DC power jack not working

I have bean powering my Arduino Uno using a 9Volt battery plugged in to the dc power jack. This has worked on simple bread board projects so I am pretty certain that the battery and connector are OK.

I have just tried to use the same power setup to control two motor controllers each taking a max of 50mA and a compass module taking 25mA , three RC channels (?? mA) and a couple of LEDs. All looked fine (LEDs shining etc until I tried to use it.

The setup stuttered and died, and now the jack seems to supply no power at all. I assume I have blown a fuse. Is it mendable?

The set up works fine powering it using a USB cable to my computer but as this is a robot that is supposed to wander my garden this is not a viable option.

Alan

I assume I have blown a fuse.

No there is no fuse to blow.

Those square 9V batteries are rubbish for powering most things. A motor especially.

o control two motor controllers each taking a max of 50mA

You sure of that 50mA is not very much for a motor especially on a robot.

Measure the voltage on the battery under load.

There are 2 motor controllers, not motors attached and I am sure of the quoted current draw. I am not at the moment able to measure the actual draw.

If there is no fuse what has gone wrong? It still works using the USB cable!

Alan

AlanTJohnstone: There are 2 motor controllers, not motors attached and I am sure of the quoted current draw. I am not at the moment able to measure the actual draw.

If there is no fuse what has gone wrong? It still works using the USB cable!

Alan

Well then take voltage measurement while the poor little 9 volt battery is plugged into the arduino board. Read the voltage at the center pin of the DC connector and at the Vin pin and at the 5V pin. Report your readings. Then find a proper DC voltage source.

Lefty

I am an Idiot! There is nothing wrong. I tried A new battery when the problem started but I must have replugged the old battery in rather than the new one and got nothing lighting up so I thought I had blown something. For the record on the pin attached to a new 9volt battery I get 9.3V, 7.98V at Vin and exactly 5V at the 5V pin.

The 9Volt battery was supposed to be a quick test before using a Pololu Step Up/Down Regulator attached to the same 12V battery that runs the motors. I wanted to test things without the possibility of ground loops getting into the works. It had happily run everything but only one motor controller at a time as I put things together and tested. A combination of 2 controllers and a low battery seem to have beaten it. The old battery still delivers 7.25Volts across its terminals but that is not with a load attached.

Thank you for your help. I should have gone away and had a cup of tea and then come back and tested the battery rather than making wrong assumptions.

Alan