powering up Arduino board + 2 shields

Hi everyone,

I've a little project with Arduino UNO, Ardumoto shield and a LCD shield, but I'm having some trouble to power up everything. Without any motor connected to Ardumoto I can run my program and get appropiate feedback from the LCD when using the power from the USB output. However, once I switch to a 9V supercell battery the LCD doesn't respond as programmed, showing some strange characters.

I'm still not dealing with the issues that can arise when connected an indepenent power supply to drive the motor, but it seems to me that the 9V supercell battery can't power up the Arduino board plus 2 shields. Is that right? Should I use a different battery?

Thanks in advance

I am not sure what a

9V supercell battery

is. Do you have a URL to the specs.? Check the Vin with a volt meter when you power up. If it stays above 7 volts, the battery is not causing the problem. Does it stay above 7 volts?

9V supercell http://dx.com/es/p/gp-supercell-9v-aka-1604s-6f22-769 (I guess it's very low quality but I needed something to try it out)

Board was working fine during today's test, LCD showing correct values and all. However, I started meassuring voltages and it seemed strange the battery was being depleted very fast (real time fast), and I started to get values below 7V. Could that be normal?

Looks like an alkaline PP3 - no good at all for powering a motor shield (and will struggle with other shields probably). 6 AA rechargables would fare much better. But which motor? How much peak current can it draw?

PP3 9V rechargable battery might fare a little better, but in general these batteries are not rated for high current (100mA is pushing it), they are designed for powering transistor radios only.

Thanks for all your responses.

Anyway, I was talking about the battery powering up the shields logic, without any motor connected. The Ardumoto shield has the capacity of using an external power source to drive the motor, I think in that case I've to disconnect it from the Vin pin in the Arduino board, but keep the 5V pin. Correct me if I'm wrong.

I plan to use 6 x regular 1,5V rechargable batteries as an external power source for the motor, I'm not sure if it's a good choice. It's going to drive a stepper motor such as this one: http://www.abra-electronics.com/products/42BYGHM809-Stepper-Motor-%252d-68-oz.in-(400-steps%7B47%7Drev).html

What is the stepping motor voltage ? What is its current (amps) ?

sorry, I thought the link was enough: Stepper motor is 2 phases, 3V, 3.4A Battery set is 6 x AA 1,5V

Stepper motor is 2 phases, 3V, 3.4A Battery set is 6 x AA 1,5V

If you need 3V then why use 6 AA 1.5 batteries That would be 9 Volts. (3 times your needed volts). 3.4 amps is a lot of amps for the AA batteries I think. You need a bigger power supply for the motor!

Well, my plan was to use some spare parts I've, hence the AA batteries. Since I knew I would probably push the battery max current to its limit I thought of using multiple of them so they wouldn't be depleted so fast (also, because I have a 6 battery holder). I was thinking on using power resistors to met the 3V the motor requires. I don't believe overheat could be a problem since my application only requires a dicontinuous slow motion. Anyway, you're probably right about the batteries still not being able to deliver the necessary current.

One last question: according to motor specs its current is 1.7 Amperes per phase, I said it requires 3.4 A because it's a 2 phase stepper motor. I think my maths are correct since at some moments both coils of the stepper demand the 1.7 A, right?