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Multiple batteries for lots of servo's

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Old 08-24-2004, 01:39 AM
  #1  
Peter G.
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Default Multiple batteries for lots of servo's

Iknow this topic must have been discussed before, but did not find it it my search.

I am building a B25 and will be running about 11 servo's. The flap servo seems to be drawing more juice than I like to keep those flaps up, not to mention that there are 10 more servo's. I would like to isolate one or more servo's to their own power source. I am told I can put the servo on a "y" harness and clip the power return wire so as not to drain the receiver battery should the servo drain it's own on the "y". Is this right?. I know I could also run two receivers, but what are the pro's and con's to these systems?

Any help would be appreciated.

Thanks Peter
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Old 08-24-2004, 06:45 AM
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WilsonFlyer
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Default RE: Multiple batteries for lots of servo's

I'm sure you will get some replies here... some good and some not so good.

This topic has been discussed ad-nauseum especially in the Giant Scale forum. I would take a look in there before I did anything and read how we do things on the big-birds. There are a thousand options, not the least of which is why is that ONE servo seemingly drawing so many amps when the others do not.
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Old 08-24-2004, 12:10 PM
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Peter G.
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Default RE: Multiple batteries for lots of servo's

Thanks I will look in the giant scale forum, I did a search in several forums but it seem s I don't have much luck with searches. I do not know if a search is forum specific or if it is RCU wide.
Any way thanks again.

Peter
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Old 08-24-2004, 04:58 PM
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BBW Walt
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Default RE: Multiple batteries for lots of servo's

You might check into an isolator. I have been running the I4C unit with execellent results. It will do what your asking, http://www.i4cproducts.com/
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Old 08-24-2004, 07:49 PM
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Default RE: Multiple batteries for lots of servo's

Indeed.

I run Isolators on ALL my GS's and wouldn't fly without them. There are more expensive options and cheaper alternatives but all in all; I think the Isolator is the best bang for the buck out there.
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Old 08-24-2004, 08:57 PM
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Default RE: Multiple batteries for lots of servo's

If you utilize a wye the batteries will simply share the loads, RX and servos.

You can power any servo indirectly by removing the power wires form the connector leaving the signal wire in place to the RX. Take the power wires removed from the connector and connect to an alternate power source. Many simply fabricate a power-buss for the servos with components readily available.

As mentioned above a servo isolator such as the i4c is a viable alternative. You might look at Emcotecs Servo Interface or Modelbau Powerbox as well, more expensive they but incorporate many more desireable features.

http://www.rc-electronic.com/html/en.../englisch.html

http://www.duralitebatteries.com/accessories.html
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Old 08-25-2004, 06:01 AM
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Default RE: Multiple batteries for lots of servo's

ORIGINAL: mglavin


You can power any servo indirectly by removing the power wires form the connector leaving the signal wire in place to the RX. Take the power wires removed from the connector and connect to an alternate power source.
can this be done without both power sources sharing a common ground?


dave
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Old 08-25-2004, 10:28 AM
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Default RE: Multiple batteries for lots of servo's

ORIGINAL: ZAGNUT

ORIGINAL: mglavin


You can power any servo indirectly by removing the power wires form the connector leaving the signal wire in place to the RX. Take the power wires removed from the connector and connect to an alternate power source.
can this be done without both power sources sharing a common ground?


dave
He might for some strange reason get away with it.
You should just remove the + wire connection and leave the - in place to provide a return for the signal.
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Old 08-25-2004, 12:43 PM
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Default RE: Multiple batteries for lots of servo's

ORIGINAL: ZAGNUT

ORIGINAL: mglavin


You can power any servo indirectly by removing the power wires form the connector leaving the signal wire in place to the RX. Take the power wires removed from the connector and connect to an alternate power source.
can this be done without both power sources sharing a common ground?
I neglected to offer that a common ground or the negative wire should be shared with the RX and auxillary power system.

George Steiner offers a simple solution for power buss needs and information on page #78 in the August 2003 issue of RCM...
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Old 08-25-2004, 02:13 PM
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Default RE: Multiple batteries for lots of servo's

Ok ....... I am confused ( nothing unusual here ) . Can I cut the power lead from the RX and leave the "y" with the power for that particular servo. This would leave both the signal wire and the ground wire intact and cause the servo to only draw power from it's own battery pack.

Has anyone done this?

Thanks Peter
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Old 08-25-2004, 03:59 PM
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Default RE: Multiple batteries for lots of servo's

ORIGINAL: Peter G.

Ok ....... I am confused ( nothing unusual here ) . Can I cut the power lead from the RX and leave the "y" with the power for that particular servo. This would leave both the signal wire and the ground wire intact and cause the servo to only draw power from it's own battery pack.
One thing you'd have to be aware of is that if the receiver battery voltage drops much below the voltage of the battery used to drive the servos then the logic pulse may not be of sufficient amplitude to reliably operate the servo.
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Old 08-26-2004, 11:13 AM
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Default RE: Multiple batteries for lots of servo's

ORIGINAL: Peter G.

Ok ....... I am confused ( nothing unusual here ) . Can I cut the power lead from the RX and leave the "y" with the power for that particular servo. This would leave both the signal wire and the ground wire intact and cause the servo to only draw power from it's own battery pack.

Has anyone done this?

Thanks Peter
Yes you can do this. I don't know if anyone has tried it.
Note xjets's caution. This can happen with the standard battery configuration. If you remove the battery drain of the servos, a standard pack can run a receiver long after the servo batteries are drained,however
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Old 08-27-2004, 08:04 AM
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Default RE: Multiple batteries for lots of servo's

Yes, just break (cut) the positive wire between the servo(s) and receiver and connect the servo power supply to the servo. You must keep the ground and signal wire intact between the servo(s) and receiver. In short, all grounds for all power supplies are always connected. The positive lead of the servo power supplies goes only to the servo(s) powered seperately but the negative lead of the servo power supply is common with all other negative leads in the system.
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Old 08-27-2004, 02:07 PM
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Default RE: Multiple batteries for lots of servo's

You guys are making this too hard...Just get another switch harness, and plug it into the RX in an open port...then you have 2 seperate switch/battery circuits...if a switch or battery fails, youre covered...I run my Comp ARF 2.6M this way..
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