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Topic: Power arduino with an external battery!!! (Read 921 times) previous topic - next topic

CrossRoads

Quote
If you hook any battery at all to the 5V pin, you'll never ever get a proper 5V on the 5V
buss of the board.


Why not? That pin IS the 5V bus on the card.  Whether that pin is supplied from the 5V regulator, the USB port, or directly from outside, the devices connected to it will not see a difference, and devices connected to IO pins will not see a difference.

I would put a 1N4001 diode from 5V (anode) to Vin (cathode), the currently used regulator NCP1117 is susceptible to damage from being reverse driven.

Zoomkat, sounds like you have a busted regulator.

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

oric_dan


Quote
If you hook any battery at all to the 5V pin, you'll never ever get a proper 5V on the 5V
buss of the board.


Why not? That pin IS the 5V bus on the card.  Whether that pin is supplied from the 5V regulator, the USB port, or directly from outside, the devices connected to it will not see a difference, and devices connected to IO pins will not see a difference.

I don't understand this comment. If you hook a battery directly to the 5V pin on the Power header,
how can you still expect to have 5V?

zoomkat

Quote
Zoomkat, sounds like you have a busted regulator.


I then powered the board with another 7805 connected to the arduino 5v pin and things then worked as expected. The arduino was an early ebay board, so the onboard 7805 could have been bad from the start.
Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

CrossRoads

"If you hook a battery directly to the 5V pin on the Power header, how can you still expect to have 5V? "
I see what you're saying.  I interpreted that as "any 5V source" and not so much a battery literally.

You can have a 5V, or nearly 5V battery, connected - such as 4 x 1.2V NuMH batteries, for ~4.8V.
Or a battery or two with a boost converter, such as
http://www.pololu.com/catalog/product/798
http://www.pololu.com/catalog/product/2119
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

retrolefty


I am using arduino uno. It has a port named as "Power". At that port there are pins available for 5v and GNG. So you can connect those pins to your external battery. I have tried it and it works fine.
Regards


And the current answer from the Arduino product people is:

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.


Of course this topic has been discussed so often in the past, to no satisfactory conclusion for all.

Lefty

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