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### Topic: Powering 23 servos? (Read 1 time)previous topic - next topic

#### Geeko

##### Mar 19, 2011, 10:37 pm
What are my stationary options here? What is my mobile options?

I am powering 23 hitec servos, for now I just need something for a demo. Later on I need some kind of battery powered option.

#### Grumpy_Mike

#1
##### Mar 21, 2011, 12:50 am
Before any answers can be given you need to know (and tell us) the voltage and current these servos require.

#### Geeko

#2
##### Mar 21, 2011, 01:58 am
Eh, stupid mistake. 4.8-6V, and I am unable to find current information. :/
Torque (Kg-cm/Oz-in @6V): 72/89 -- digital servo.

#### vinceherman

#3
##### Mar 21, 2011, 03:55 am
Do you have the model number from the servos?

#### Grumpy_Mike

#4
##### Mar 21, 2011, 05:11 pm
Quote
I am unable to find current information.

Well you will need to know that, if not from the data sheet then from measuring it. It is also best to measure it under full load. Then multiply up by 23 to get the total load.

At a conservative guess of 200mA per servo then you have a total current of 4.6A which is quite a lot. For 5V this is 23 Watts.

So for mobile then a lead acid battery might be good, you could get the 6v motorcycle ones.

For fixed then you are looking to convert / use a PC's PSU.

#### Geeko

#5
##### Mar 21, 2011, 09:53 pm
Current Drain (6.0V): 9.1mA/idle and 500mA no load operating

This is all I could find. All I need is 30 minutes of operating time.

#### Grumpy_Mike

#6
##### Mar 21, 2011, 10:00 pm
Quote

Wow any idea of the current on load?

That puts the current at 11.5 Amps and for 30 mins will require a 6000mA Hour battery minimum. Probably a lot more given that they are going to be on load.

You are then into the calculation of duty cycles, that is, are all the motors on all the time. This will reduce your battery requirements or extend your time. But I am sure you can do the maths as well as me.

#### Geeko

#7
##### Mar 21, 2011, 10:18 pm
Unfortunately this is a humanoid robot, none will be at full load but most of them will probably have 1/10 - 1/2 load constantly. I don't have anything at home to measure current. I'll have to purchase something some time.

#### Grumpy_Mike

#8
##### Mar 22, 2011, 12:41 am
You can get a cheap multi meter from a thrift shop for \$5 so there is nothing to stop you.

#### Geeko

#9
##### Mar 22, 2011, 01:23 am
Yea, I got one but its strict voltage. -_- Junk. I hate it.

#### zoomkat

#10
##### Mar 22, 2011, 07:04 am
Quote
Yea, I got one but its strict voltage. -_- Junk. I hate it.

If you live in the US you can get reasonably decent multimeters for \$5-\$25. So if you are serious about building a humanoid bot, you need to get the required tools.
Why I like my 2005 Rio Yellow Honda S2000  https://www.youtube.com/watch?v=pWjMvrkUqX0

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