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Old Jan 19, 2012, 10:34 PM
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United States, FL, Lehigh Acres
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Question
where are you guys placing your separate receiver pack?

wheres a typical location to place a receiver pack? i have a lifesource pack.

im still learning and have learned alot since joining this site! i am a bit confused as to whether i should power my radio gear from a bec or a receiver pack. im hearing becs failing on some people. what are the ups & downs on becs and receiver packs? any info is big help for me!

sbach 342 60" ep
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Last edited by out of stock; Feb 19, 2012 at 07:14 PM.
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Old Jan 19, 2012, 10:54 PM
Balsa addiction since age 3
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Upstate NY
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Originally Posted by out of stock View Post
im still learning and have learned alot since joining this site! i am a bit confused as to whether i should power my radio gear from a bec or a receiver pack. im hearing becs failing on some people. what are the ups & downs on becs and receiver packs? any info is big help for me!

sbach 342 60" ep
A BEC can work very well - depends on lots of factors. Some are better than others. Some are linear regulator based designs and significantly reduce in current capacity as the number of cells goes up. Some are "switching" and generally can tolerate more cells but "might" introduce electrical interference. Some servo's require more power than others for the same "general" characteristics. Digital servos for example (I don't use) seem to be more power hungry but then again some of the cheap Chinese servos also seem power hungry.

Many of the "good" ESC's have switching BEC's that can handle 3A draw (vs 2A for linear at 3S and less at 4S). These are generally the ones I use and I have had no failures or issues (other than forgetting to validate cutoff voltage when first getting into LiPos).

It depends on the plane you are flying, how you fly it (fast, 3D), the number of servos (load) and how smooth your control setup is. I see people complaining about their BEC's failing, but there seems to be a good correlation with too much load on the BEC, inadequate cooling and or too many cells in their pack and a linear regulator that is not rated to handle that load. When in doubt, test it (all electric flyers should have a voltage, current meter that can be installed inline to evaluate at least that the prop is not drawing too much current). If not confident, use a separate battery or higher rated standalone BEC - it is not worth losing a plane.

For what it is worth, ALL of my planes count on the built in BEC. Most are gliders so the in flight load is very low on the servo. I run 6 small, quality analog servos on a 3A switching BEC with no worries but on sailplane. I would NOT do this with a conventional power plane where the servos work much harder. I think you will find that many people use 3 or 4 servos with a switching BEC that is rated at 3A.

Just bear in mind that the separate receiver battery, if not charged, can also lead to catastrophic failure.

I am sure others will pipe in!

Scott
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Old Jan 19, 2012, 11:47 PM
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If you are flying small foam park flyers, you have no choice but use a built in BEC due to limited pay load and space.

If your plane is large, it is safer to use separate battery for receiver and servo.
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Old Jan 20, 2012, 10:18 AM
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I would fly a 60" WS and larger airplane only with a separate receiver pack. These use standard size servos and at least 5S packs. Not worth risking it to a BEC when there are good receiver packs (like 2S LiFe).

Ivan
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Old Jan 20, 2012, 10:56 AM
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ivan, john and scott thank you very much. What's a good receiver pack? ?
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Old Jan 20, 2012, 11:08 AM
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I'm using this one or this one if the first one is not in stock and I need one badly.

There are also some on HK but they often are not in stock and takes a minimum of 10 days to get items from HK when they are all in stock.

When using 2S LiFe make sure you use servos capable of 6V. Some servos are rated for 4.8V only and may not survive being powered by a 2S LiFe.

Ivan
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Old Feb 19, 2012, 07:16 PM
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yup thats for sure
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Old Feb 19, 2012, 08:05 PM
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OK, nobody mentioned where to put the receiver battery.
It's your bargaining chip when adjusting the CG. When you're ready to balance the plane, then position the battery to help get the balance as close as possible before adding any extra weight to the model.
Pete
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Old Feb 19, 2012, 08:27 PM
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Originally Posted by pilotpete2 View Post
OK, nobody mentioned where to put the receiver battery.
It's your bargaining chip when adjusting the CG. When you're ready to balance the plane, then position the battery to help get the balance as close as possible before adding any extra weight to the model.
Pete
definitely makes sense. and by the way lol i just updated this thread lmao im sorry. (your like, what the? all this information and nothing about the main topic?) thanks mate! good answer!
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Old Feb 19, 2012, 08:30 PM
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I typically place the receiver battery pack under the fuel tank in a airplane. You normally want everything forward as much as possible, to save on adding lead weight to the front of the plane to get the CG to come out correctly. But then it depends on the airplane too. Of course the small Life packs are fairly lightweight compared to Nicad or NMH packs, so it probably doesn't make much difference where you place the battery pack with them.

Now with Lipo packs, you probably want to have it in a location to allow you to remove it for charging separate from the plane. That way on the rare occasion something might go wrong the Lipo pack doesn't burn your plane up on you too.
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Old Feb 19, 2012, 10:05 PM
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is it possible to use a 6" extension from liFe pack to Rx? i mean, i tried but the Rx barely powers up. at first i thought it was the liFe pack that was out of charge but when i removed the extension and plugged the liFe directly, my radio system came to life.

yes its lightweight so maybe it wouldn't make a difference. i hope lol
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Old Feb 19, 2012, 10:08 PM
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oooop's! double posted. sorry!
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Old Feb 19, 2012, 10:12 PM
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Your servo extension is no good. I use servo extensions for the battery pack all the time but the ones I use are the ones with thicker wires (22 AWG). "Standard" servo extensions use 26 AWG which is much thinner and not capable to carry power to 4 or more servos.

Ivan
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Old Feb 22, 2012, 10:58 PM
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Originally Posted by ivanc View Post
Your servo extension is no good. I use servo extensions for the battery pack all the time but the ones I use are the ones with thicker wires (22 AWG). "Standard" servo extensions use 26 AWG which is much thinner and not capable to carry power to 4 or more servos.

Ivan
actually that is very true. thanks ivan.
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