Hello! I've been working on a school project and so far it's been run off my laptop. Unfortunately, there's no way to measure how much power it's drawing (it must be near 5V though, right?). The maximum is 14.4V, and I noticed that the motors aren't quite turning with the torque they should be getting. I've decided that I will get a 14.4V battery pack, but I need some help to not accidentally destroy my Arduino or motors. What I was thinking is some voltage regulator, based off the YouTube videos it seems pretty straight forward, however just in case I came here to ask.
Am I close to the right description of what I need? I also am not sure if the regulators can handle 14.4V, but some videos and documents suggest most can handle ~35V.
If you use a linear regulator, your limiting factor becomes heat. The higher the input voltage, the more power is wasted as heat. This is exacerbated by current draw. The more current you draw, the more heat at any given input voltage.
So, you'll almost never be able to run a linear regulator from a 35v supply without it getting WAY too hot to survive. At 14.4v, you're already pushing it. Look into switching regulators. There are snap-in modules that can work in place of a TO-220 linear regulator, as well as plenty of cheap options on eBay.
You seem to be confused about voltage and power, and I suggest you read more about it.
The web site you linked to for that ridiculous motor seems confused and uninformative, it sure doesn't help.
When you say "the maximum is 14.4 V", what are you refering to ? The maximum of what ? The motor voltage ? It seems not.
It doesn't really matter what the motor voltage is, you will need some kind of motor controller somewhere, even if it was a one volt motor, the arduino would not be able to supply the current to drive the motor directly.
The web site says that the stall current for this motor is 2.6 amperes when powered by a 7.2 V source, so it would be 5.2 amperes from a 14.4 V source. Motors briefly draw the stall current when starting up, and that is many times the current that a laptop can supply.
As mentioned, to use this motor you need both a separate motor power supply and a motor driver board. Be sure to connect the grounds together.
michinyon:
You seem to be confused about voltage and power, and I suggest you read more about it.
The web site you linked to for that ridiculous motor seems confused and uninformative, it sure doesn't help.
When you say "the maximum is 14.4 V", what are you refering to ? The maximum of what ? The motor voltage ? It seems not.
It doesn't really matter what the motor voltage is, you will need some kind of motor controller somewhere, even if it was a one volt motor, the arduino would not be able to supply the current to drive the motor directly.
Hello! I'm sorry I didn't clarify, here's what I meant by maximum:
This is a school project that I have completed. The only problem is that we're unsure if I'm allowed to have my laptop powering the robot, so we want to switch to a battery pack at the limit they allow, which is 14.4V.
The motor takes a maximum of 7.2V, but right now seems to be running fine at around 5V. What I was thinking was to get something to make sure that the power does not exceed what the Arduino and motors are rated for. A few searches told me I needed to get a voltage regulator, but I'm simply unsure of what exactly is necessary.
Edit: Also, I'm not quite sure what is wrong with the sites motor. They have some documentation available in the specification section if that helps. The parts for the project are supplied by this company for my school, I do not have much control over this. They have their own controllers and such, but we've decided to make this project through Arduino using their chassis, their motor, their wheels.
You really shouldn't be powering the motor from your laptop at all - that risks
damaging your laptop. The motor shouldn't be sharing its power with the Arduino at
all, a separate supply should be used.
There are several reasons:
Inductive spikes from the motor can't damage digital circuitry.
High current draw won't reset or interfere with Arduino or laptop
Motor voltage can be chosen to match the application.
MarkT:
You really shouldn't be powering the motor from your laptop at all - that risks
damaging your laptop. The motor shouldn't be sharing its power with the Arduino at
all, a separate supply should be used.
There are several reasons:
Inductive spikes from the motor can't damage digital circuitry.
High current draw won't reset or interfere with Arduino or laptop
Motor voltage can be chosen to match the application.
Thanks for telling me this, I didn't know. You saved my laptop! I think I will switch to battery pack anyways then. Could you read above? I've clarified saying how I plan to switch, and need some help finding a part that will make sure that my Arduino doesn't burn up and my motors are getting the current they should be. Also, by sharing power do you mean it's a problem to power the motors from the Arduino 5V pin or do you really mean connecting it to the same battery powering the Arduino, because I'm going to wind up having to connect the motors to the same battery running the Arduino.
nj_scioly:
I've clarified saying how I plan to switch, and need some help finding a part that will make sure that my Arduino doesn't burn up and my motors are getting the current they should be.
That would be the motor controller. The one linked on the site you listed uses a PWM signal (which you can generate from your Arduino) to drive the motor correctly. You need the motor + controller together. If you don't use the same company's controller, you need to build/buy an H-bridge controller of your own.
nj_scioly:
do you mean it's a problem to power the motors from the Arduino 5V pin
Oh gosh yes. That's a huge problem. That pin is derived from either the USB port (if you're powering the Arduino from USB), which is limited to 500mA MAX in most cases; or it's derived from the Arduino's built-in 5v regulator (if you're powering from the DC barrel jack), which will not live to see the weekend if you power it with 14.4v in, and try to pull up to 3A out.
That battery voltage is inappropriate for both the Arduino and your motor. You should really use a 7.2v battery like the motor's vendor suggests. That would also be about the right voltage for the input to the 5v regulator on the Arduino board.
nj_scioly:
I've clarified saying how I plan to switch, and need some help finding a part that will make sure that my Arduino doesn't burn up and my motors are getting the current they should be.
That would be the motor controller. The one linked on the site you listed uses a PWM signal (which you can generate from your Arduino) to drive the motor correctly. You need the motor + controller together. If you don't use the same company's controller, you need to build/buy an H-bridge controller of your own.
nj_scioly:
do you mean it's a problem to power the motors from the Arduino 5V pin
Oh gosh yes. That's a huge problem. That pin is derived from either the USB port (if you're powering the Arduino from USB), which is limited to 500mA MAX in most cases; or it's derived from the Arduino's built-in 5v regulator (if you're powering from the DC barrel jack), which will not live to see the weekend if you power it with 14.4v in, and try to pull up to 3A out.
That battery voltage is inappropriate for both the Arduino and your motor. You should really use a 7.2v battery like the motor's vendor suggests. That would also be about the right voltage for the input to the 5v regulator on the Arduino board.
Hello, thanks to everyone who has replied here. As you suggested, I have decided to use 2 7.2V batteries. 1 to power my arduino and another for the motors. There is a clear improvement to the performance of the motors when using the batteries they suggested, any problems with moving slowly or struggling with power are over. Once again, thank you all!
