L293D current specs and batteries

[vraedac]

I want to make sure I properly understand the power requirements for my proposed setup before I start purchasing parts and batteries.

In the motor shield user manual (http://www.ladyada.net/make/mshield/use.html) it is stated that the driver chips are designed for 600ma per motor, which to me indicates that the motors are wired in parallel. So, if I wanted to power four 6v DC motors with free-running currents of 70mA, I would need enough battery capacity to account for the sum of these currents, right? That is, if all four motors run with little or no resistance then I will be drawing 280ma from the batteries. So using four 1.5v alkaline batteries, which are rated at 2400mAh, should give me a rough battery life of around 8.5 hours, or a little less because the motors will rarely run with no resistance. Is this correct, or am I missing something important in my understanding?

Also, how do I incorporate the stall currents of the motors... if the motors have stall currents of 700mA, how does this factor into determining the battery requirements?

Thanks in advance for any help!

[adafruit_support_bill]

AA's should supply plenty of current to drive those motors. The motors are not really wired in parallel. There are two full H-bridges per chip and each motor gets its own.

As far as stall current goes, you hope that you never see 700mA for very long, since the device is only rated for 600mA continuous.

If you do expect that you will be stalling these motors in normal operation, you might take the precaution of socketing the L293D's so that you can replace them easily. You can also piggy-back 2 of them for more current handling capacity. http://forums.adafruit.com/search.php?st=0&sk=t&sd=d&keywords=piggyback

[vraedac]

great, thanks for the help.

[sukiduino]

Hi,

I am new to arduino so I do not understand all concepts to solve the following problem:

I need to drive 4 stepper motors concurrently and have 4 photo resistors controlling them.

because there is only limited number of I/O pis, do I need to use 2 arduino boards each having its own steeper shield?

[adafruit_support_bill]

Please start a new thread for this topic. You are more likely to get helpful repsonses if you start a new thread with an appropriate title.