Power problems stacked Arduino shields

Question

I have a weird problem. I am currently building a BB-8. Therefore, I am using an Arduino Uno. On top, I have stacked an Adafruit Motor Shield v2.3 and, again, on top of this, I have stacked the Sparkfun USB Host Shield. The Arduino is powered by a 9V-Block battery, the motors are powered separately by two 18650 Li-Ion batteries. To control the two Pololu motors, which have a stall current of 1.6 amps each, I use a Xbox 360 wireless controller, where the receiver is connected to the USB Host Shield.

Now to my problem. Every seems to work fine, until i cover everything with a styrofoam hemisphere. Yes, you've read right. If that happens, the controller signals is lost and does not connect again, unless I restart the Arduino. I have uploaded a small video on youtube, where you can see the problem.

I guess, this is a power problem, since this issue does not occur, when I connect the Xbox receiver to my Mac. Has anyone an idea, how to solve this problem?

I already tried another power source. And the USB host shield should give enough power, since the specs are saying, that 500 mA is no problem, and hit is exactly the USB 2.0 spec. The combination of the shield shouldn't be a problem, too. I carefully chose this shields, because the motor shield is just using the pins A4 and A5, the USB host shield is using some of the digital pins, so I think there is no interference.

Thank you for your help.

EDIT I have tested it a bit more now and i think i can reduce the probable reasons. First, i tried some other power supplies, from AA batteries on the VIN pin to external power adaptors. Next, i tried other xbox receivers and controllers. I also tried a playstation 3 controller with a Bluetooth dongle. Nothing solved the problem. I also covered the Arduino with other things than styrofoam, like a garbage can, cardboard and some metal box. This worked, so the problem was only with styrofoam. Now i haven't covered the Arduino, but i slowly got closer. About 20 cm from the Arduino, it stopped working. My clue: static electricity. Do you think this can be a problem? And if yes, how can i solve this?

Answer 1

Try use single battery + separate voltage regulators for every load. Otherwise if one of the batteries discharges while other are ok, it can take all power of the system, something like short-circuit. Also you can receive a trouble if do error in ground connections.

Select good battery, which can provide enough power. If cant find a battery which can supply enough current think about using low current batteries in series to achieve extra voltage. Then reduce voltage using dc-dc step down converter.

For example if you have a battery of 24V which provides 1A (power p1 = 24*1). It can provide 5A if reduce the voltage to 5V using dc-dc. (power p2 = 5*5). Because p1*h=p2, where [h=0.8 - efficiency].

Answer 2

So, I solved the problem. As is mentioned in my question, the problem was static electricity. I primed the styrofoam sphere with some special primer to make the styrofoam a little more stable and so on. That's it. Luckily I didn't touch the Arduino with the sphere. I think it would have damaged the Arduino.