Hello everyone,
I am currently working on a 12 servo robot project and decided to use the 12-channel Mini Maestro.
The Servos (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16269) are powered by a 4xAA battery pack.
The controller is working fine with 8 to 10 servos connected. Connecting all of them causes the status lights to go off and the servos to run fullspeed aimlessly.
After looking through the forum I found out that there are some other people who had the same problem.
I am aware that the 4.8V pack is not really enough for 12 Servos, but using a 6V supply or even 2 4xAA battery packs lead to the same problem.
So i would really like to know:
Why are the servos not just shaking but moving with full force if they are allegedly underpowered?
What other battery do you suggest?
A Lipo with a ubec would be another option but I am not so very comfortable with a bomb walking through my house 
Thanks in advance!
It is amazing how often this question comes up, but the problem is always the same and the answer has been posted many times: your power supply is simply incapable of supplying the current your project requires.
In addition to servo misbehavior, the controller may be behaving erratically because of voltage drops. You need a battery or power supply capable of supplying several amperes of current. Just how much current depends on the mechanical load but as a guess, budget 1 ampere per straining servo. You could try this battery pack, but it may be too small: all-battery.com/6v3800mahnim … ector.aspx
Thanks for the answer!
I will try it with the battery you recommended.
My rule-of-thumb is 1A for a 9g servo. Scale that up a factor of four for your 38g servo and you have a massive power requirement.
My estimate may be very conservative. So you might get by with a lot less.
The servos’ current use goes up a lot if they are moving or if they have to “push actively”. So if you could restrict all your servos from moving all at once, you’ll be a lot better off. From what I understand, your servos go bonkers immediately at powerup, and don’t start to behave after a while. What I’m thinking is that your servo controller is getting too little power and resetting. This causes the servos to start moving to a different position, so the cylce repeats.
What would help reduce the large current-requirement is if you would separate the powersupply of the servos with that of the electronics. Now if all your servos start moving all at once, your “servo” powersupply will sag a bit, but the electronics will keep on sending hte proper signals. The result will be that when you start, the servos will be a bit slower in reaching the desired position, but things will settle down within a second.
This is more likely to work with “cheaper” analog servos than with the digital ones. For the digital ones, the digital circuitery in the servo might crash and do unexpected things when the powersupply sags. But the analog ones will simply move a bit slower.
I am using this battery now:
http://www.conrad.de/ce/de/product/206976/Conrad-energy-NiMH-Sub-C-Empfaenger-Akkupack-6-V-3300-mAh-Bauform-Hump-Stecksystem-BEC-Buchse
Everything working fine.