I am building a robotic arm with five SG90 9g micro servos to flex each finger and one MG996R servo as an elbow joint.

The servos were working inconsistently, with not enough torque and jittering a lot. After doing some research I soon realised that using the 5 V supply form the Raspberry Pi was a terrible idea.

I've tried looking for ways to externally power the servos, but I've just ended up more confused than I was before.

I like the idea of using AA battery packs rather than an external wall adapter.

The question is: How many batteries would I need to power all servos (possibly simultaneously)? Maybe a few 4×AA packs in parallel?

SG90 9g micro servo: Operating voltage = 4.8 V

MG996R servo: Operating voltage = 4.8 - 7.2 V

Any help is appreciated.

  • \$\begingroup\$ Try connecting them to the same power source as the raspberry pi, instead of through the raspberry pi? \$\endgroup\$ Commented Jun 18, 2020 at 13:21
  • \$\begingroup\$ I can't really do that because the way i power my raspberry pi at the moment is through a micro usb to my laptop. Maybe the batteries solution could also power the raspberry pi? That way i wouldn't need the micro usb cable. \$\endgroup\$
    – user255652
    Commented Jun 18, 2020 at 18:32

1 Answer 1


The MG996R draws 2.5 A at 6 V. SG90's draw about 0.75 A peak each, for a total of up to 3.75 A peak for 5 servos. Therefore you need a battery that can deliver ~6 A.

A 4 cell (4.8 V) AA Eneloop pack would probably do it, but 2 packs in parallel would be better. If you use individual cells in battery holders the springs will drop more voltage than the welded joints in an R/C receiver pack, and then you will definitely need two 'packs'. Another option might be one 4.8 V pack for the SG90's, and another 6 V pack for the MG996R.


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