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Using Two Receiver Batteries

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Old 11-24-2002, 09:08 PM
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martinjpainter
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Default Using Two Receiver Batteries

I would like to put two receiver batteries on one model. I am fitting four digital servos plus various other servos; I would like to run the four digital servos on one battery (bypassing the receiver) and run the rest of the system (including the receiver) on the other battery. I think someone sells a lead especially for the job, but I cannot remember where I saw the advertisement. Can anyone help?
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Old 11-24-2002, 11:26 PM
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Default Using Two Receiver Batteries

Try this link:
http://www.electrodynam.com/cgi-loca...839+1052295881
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Old 11-25-2002, 04:16 PM
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Default Using Two Receiver Batteries

Thanks for the response.
That is not the product I mind, however it will do the job. The item I had in mind looked like a Y Lead. I know I could use a Y lead and remove the red wire but I think this lead allowed up to four servos to be fitted, similar to the device above,
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Old 11-26-2002, 05:14 AM
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Default Re: Using Two Receiver Batteries

Originally posted by martinjpainter
I would like to put two receiver batteries on one model. I am fitting four digital servos plus various other servos; I would like to run the four digital servos on one battery (bypassing the receiver) and run the rest of the system (including the receiver) on the other battery. I think someone sells a lead especially for the job, but I cannot remember where I saw the advertisement. Can anyone help?
This is an interesting idea. What is the purpose of splitting the digitals from the analog servos? Just curious, as I've never heard of one doing this before.

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Old 11-26-2002, 08:04 AM
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Default Using Two Receiver Batteries

The idea is to stop putting the current through the receiver for the high drain servos. The digital servos use a lot more current than standard servos. A lot of the receivers were designed before digital servos were readily available and may struggle when the extra loads are being placed on them.

I am just being extra cautious. I have not experienced any problems but I am trying to pre-empt them.

The only other time I have used two battery packs is on my Kyosho Corsair ( http://www.mjp.co.uk/model%20aircraf...air/index.html ) where I have a separate pack for the retract servo. This is incase the retracts foul when in the up position and cause the retract servo to stall and drain the receiver pack in flight. This way I would only loose the use of the retracts opposed to control of the model.
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Old 11-26-2002, 12:30 PM
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Default Using Two Receiver Batteries

John look at the Multiplex IPD 12 reciver it is already desiigned to isolate servo groups and take two receiver packs. It is diode protected to make sure to handle the power managment properly.
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Old 11-26-2002, 02:15 PM
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Default Using Two Receiver Batteries

Originally posted by martinjpainter
The idea is to stop putting the current through the receiver for the high drain servos. The digital servos use a lot more current than standard servos. A lot of the receivers were designed before digital servos were readily available and may struggle when the extra loads are being placed on them.

I am just being extra cautious. I have not experienced any problems but I am trying to pre-empt them.

The only other time I have used two battery packs is on my Kyosho Corsair ( http://www.mjp.co.uk/model%20aircraf...air/index.html ) where I have a separate pack for the retract servo. This is incase the retracts foul when in the up position and cause the retract servo to stall and drain the receiver pack in flight. This way I would only loose the use of the retracts opposed to control of the model.
If that is the only reason, you shouldn't worry. Its common to see 40% airplane with 9 digital servos, and a couple analog servos, all running through one or two receivers. A few people have tested the receivers buy running 10amps sustained, and 20amps intermittent, and neither receiver had a failure.

My thoughts, for what they are worth, would be that you would add more unnecessary complexity, and more failure points, to offset a failure that has yet been unsubstantiated. To my knowledge, I have never seen a receiver failure discussed on all the forums I have been following (IMAC, IMAA, GSAL, RCU, Newsgroups) that was caused by excessive current. I have also seen single receiver planes fly with dual 2700mah packs, and 8 or 9 digital servos for season after season without any issues. If those planes can handle 9 servos without failure, you should feel fairly comfortable with running only 4 digitals.

The situation with the retracts is a good use of the technology and methods. I could easily see a failure of that sort taking the pack down. I had something similar in my 40% Giles, with a rudder servo that failed, stuck hard at neutral, and the other servos (ganged servos on the rudder) were fighting against it to try to move it. It drained one of my fully charged packs during one 10 minute flight. I almost lost the airplane. Luckily, I was running dual receivers, and the other receiver/battery pack was untouched. I was fortunate.

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Old 11-26-2002, 02:49 PM
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Default Using Two Receiver Batteries

I meant to include this in my last post, but forgot.

The person that did the test ran 10amps for a few minutes. If I remember correctly, it was to one set of plus-minus pins on the receiver, and out another set of pins. The person that ran the 20amp test, only ran the 20amps for a number of seconds (10 or 15 I think).

Another data point. A lot of the giant scale pilots flying the 40% or so sized airplanes also use voltage regulators when using Lithium batteries. These regulators are typically rated at 10amps maximum current. Its safe to say then that a 10amp load isn't common, or at least the maximum peak current, and not sustained, or it would have shown up in flight tests as poor performance. The 10amps is also spread across several connectors to the servos, but comes from one or two sets of pins from the batteries depending on a single or dual battery setup.

When my rudder servo failed on my Giles, the stalled servo was measured as pulling just over an amp. 9 stalled servos would pull 9amps sustained. 4 servos running normally will hardly pull an amp total, and all 4 stalled would still only pull 4amp. Still within reasons based on demonstrated usage.

Hope this all helps.
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Old 11-26-2002, 08:00 PM
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Hi,
I have received an e-mail asking me how I wired the retract servo with a separate battery pack on the Corsair.
The answer is to use a Y-Lead. Remove the red pin from the plug (opposed to the sockets) of the Y-Lead and either tape it up or protect it with heat shrink. Then simply plug the Y-Lead into the retract channel on the receiver (which only has two pins). Then plug the retract servo into one of the Y-Lead sockets and the other battery pack into the other Y-Lead socket. If you require a switch (very advisable) then connect the switch between the Y-Lead socket and the other battery pack.
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Old 11-26-2002, 08:20 PM
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Default Using Two Receiver Batteries

Originally posted by martinjpainter
Thanks for the response.
That is not the product I mind, however it will do the job. The item I had in mind looked like a Y Lead. I know I could use a Y lead and remove the red wire but I think this lead allowed up to four servos to be fitted, similar to the device above,
You might want to look at this. It lets you use anything you want and isolates everything.
http://www.geocities.com/roger_forgues/batteries.html
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Old 11-27-2002, 08:19 AM
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Thank you for all of the responses
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