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Topic: Arduino is fine when connected to computer but not when on battery (Read 2175 times) previous topic - next topic

Ashleysmith

As title,

When the external battery (9v) is connected the controller doesn't function and the servo goes to the right... However when it's connected to the computer directly everything works fine

Dan_ce

Too much current draw for the battery to cope with but the computer is able to? Get a wall adaptor?

Techone

The 9 V battery is too weak. ( current wise ). Try a wall AC adapter rated about 9 V at 500 mA at least and see what happen.

Ashleysmith

Tried that earlier and a similar thing happened but it wasn't as bad, my friend has a similar set up and his works fine

Dan_ce


Tried that earlier and a similar thing happened but it wasn't as bad, my friend has a similar set up and his works fine


Similar isn't the same as the same, though, right?

Is it a new battery?


retrolefty


true, yes its a brand new battery


Well you are fighting the same fight as so many other beginners do when first start trying to use servos. They require an independent DC power source of correct voltage (4.5 to 6vdc) at a current capacity of at least one amp for each servo to be used and this source cannot be reliably supplied from a arduino directly. Some do run one servo OK, if it's a small enough servom from the arduino +5v pin, but it's not a reliable was to power servos.

Techone

What retrolefty is saying, use two battery. 9 V for the Ardiuno board, and another battery of 4.5 V to 6 V pack for the servo motor. Connect the negative of the battery pack to the Ardiuno gnd, and the plus side to the red wire ( positive )  of the servo.

That might work.

Ashleysmith

thats the set up i have,

9v into the board and 4.5v connected to the servos...

my problem is, that when i have everything connected to the computer it works fine, but when i run it from the 9v battery it doesnt like it

Techone

Now, I am lost... 9 V is too week.  Did you have a picture of your setup ( how it is wired ) ?  I would like to see the situation.

Ashleysmith

this is it running off the computer

http://www.youtube.com/watch?v=68BHYHL9yVw&context=C3ff1949ADOEgsToPDskJ_cmEMIu2Etgj1zkoymeHi

Techone

Just watch your video. Thank you for showing the situation.

Let see what you got.  A DIY board under the Arduino board, a shield on top of the Ardiuno and the Arduino board. I can see also a battery connected to the DIY board, and I am assuming it power the servo. 

No 1, that is a lot of juices being use. What type of 9 V battery you are using and are you putting into the DC barrel ?  You need at least 300 ma to 500 mA into that Arduino setup. If it is not enought current being provided, the 7805 inside the Arduino will shutdown and place the Arduino chip into reset or the 7805 will be unstable. Here the thing... when a device take a lot of currents, the voltage in is going down, that cause problems.   

Ashleysmith

its a duracell pluss 9v battery

ill do a video of the exact problem (probably easier to show)

Techone

Quote
its a duracell pluss 9v battery


A square 9 V battery ? Are you sure ?   :smiley-eek:

Man.. That is no good for your set-up.  Use a 9 V pack --> 6 X AA or 6 X C.  A 9 V square battery don't have enough juice in them.

To confirm what I am saying... measured the voltage at the battery when you are connected to your setup. The voltage will be lower than 9 V. If it is going below 6 V... well... your poor ardiuno will not have its breakfast.  ]:)

Ashleysmith

http://www.youtube.com/watch?v=0UCLCxwy2pA&feature=youtu.be

ah right... my friend is using a 9v square battery and its worked fine, all this set up has to power is the reciever at 3.3v and the board it self

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