Author Topic: Connecting 6V Battery For Servos to Iteaduino  (Read 2725 times)

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Offline SUTO the GTopic starter

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Connecting 6V Battery For Servos to Iteaduino
« on: March 06, 2013, 08:34:26 AM »
Where to connect 6V Battery on Iteaduino Dev. Board? (I am guessing: to the +5V and GND pins but want to be sure!)
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Offline newInRobotics

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #1 on: March 06, 2013, 09:06:57 AM »
I guess not, because on the board it says +5V and battery is +6V. To power it You should use cylindrical connector at the corner of the board, from what I've seen it takes anything from +7V to +23V (don't take my word for it, check datasheet).
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Offline jwatte

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #2 on: March 06, 2013, 11:45:00 AM »
You connect the battery to the barrel connector, or to the "Vin" pin.

Unfortunately, a 6V battery is not going to work well, because the regulator on the Arduino boards has high drop-out (1.5V - 2.0V) so the minimum stable input voltage is 7V. Also, the battery voltage will drop with discharge.

Not all is lost! Get a 5V output step-up-down DC DC converter from Pololu, hook the battery to the input of that, and hook the output of that to the +5V connector, and you will be good to go. Additionally, this will let you use a variety of batteries, across their entire discharge cycle. (Don't over-discharge batteries if they are Lithium based, though; that destroys them)
The S7V7F5 can give you up to an amp of power, and is highly efficient, for $4.95: http://www.pololu.com/catalog/product/2119
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Offline SUTO the GTopic starter

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #3 on: March 06, 2013, 02:48:22 PM »
@newinrobotics So I only need one battery pack (7-23V)? I taught  I needed two! One for the Servos(4.8-6V) and one for the board (7-23V)! So I only need to power the board, lets say with a 9V battery and thats all? I can connect the servos to the VCC and they will get enough power?
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Offline newInRobotics

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #4 on: March 06, 2013, 03:45:10 PM »
Quote from: SUTO the G on March 06, 2013, 02:48:22 PM
@newinrobotics So I only need one battery pack (7-23V)? I taught  I needed two! One for the Servos(4.8-6V) and one for the board (7-23V)! So I only need to power the board, lets say with a 9V battery and thats all? I can connect the servos to the VCC and they will get enough power?
Right, You can use as many battery packs as You want, however, maintaining many packs is more difficult than maintaining one. Don't connect Your servos to Vcc, as I believe, that is for electronics only (low power bus) and will get fried at higher currents. In Your case You can use separate power supplies or use one power supply together with voltage regulator for servos (preferably switching voltage regulator, as non-switching one will waste a lot of power as heat).
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Offline SUTO the GTopic starter

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #5 on: March 06, 2013, 11:07:53 PM »
I can connect it this way? And 9V battery to the barrel Jack connector! And I am good to go?
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Offline newInRobotics

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #6 on: March 07, 2013, 01:43:14 AM »
Quote from: SUTO the G on March 06, 2013, 11:07:53 PM
I can connect it this way? And 9V battery to the barrel Jack connector! And I am good to go?
Just check the datasheet. From the picture one cannot possibly tell power rating of the bus. yes, 9V can go to barrel connector.
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Offline SUTO the GTopic starter

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #7 on: March 07, 2013, 04:27:02 AM »
From this datasheet how can I tell the power rating of the bus? (All I see is a +)
ftp://imall.iteadstudio.com/IM120411008_Iteaduino_v2.2/Document/DS_IM120411008_Iteaduino.pdf
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Offline newInRobotics

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #8 on: March 07, 2013, 04:49:20 AM »
OK, so apparently datasheet does not state bus power rating, nor if it's regulated or unregulated bus, in other words - this datasheet is sugar honey ice tea. One way to get an idea is to simply try to track where bus traces are going (if possible), if S goes straight to barrel connector, then it means it is not regulated voltage. If it goes to regulator then, it is regulated voltage and power rating can be determined by the regulator part number (if visible). The easiest way, probably, would be to build Your own power bus on a separate board.
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Offline SUTO the GTopic starter

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #9 on: March 07, 2013, 05:18:11 AM »
From this schematic can we figure it out? ftp://imall.iteadstudio.com/IM120411008_Iteaduino_v2.2/Document/SCH_IM120411008_Iteaduino.pdf
I am not very good at reading(understanding) schematics :(
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Offline newInRobotics

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #10 on: March 07, 2013, 05:30:35 AM »
Datasheet does not contain wiring diagram. I was talking about inspecting the actual physical device.
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Offline jwatte

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Re: Connecting 6V Battery For Servos to Iteaduino
« Reply #11 on: March 07, 2013, 11:03:07 AM »
There is no way that a regulator on a typical Arduino or Arduino clone will provide sufficient current for a medium-size servo. Typically, those regulators top out at 300-500 mA, and servos easily draw > 1A when actually moving against some load.

To power servos, you typically use an UBEC (Ultimate Battery Elimination Circuit.) The UBEC is connected to a battery (typically Lithium-Ion, or perhaps NiCad) and generates the right voltage for your servo -- typically 5V or 6V (get one that matches.) Separately, the battery should be connected to the barrel/vin connector on the Arduino. The Arduino will take care of its own voltage regulation, but you shouldn't depend on it to drive large loads like a motor, relay, etc. It's for LEDs and ICs only.

You *can* use two batteries if you want. 6V for the servo, and 9V for the Arduino, would work fine. Just make sure the connect the "-" of the two batteries together to generate a common ground, else you'll have problems getting signals from the microcontroller to the servo.
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