How to Power 8 DS3218 Servos?

Other Hardware Motors, Mechanics, Power and CNC
1

I'm currently working on a quadruped walking "robot" (honestly, i shudder to call this abomination a robot). I need to move 8 DS3218 servos simultaneously, and I was wondering what the best external power source for this would be. The servos are all connected in parallel.

So far, I've been connecting 3 9V batteries in parallel, which can only power 3 servos at most. My working theory for why that kinda works is that since voltage is equal in parallel circuits, the servos aren't getting fried, but I keep needing to add more batteries to allow every servo to get about 2 A of current (current is split among each parallel component). Obviously this isn't sustainable, so is there a single supply bank I could use to power all these servos at once? Replacing the servos with another type would destroy me (they were expensive!)

2

Sum up the need for stall current for each servo and get a power supply capable to deliver that current.

PP3, block batteries? Put those batteries in fire alarms, or TV remotes. They don't provide current enough.

From the datasheet: Stall Current: 1.8A/2A (6.0V/7.0V)
If all servos start at the same time You need a 16+ Amp power supply.

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3

Thanks for the advice! I'm having trouble finding a power supply that fits those specifications, do you have any recommendations?

4

How will the servos be running? Stall current is at the start but later the need for current is lower. Likely less then 20 Amp supply will work.

What suppliers have You tried?
I don't recommend Ebay but Banggood, Amazon usuallly delivers useful things.

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5

The servos will not be running for longer than a minute at most.

I've just tried searching up "6 amp 20 volt power supply", but nothing really fits that exact specification. I found this dc converter and figure that I can attach two of them in parallel to two of these. Would this blow up my house? I don't really want to mess around with wall sockets, but no portable power source fits what I need.

6

That is not the critical point. The start is critical, how many might startn during the same second. After that the running current is the parameter to manage.

You posted a link to cables.... DC converter.... You first need to sum up, estimate, the need for current. 10 Amp sounds like low.

7

Using 2 such supplies, supplying 4 servos each might be a solution.

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8

All of the servos will be running at the same time since I'm doing a 2-beat walk cycle. Like you suggested, using two of the 5 volt 10 amp DC converters I linked earlier as a power source should theoretically get each servo 5 volts and 2.5 amps, right?

Is this a sufficient solution, or is there a single portable power source that would work instead?

9

Yes, correct.

Portable? It's up to Your muscles. Joking! There are more powerful supplies, size like a 1 liter milk package. Just look around, search.
Just know that Chinese supplies either deliver the Amps, or the Volts but not always both at the same time.

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10

I like 18650 rechargeable batteries. Maybe a 2S1P or 2S2P pack of these batteries with a discharge current of at least 10 or 20 amps for cell.

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11

Thanks so much for all your help!!

12

I'll definitely look into it; thanks!

13

I am looking to do something similar with 5 servo and a stepper, 2 servo are DS3240 and the others are DS3230MG. I need 6.8V and about 10 Amps. Would this be possible with a single battery?

14

@pnolan525 - Refrain from hijacking topics. You have two topics with the same subject of servos:

  1. Programming robot arm to be controlled with N64 Controller
  2. Arduino Uno PWM causing bad twitch
15

I apologize, I waited 26 days researching with no reply then posted my issue, due to no response on this comment. Those are 2 separate topics in two separate categories. I will try and wait the 6 month until it closes next time.

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