Arduino and batteries

Hello.

I have a 9v battery adapter like this one:

http://playground.arduino.cc/Learning/9VBatteryAdapter

I noticed that all my projects (on Arduino Uno SMD) work fine when the Arduino is attached to the USB plug, but behave strangely (or don't work at all) when connected to the 9v battery.

What could be the reason of this?
Sorry, but I don't have a strong background in electronics.

Thanks

Have you got the polarity right? Have you build the adapter yourself? Is the battery maybe dead?

You might have soldered the wrong wire to each end if that is possible. It might be as simple as having a low battery. Try the battery first then try the soldering if and only if you are the one who soldered the pins in the first place. if not try sending it back.

Hope this helps,
~aaaelite21

Simply a battery like that is not much use for powering an arduino for very long.

friol:
Hello.

I have a 9v battery adapter like this one:

Arduino Playground - 9VBatteryAdapter

I noticed that all my projects (on Arduino Uno SMD) work fine when the Arduino is attached to the USB plug, but behave strangely (or don't work at all) when connected to the 9v battery.

What could be the reason of this?
Sorry, but I don't have a strong background in electronics.

Thanks

What projects? What does "behave strangely" mean?

4 Alkaline AA-cells or 6 NiMH AA-cells in series will power the Arduino for a long time.
They have 2000-2500 mA-hr of energy. The 9V batteries have only on the order of
350 mA-hr or so, and cannot provide as much current as the AA-cells.

Sorry for being unclear on this: I didn't build the battery plug, I've just bought it (so I think it should be wired correctly).

So, maybe the battery is not powerful enough for Arduino? What should I use instead?

See reply #5, also see [picture is not for part on the page],

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2128083_-1

DuaneB's tutorial said the PP3 style battery was good for powering the Arduino itself but it's clear that the board mustn't be powering any plant which of course needs its own power. He mentions 10mA for the Arduino while controlling some servos, which have their own power; that's 35 hours for a 350mAh PP3.

oric_dan(333):
4 Alkaline AA-cells ... in series will power the Arduino for a long time.

But at a nominal 1.5v each that's nominally 6v, and this very site says (for Uno anyway) that 6v is minimal, >7v is suggested. When your 4xAAs go slightly flat, it'll be below the minimum never mind further below the recommended.

I look forward to comments here, because this whole battery thing is crucial to portability.....

Four NiCd or NiMH cells gives you around 5V which could power the Arduino 5V directly? Or two LiPo cells going via the regulator. (There is at least one Arduino clone with an integrated LiPo controller.)

PeterH:
Four NiCd or NiMH cells gives you around 5V which could power the Arduino 5V directly?

It says here that although the USB supplies 5v, if you power it through the jack or Vin you need 6v min, or >7v preferably.

JimboZA:
It says here that although the USB supplies 5v, if you power it through the jack or Vin you need 6v min, or >7v preferably.

Yes, but you always have the choice of providing your logic voltage directly to the 5V terminal, i.e. bypassing the onboard regulator, or going through the regulator. If you go through the regulator, then you need to provide a couple of volts extra to deal with the voltage drop within the regulator.

PeterH:

JimboZA:
It says here that although the USB supplies 5v, if you power it through the jack or Vin you need 6v min, or >7v preferably.

Yes, but you always have the choice of providing your logic voltage directly to the 5V terminal, i.e. bypassing the onboard regulator, or going through the regulator. If you go through the regulator, then you need to provide a couple of volts extra to deal with the voltage drop within the regulator.

Keep in mind that the Arduino folks don't recommend powering the board directly from the 5V pin and several people have suggested the latest Uno R3 uses a on board 5 voltage regulator that is 'sensitive' to that. The following is from the arduino product description for the current Uno:

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.

My recommendation if one wants to power their board from a regulated +5vdc voltage source is to use a spare USB cable and power the board via the USB connector on the board.