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arduino, servo + external power: ground to arduino, double power's runtime? Answered

hope you may have a spare second to send an input
looking forward to your reply!

arduino, servo + external power, potentiometer, switches
ground to arduino

once i connect the servos' 6V power ground
to arduino's "gnd" pin i get uncontrollable results
with my potentiometer & switch;

if i disconnect the servo's 6V power ground
from arduino "gnd" pin
the potentiometers & switches work as required ...

can i simply NOT connect the servo's battery "Ground" wire
to the arduino ground pin?

better power supply

a 9v battery won't last you very long with servos ...

i've heard that one should wire 2 in Parallel
to double the power's runtime …
do i need any additional components for this?

how else may i enhance the battery's (motor's) runtime?



Best Answer 5 years ago

To help battery life there's really only three options, A: Bigger battery B: smaller servos C: limit how often you need to move/energise them.

And YES they should be wired in parallel like you said. FYI your schematic is missing the jumper between the 7805 and the rest of your system on the right half. hate it when that happens eh?

Hey guys, Isn't this basically a ground loop?

I see you have the USB supplying power, Try attaching you battery directly to the Uno's Vin pin (not the 5v pin!!). It will bypass the USB power in favor of the battery. It's worked for me a few times. Then add the ground back

Odd though, usually it's Adding a ground that fixes a prob like this. Good Luck !


Answer 5 years ago

Thanks for your reply & hints, wired_!

As for the battery:

i am try all the options (smaller servos, big battery,

less movement* coding) right now (but already

see the benefits)

connecting the battery to the Vin pin worked!

i scripted a lot of movements* so it drained

my battery faster than using 2 sources

(power via usb & additional battery) solution


*since i did not post my code:

whilst reducing the movement i found an error

which most likely caused my problem (wrong addressing

& calling of pins … too much interfering movement)


i corrected the voltage part within my sketch

(pls. see image attached below ... yep - hate it when it happens :) …)


Answer 5 years ago

Right on ! glad it helped :)

Just a thought for the battery though, Rather then using a 9v that has something like 900mah Try looking at rechargeable AA's. Most major brands will have a 2.5aH rating. Granted you will need 6 of them, wired in series, to overcome the 1.2v drop through the regulator. Would still keep it portable with a bit over twice the capacity.


4 years ago

7806 can power 5 servo's from Mg995 ,

I will give 7th power from battery 7 volt , 4 ampere