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Rx battery question

Old 01-18-2009, 09:36 AM
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seahwk95
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Default Rx battery question

Quick question for you guys: I'm assembling one of the new 40 size GP Escapades. This is my first plane to use dual aileron servos. I've used 4.8v (1100mah) RX batteries for all my other planes. Should I go to a 6V if using dual ailerons with the extra load of dual servos? The receiver is the 7 ch 2.4 futaba (r607fs).
Thanks
Old 01-18-2009, 09:56 AM
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craigteffe
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Default RE: Rx battery question

Its up to you. Both will do the job the 6 volt will speed up the sevos and give you more torque, the 4.8 volt battery will do the job though.
Old 01-18-2009, 10:28 AM
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dignlivn
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Default RE: Rx battery question



The 4.8 should be fine. Make it a point to
check the voltage before each flight, with
a loaded voltmeter.

Bob
Old 01-18-2009, 10:29 AM
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RCKen
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Default RE: Rx battery question

The battery you are using is plenty for this plane. The Futaba FASST radios do not suffer from low voltage reboot like the JR/Spectrum radios, so that's not an issue.

Ken
Old 01-18-2009, 06:51 PM
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seahwk95
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Default RE: Rx battery question

Thanks for the input guys. I do check the voltage under load after 2 flights and charge if necessary.
Old 01-18-2009, 08:15 PM
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CGRetired
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Default RE: Rx battery question

Pick up a voltwatch and install it. You can either plug it into a vacant RX channel or Y one of your used channels to accomodate it. It will do several things for you. It will give you a quick glance of your receiver charge (under load), it will give you an indication of binds in linkage, and it willl give you some peace of mind for the overall receiver/servo installation. It's a real worthwhile way to spend $11.99 (Tower Hobbies) you could make.

http://www3.towerhobbies.com/cgi-bin...&I=LXHDJ2&P=ML
Old 01-18-2009, 09:25 PM
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Charlie P.
 
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Default RE: Rx battery question

Remember: 6V will give you more torque but 25% less flight time in the same mAh rating.

I set up my 27% Ultimate (with dual rudder, dual elevator and four aileron servos) at 4.8v with 69 oz-in servos and never look back.
Old 01-19-2009, 06:56 AM
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CGRetired
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Default RE: Rx battery question

Yeah, you won't need any more than standard servos, no high torque, no digital, simple $10 servos will work just fine.

http://www3.towerhobbies.com/cgi-bin...&I=LX0929&P=ML

or

http://www3.towerhobbies.com/cgi-bin...&I=LXH288&P=ML

or any other standard servo. Just remember that you are using two servos (dual aileron setup) where other models, such as trainers, or others with one servo in the center. That's twice the torque. Granted, that's twice the current draw, but that amount is really ok, provided you are prudent in your setup (see below) and care of your battery packs.

As for battery packs, well, I use Spektrum and try to keep away from that reboot threshold, so I use 1200 mah 6 volt packs and they work fine. However, as said, the 4.8 volt packs, of the capacity you are asking about will work just fine.

The excessive current draw comes into the picture is when the control surfaces and throttle linkage is setup with any kind of a bind. This is especially true for the throttle. Binding usually occur when you have more servo movement than needed to operate the throttle to full open and fully closed. The servo can tend to move beyond the end stops and this will cause a bind and excessive current draw.

There is where the voltwatch comes in handy. You connect it normally, then exercise each servo, one at a time, (all surfaces and throttle) and check for excessive current draw (pushes the LED's toward the red). Normally, there will be some movement of the LED's into the yellow, which, as I said, is normal. But, if one of the servos reacts (pushes the Voltwatch LED's toward the red) more than any of the others, well you may have a linkage bind and should find it, remove it, then retest it. It may not go fully to the red, but tends to move toward the red (of course, as the battery gets drained, it will tend to go toward the red so do any testing with a fully charged battery).

Once all binds are removed and all survaces and throttle operate without any binds, you are good to go and should get good service out of that battery you selected. This is a very worthwhile test and when done right, you will have really good battery endurance for several flights per battery charge. What's nice about Voltwatch is that it will give you a "loaded" indication of your battery condition. If you take a glance at it before and after each flight, you will get those warm-fuzzy feelings that all is good and it will let you know (visually) that it's time to stop flying and put the battery on the charger.

If you want more information, any help, for checking and removing binds, let us know.

CGr.

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