Powering multiple servos for wearable robotics

Hi, I am working on a project to create wearable robotics and wanted to check if I have the right spec for the servo motors and power supply for my project. Any help would be really appreciated


This is the servo I am thinking of ordering for the project (Torque (6V/7.4V): 50/60 oz-in, 3.6/4.3 kg-cm): HS-5087MH HV Digital Micro Servo - RobotShop


With a 7.2V lipo battery pack: https://www.amazon.ca/RoaringTop-5200mAh-Battery-Connector-Truggy/dp/B08G1H8HMB/ref=mp_s_a_1_7?crid=1MEDN0VBDVGR0&keywords=74v+lipo+battery&qid=1640632719&sprefix=7.4v+lip%2Caps%2C177&sr=8-7

Project description/requirements:

  • Project will use between 8-12 servo motors to move lightweight fabric for a wearable garment

  • Ideally should be powered from one power supply - needs to be a battery so the wearer can move around outdoors, battery should last at least 15 minutes and be relatively small and compact so it can be hidden in the lining of the garment

  • Controlled using arduino nano

  • Will be worn outdoors in temperatures between -10°C to 5°C

My question is whether the 7.4V lipo battery pack will be enough to power 8-12 servos, or if there are any major issues I might run into with this set up that I’ll need to solve. If I need to split it into 2 separate circuits with two power supplies (4-6 servos for each power supply) I should still be able to fit that into the lining of the garment.

Thank you!

Hello @laserj and welcome to the RobotShop forum,

My question is whether the 7.4V lipo battery pack will be enough to power 8-12 servos.

Yes, it can power it but the question should be, for how long? And that depends on the capacity. A battery’s capacity determines roughly how long a battery will last at a specific voltage given a specific discharge rate. For example, if you choose a 7.4V, 2Ah (5200mAh) battery pack, the battery should be able to run a 7.4V motor consuming 5200mA continuously for 1 hour.
You can find more information about this here:

For the HS-5087MH you have:

  • Current Draw Idle: 3mA
  • Current Draw Stall: 1,750mA

So let’s approximate it 450mA continuous. If you use 8 servos you will have 3600mA, if you use 12 then it would be around 5400mA.

So with your 7.4V 5200mAh you should be able to power 12 7.4V servos for a little less than an hour. But keep in mind that if the motors stall they will draw much more current.

However, keep in mind that that you also need to power the Arduino, although won’t consume that much current.

The problem is that the Arduino nano only has 6 PWM pins, so you can only control 6 servos independently. If you don’t need to control them independently then it shouldn’t be a problem, but if you do you’ll need a servo driver, for example, a PCA9685.

Also, since you mentioned this is a wearable project I thought I should point you to the the DIY Wearables section of the store.

I hope that helps!

Hi, thank you so much for your advice, that’s so helpful! I ordered some of the parts to make a test and will see how it goes, thanks so much again I really appreciate your help