 'Duino from a voltage higher than 5,5V

http://goo.gl/xnJJz

Much more effecient, no extra heat!

// Per.


I'm a big fan of those Asian switching regulators, they are so useful and would be perfect for using 12v battery power with the switching regulator adjusted to 7.5 vdc output. I found them even cheaper (free shipping!) and bought five of them:


And why would you adjust them for 7,5V and burn off extra power in the Voltage regulator ? Why no set it to 5V and power the Arduino from the 5V-pin... ?

// Per.


Because the arduino folks advice against wiring +5vdc into the 5V pin.

Quote
5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.


Lefty

cr0sh


Because the arduino folks advice against wiring +5vdc into the 5V pin.


Provided the voltage supplied to the 5V pin is a well-regulated 5 volts DC (by whatever means) - there shouldn't be any problem.
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

retrolefty

#12
Jan 06, 2013, 10:57 am Last Edit: Jan 06, 2013, 11:01 am by retrolefty Reason: 1


Because the arduino folks advice against wiring +5vdc into the 5V pin.


Provided the voltage supplied to the 5V pin is a well-regulated 5 volts DC (by whatever means) - there shouldn't be any problem.


Then why the explicit warning on the arduino Uno product page? The older arduino Duemilanove that most of us started with did explicity state that one COULD do this. The latest Uno product page explicity recommends NOT doing it. CrossRoads thinks it's the change of +5vdc regulator device in the Uno that doesn't like or sensitive to having voltage applied it's output terminal while it has no voltage on it's input terminal.

Anyway here is the pin 5V definition in the Duemilanove product description:

Quote
5V. The regulated power supply used to power the microcontroller and other components on the board. This can come either from VIN via an on-board regulator, or be supplied by USB or another regulated 5V supply.


Here is the pin 5V definition in the latest Uno product description:

Quote
5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.


So don't be too quick to dismiss this issue. We may not have a definitive answer or explanation yet (or ever) but I for one when wanting to power an arduino board with external regulated +5vdc, go through the USB connector rather then the 5V pin, as that is how the Uno is operating when it's on USB power only, however don't dare ask me how that is any different electrically from the perspective of the on-board +5 volt regulator because I don't see a difference.   :D

Lefty

Zapro

Every sensible design with a linear voltage regulator has a diode wired from the output to the input, if this is not the case on the 'Duino Mega, one should add a 1n4148 and there is no problems.

Usually you only run into the problem if you have a large cap at the secondary of the Vreg (1000 uF or more) or some kind of H-bridge with a motor attached that acts like a generator if it's running and the power is cut. There is very little possibility of destroying the Vreg from "Normal" use of an Ardunio.

I power my Uno's and Mega's from the 5V connection all the time, never had a problem. There are literaly thousands of 3D printers out there with their Mega powered from the 5V pin, never a problem.

// Per.

retrolefty

#14
Jan 06, 2013, 11:10 am Last Edit: Jan 06, 2013, 11:14 am by retrolefty Reason: 1

Every sensible design with a linear voltage regulator has a diode wired from the output to the input, if this is not the case on the 'Duino Mega, one should add a 1n4148 and there is no problems.

There is no such diode across the on-board 5vdc regulator on any of the arduino boards ever released to the best of my knowledge and memory of reading the various schematics. CrossRoads thinks that is also the correct 'solution'. But alas that doesn't help newcomers to the arduino world with there brand new Uno board.

Usually you only run into the problem if you have a large cap at the secondary of the Vreg (1000 uF or more) or some kind of H-bridge with a motor attached that acts like a generator if it's running and the power is cut. There is very little possibility of destroying the Vreg from "Normal" use of an Ardunio.

I power my Uno's and Mega's from the 5V connection all the time, never had a problem. There are literaly thousands of 3D printers out there with their Mega powered from the 5V pin, never a problem.

Yes we know that, but have not received an explanation from the arduino designers on why they now explicitly recommend not to power the board via the 5V pin on the current Uno and Mega boards. Do you know why they added that caution? As I showed it was a added change from their prior definition for the 5V pin on both prior 328p based boards and the mega boards. The changed words didn't happen by accident I suspect?
Lefty


// Per.

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