HEY GUYS,
i have 2 dc motor connected to the l293d motor shield. the program is ok when i run it no error and the dc motor is running when i plug the arduino to the computer. the problem comes when i unplug it to the computer and just using 9v battery, it cant run the dc motor. the 9v is connected to the motor shield not in arduino. is it a battery issue or power shortage or what?
i hope you could help me.
Hi,
What are the specifications of your motors.
If you are using a smokedetector type 9V battery then that will be the problem.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png or pdf?
Tom.... 
this is the image of the connection. am i using a wrong type of battery or dc motor?
Those batteries aren't good for much current, and do not last long either - low capacity, just a few hundred mAH.
CrossRoads:
Those batteries aren't good for much current, and do not last long either - low capacity, just a few hundred mAH.
soo i have a power shortage thats why it cant run the dc motor?
Either a power shortage from battery, or you need to change jumpers or something on the board so power comes from the battery and not the USB connector.
CrossRoads:
Either a power shortage from battery, or you need to change jumpers or something on the board so power comes from the battery and not the USB connector.
any suggestion on what kind of battery i will use? nad about the jumper, what jumper?, the connection between the battery and motorshield?
HI,
If you are using a shield can you please post a copy of your sketch, using code tags?
They are made with the </> icon in the reply Menu.
See section 7 http://forum.arduino.cc/index.php/topic,148850.0.html
Tom.....
cejans:
any suggestion on what kind of battery I will use?
Paul__B:
Nothing smaller than a carrier of six "AA" batteries.
where should i connect this in the arduino or motor shield?
Post a link for your motor shield. Almost ALL L293 Motor shields have a jumper that selects 5V power source for the Motor Logic. (look at the L293 datasheet. You'll see the chip has one pin for motor power and a separate pin for 5V logic power. The shields have a jumper. If the jumper is present, the 5V logic is powered by arduino +5V. If jumper absent, a separate power source can be used. Read your manual.
FYI,
The 9V smoke alarm batteries are rated for about 250 - 300 mAh. Since your motors probably need AT LEAST 300 mA, each motor would get less than 150 mA with one battery, not to mention that it would probably on run one motor for less than an hour.l
raschemmel:
FYI,
The 9V smoke alarm batteries are rated for about 250 - 300 mAh. Since your motors probably need AT LEAST 300 mA, each motor would get less than 150 mA with one battery, not to mention that it would probably on run one motor for less than an hour.l
additional info of the problem, when i run motor using the 9v battery with 127 speed only one of the two dc motor run. but when i put 255 neither of the two will run. but if it is plug to the computer any speed will do run the two dc motor.
so if i use this, will it enough to run my two dc motor?
raschemmel:
FYI,
The 9V smoke alarm batteries are rated for about 250 - 300 mAh. Since your motors probably need AT LEAST 300 mA, each motor would get less than 150 mA with one battery, not to mention that it would probably on run one motor for less than an hour.l
this is incomplete at best and plain wrong at worst, i suspect incomplete.
a 300 mAh battery can put out more than 300 mAh and good 9v batteries can but not for very long at all. i agree the 9v is a bad just didnt want people to think a batterys mah rating is also its constant current rating.
For those interested google "battery C rating" mah/1000 * C rating = constant current capability.
@cbrunnem,
Really, who cares ? The point is that's the wrong battery to use.
Without nit picking, suffice it to say that you should never use a smoke alarm battery to drive motors, period. (there might be some micro motors that would constitute an exception but let's assume we are excluding those.
HEY GUYS, did you just answer my question about the battery?
if i use 6 or maybe 5 AA battery, with 1.5v, how much C rating or mAh will that be?
will it be enough to run?
tnx.
cbrunnem:
this is incomplete at best and plain wrong at worst, i suspect incomplete.a 300 mAh battery can put out more than 300 mAh and good 9v batteries can but not for very long at all. i agree the 9v is a bad just didnt want people to think a batterys mah rating is also its constant current rating.
For those interested google "battery C rating" mah/1000 * C rating = constant current capability.
if i use 5 or 6 AA battery will that be enough?
AA cells have ~ 2500mAH capacity. 4 or 5 or 6 in series have higher voltage, but same mAH capacity.
CrossRoads:
AA cells have ~ 2500mAH capacity. 4 or 5 or 6 in series have higher voltage, but same mAH capacity.
does it have more power than the 9v battery?
cejans:
does it have more power than the 9v battery?
Six AA cells in series gives ~9V and 2500mAh.