Arduino L293D motor driver overloaded

Projects General Guidance
1

Hello
We have had an assignment in class to build a car that uses 4 DC motors, powered with Ardunio Mega + Uno + L293D motor shield

We have been using it for a while with a 12V 2.0Ah battery and it was all good
Today, for some reason, the shield started to put out smoke (shortage we assumed)

We weren't able to find any place of shortage or something like that and we've been wondering if it is possible that L293 doesn't work well with said battery? and maybe it was getting defected over time?

I am asking because I did read it fits A 4.5-24V battery but sometimes the capacitors they use don't quite fit..

picture added below, we're still trying to find a physical shortage - ty in advance

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2

What is the voltage rating on the electrolytic caps on the board?

What is the stall current of the motor(s)? The ancient and inefficient L293 is only good for 600mA continuous and 1.2A peak (for a very short time).
If the motors draw more than that you are stressing that crappy motor driver.

3

Please post a link to their datasheet....

4

Best to recycle the L293 shield and buy a modern, efficient brushed DC motor driver that can easily handle the motor stall current (look it up).

Pololu has the best selection: Pololu - Brushed DC Motor Drivers

5

Sadly I couldn't find any, but its those common yellow DC motors - 600mA each i believe (3-6V)

6

We would love to, those products were given to us by our college to be honest

7

Sadly I do not have the board as of now. the motors are indeed those common yellow 600mA 3/6V motors

How would you recommend we measure each drawn motor current?
(we did measure the voltage and it was between 3-6v )

8

In the absence of a data sheet, the stall current can be estimated. To estimate the stall current, measure the motor winding resistance. Zero your meter lead resistance before measuring the motor coil resistance. Take several measurements rotating the motor a bit between readings. Use the lowest reading in the calculation. The estimated stall current is the motor supply voltage divided by the measured resistance.

If your teacher still insists that you use that ancient and inefficient driver, you may point out that using the most modern and efficient components is good engineering practice.

9

Remarkably poor educational value, and completely wasted if they burn up on first use. Unless that was the real lesson!

Skip your next cup of cappuccino, treat yourself to this driver and proudly demonstrate the smoothly functioning result of your initiative to the instructor.

10

6V motor and 12V power supply? Hmmm.

11

Probably a good thing that the L293 sucks up 2V to over 4V in its output drivers and wastes that power as heat.*

*sarcasm

12

Well - if each motor takes 0.6A we need to provide it 2.4A - can it be done with a lower voltage battery?
We tried those square 9V but the motors moved so slowly

13

Tbh we were using it for a while and suddenly that happened
i wondered if there is en external current shortage or they product (shield) got defected over-time

14

That exact chip is used on the current Adafruit v2 motor shield.
The old/outdated v1 version with the L293D chips should have long disappeared from shops.
Leo..

15

I heartily agree, but this thread is about the L293D, on a different "shield".

16

Is it?
Leo..

17

See post #1. You are the only one to mention Adafruit.

18

I assume Adafruit designed, and discontinued, that v1 motor shield,
and DK Electronics (and many others) are still selling the exact clone of it.
Leo..

19

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