problem powering arduino RBBB from batteries

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nmakro
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Joined: Tue Apr 09, 2013 10:01 pm

problem powering arduino RBBB from batteries

Post by nmakro » Tue Apr 09, 2013 10:03 pm

Hi, i am trying to power my RBBB (atmega 328 pu, duemilanove, 5V) with 4 AAA batteries (4,8V 4000mAH). but when i connect the cables from my battery pack to any of the 5V pins and ground my board does not seem to work. If i power it through the FTDI cable everything works fine..

Is there a chance the 4,8 V are not enough and the board only works from 5V and above? i thought that these boards work even with 2,2 voltage supply.

Thank you for any suggestions..

paul
Site Admin
Posts: 735
Joined: Mon May 12, 2008 4:19 pm

Re: problem powering arduino RBBB from batteries

Post by paul » Wed Apr 10, 2013 8:43 am

nmakro,

I'm puzzled. You are measuring 4.8 volts at power pins from ground?

One word of warning on those batteries - those are rather large batteries and they really should have a fuse or PTC or something in the circuit - if you hook them up backwards at the RBBB you are going to vaporize the backwards diode and perhaps several pcb tracks on the board.

Another word of warning - you don't ever want to power from batteries and the FTDI at the same time because the voltages are going to conflict.

Try just blinking an LED, then disconnecting the ftdi cable and hooking up batteries to see if that works. Let me know if that works.

Paul

nmakro
Posts: 2
Joined: Tue Apr 09, 2013 10:01 pm

Re: problem powering arduino RBBB from batteries

Post by nmakro » Wed Apr 10, 2013 2:56 pm

paul thank you for your answer but i figured it out.. the problem was that i had my batteries connected to the motors for many hours without doing nothing and somehow my batteries have drained out because i suppose the motors draw current even if they are not working.. Plus that i thought that the ftdi cable i had for my RBBB only powered the arduino but apparently it was powering the motors too.. so i thought that somehow the batteries worked for the motors only if i had the cable for the arduino plugged in.. :p

paul
Site Admin
Posts: 735
Joined: Mon May 12, 2008 4:19 pm

Re: problem powering arduino RBBB from batteries

Post by paul » Wed Apr 10, 2013 4:15 pm

nmakro,

The power system of the RBBB is really simple so everything is connected together. You should be very careful though with those batteries. If you hook them up in reversed polarity to the RBBB very bad things are going to happen. Also you definitely don't want them connected at the same time as the cable.

Paul

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