Arduino drains AA battery fast!

Hi, This is my first topic :smiley:
My Project is a car controlled with phone via HC-05 Bluetooth module
my project works good when I power it from the usb cable I used 9v batery to power arduino
and the bluetooth module and rgb led, And I used 4x AA batteries to power the L293D and the 2 motors.
So, the problem is the motors rotate very good for about 30 mins then the AA batteries are dead.

Well that's not the Arduino draining the batteries: I'd say that's the motors draining the batteries.

manor_royal:
Well that's not the Arduino draining the batteries: I'd say that's the motors draining the batteries.

Ok, sorry for that..
Is there a way or trick to make the motors drain less power ? (iam noob at electronics and arduino)

Hardizzer:
Is there a way or trick to make the motors drain less power ?

Simple physics: you employ a motor to do work, which requires energy. The rate at which that work is done, or the energy is consumed, is power measured in Watts. Watts are volts x amps, so for a given voltage the motor will need to be provided with a certain number of amps. Batteries' capacity is measured in amp hours, or milliamp hours, so for a given amp draw, you have a fixed number of hours available.

Hardizzer:
Ok, sorry for that..
Is there a way or trick to make the motors drain less power ? (iam noob at electronics and arduino)

Don't use them? Sorry, motors will use the power they need (plus some more due to inefficiency)...
A high power application will need big battery pack.

Is your motor the most efficient? Are your mechanical linkages efficient? All you can do it
try to reduce inefficency somewhat (unless its already grossly inefficient). Certainly replacing L293D
by MOSFET H-bridge will give you a big benefit (darlington drivers used at 6V are grossly inefficient)

So, Will changing the motors solve the problem ?

Hardizzer:
So, Will changing the motors solve the problem ?

If you can find a more efficient motor, perhaps. But you need to consider why one has the motor there in the first place: presumably to do work, like lift something or whatever, and in your case move the car. That means you need to provide energy, which is what the battery does. The battery contains a given amount of energy, denoted by its mAh rating. If you do the work quickly, you'll use the energy quickly.

Yes the energy supplied is partly wasted overcoming the losses in the motor, but who's to say another motor will have less waste?

As MarkT said though, the L293 is an inefficient driver, and loses energy to heat. That heat is running your battery flat but not turning the motor.

Ok thanks guys, Will try to change the motors if it didnt work I will try to change my L293D :slight_smile:

I'd say change the L293D for a low-loss driver first, that's the low-hanging fruit I bet.