12V Battery


I would like to connect my 4 motors through motor driver,arduino and servos. Each motor have 2A peak current, the servo has 7.5V peak voltage.

  1. Can I make 8 AA batteries so that become 12V then connect it to all of the above(4 motors with motor driver, arduino and servo through buck converter)

  2. Can i just connect the batteries together using normal wire and solder it to the batteries?

Why make a pack of 8xAA to give 12V when you say you need 7.5V?

Don't solder to the batteries: I tried that as a kid years ago and when I tried to solder a wire to the +ve "pip" I actually made the battery lose its connection inside the case.

8 AA batteries are not going to have enough capacity to run your motors etc. (maybe briefly depending on the battery type, but not for any period of time). A 12v battery (assuming you are talking about a car battery etc.) has lots of capacity but you need to be careful and fuse your supply lines - a car battery has enough current to melt wires, start fires, burn the end off wrenches etc. if you are not careful and get across the posts. It is not clear why you are creating 12 volts when you say you need 7.5 or are the motors rated for 12 volts while the servo is rated for 7.5 ?

sorry, i forgot to mention that my motors has 12 rated voltage and my servo has 7.5V.

So how am I going to power up my system using AA batteries? Any suggestion?Thanks ^^

12V DC motors will work on lower voltages -- they will turn more slowly and have less torque.

If you need the speed, an option is to run the entire system on low voltage and use a DC boost converter to increase the drive motor voltage, as done on Pololu's 3Pi. Pololu 3pi Robot

I don't beleive your servos operating voltage is 7.5 V. I think it is 5 V . Post a link for your servos or provide some proof that the servos recommended operating voltage is 7.5 V.

Here is my servo link

Btw I need the motor's torque and that's why I need 12V to power it. I bought a rechargeable 12V charger but i hasnt arrive yet. So the only solution I have for now is by using 8 AA batteries, but I want to ensure that it is safe and can power up the whole system

Just as I thought.

Operating voltage 4.8-7.2V

This is the servo maximum operating voltage range. Note it does NOT say 7.5 V !


This is telling you that if you do not want to burn out your servo , to pick a voltage just above the low end and NOT near the high end, ergo 5V (or up to 6V but not higher).

Use 5V.
Almost ALL RC servos are designed for about 6V but work fine at 5V
MOST BECs both built in (to ESCs) or STANDALONE are 5V but some are switchable with one of multiple possible output voltages .

A BEC is a circuit that provides servo power to flight control servos when the MOTOR ESC burns out (because you are flying too fast and overheat the motor or your prop is too big). This allows servo control to make an emergency landing . Hobbyking is out of stock of all their BECs right now but there are thousands of other suppliers.

This is why no experienced model aircraft pilots NEVER use the built in BEC that comes with the ESC to power their servos. They always use a standalone BEC (Battery Eliminator Circuit, so called because early model aircraft had separate 6V batteries for the servos. Modern model aircraft have a BEC running off the main flight battery. Even if the battery runs down enough to stop powering the motor, it will still power servos because the difference in current draw between the motor and servos is so large.

Bottom line. Run you servos on NOT MORE THAN 6V !

Better yet, buy a 3A standalone BEC from Hobbyking. (12v input from battery, 5V output to servos.DONE)

I would like to connect my 4 motors through motor driver,arduino and servos. Each motor have 2A peak current, the servo has 7.5V peak voltage.

I would like to connect my 4 motors through motor driver,arduino and servos.

It might help to know HOW MANY servos ?

It might help if you posted a link for your motors (we don't have a crystal ball . The word "motors" tells us absolutely nothing we need to know besides the fact that you could PWM them and that you will need something to drive them, which we couldn't possibly tell you without more information about them.)

FYI, Helen (with 15 posts, 0 karma), you are obviously new here. the way it is supposed to work is you START your post by telling us WHAT you are doing and WHY you are doing it. THEN (and only then) do you ask the technical questions. WHY ? Because the job you are asking us to do is (technically) called Application Engineering. The customer (usually a company wanting to use an IC made by LINEAR , asks Linear for advice on how to use their IC). Granted, this is on a much smaller scale here on the forum and there are times when it is nothing more than a simple question about a resistor , but the point is we need to know all the details about the application because there may be factors that YOU, the inexperienced user , think are irrelevant , which , in fact , change everything about the way the project is approached. If we know the "BIG PICTURE" we can give better advice. An example of a detail left out being critical and possibly having catastrophic results, is someone posting for help getting a LED strip to work (power supply , voltages etc) and neglecting to mention that they plan to install it in the ceiling of their room in their house. In case you are unaware, electronic circuits can catch fire if improperly designed or wired, and putting an electronic circuit in the ceiling of your room would definitely affect the responses to the post as to how to power and wire it.

So, what are you doing and why ?