correct way to connect high-torque servo to power


I am new to Arduino, and I have some noob questions :slight_smile:

I prototyped my first project using the starter kit, but now I want to make it real and I am facing the following problem, for which I'd need some guidance/advice.

I bought an LD-3015MG high-torque servo and of course it doesn't work if I simply plug it where the starter kit servo was plugged.

Reading through the specs I see that it needs a voltage between 6 and 7.4V and a current of at least 1A (if I understand correctly what "min working current" means).

Because of this I was thinking about using an external power supply (like this one) just for the servo, while keeping the board powered with the USB cable (or anyway something more standard for it.

Also, I was thinking to connect the servo to the power supply using one half of the breadboard via this connector, while using the other half for the rest of the circuit connected to the board and to the 5V power, also connecting the grounds of the two halves together as shown in this very useful post.

Does the above make sense? Can the breadboard deal with 1-2A?

Thanks a lot for any help and/or advice!

No, a breadboard cannot handle those currents, they are designed for logic level voltages and currents.

These 5.5mm connectors are more suited to the higher currents required. You need to break the servo signal and ground out with light gauge wires on the servo to make things work.

Just a comment in general is that you’ll find the Chinese no name power supplies to be woefully underrated, you’re typically lucky to get 50% of the rated amperage and even that will not be on a continuous basis. You’ll also find they are questionable when it comes to safety, the isolation techniques most times are marginal and if they have any testing lab marks, they’re usually fraudulent. So, be careful with what you choose, I stick with name brand supplies from a reputable distributor like DigiKey or Mouser. IMO it’s not worth the $5-$10 you’ll save with unknown Chinesium supplies.

PS: karma added for proper links on your first post.

Thanks a lot for the reply and the useful suggestions :slight_smile: !

You need to break the servo signal and ground out with light gauge wires on the servo to make things work.

Could you suggest some reliable light gauge wires? Would something like this be ok?

Also, I need to connect the 2 grounds (servo and board) together. Is it ok if I plug the two power supplies to the same socket?

And you'll want a lot more than a 2A power supply to be safe. When a servo just starts up or is stalled it draws a lot more than the minimum running current. Often 5 times as much. I would choose at least a 5A power supply, maybe more. And unless you really need the absolute maximum power and don't care how long it will last I'd probably stick to 6V.


The thing is high torque, 1.5Nm, so it will need much more power than 1A. 2.5A is my estimate based on the torque, speed and normal gearing losses.
Manufacturer datasheets for most hobby servos are pretty rubbish alas. The assumption is its in a standard RC configuration powered from a receiver battery pack (many amps available). Receiver packs used to be NiCd, then NiMH, and now LiFePO4. All high-current capable.