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HelicopterBeginners Corner › What is a bec??
07-12-2008 01:19 PM  9 years agoPost 1
ronmad02

rrApprentice

Toledo, Oh - U.S.A.

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Ok I have a a t-rex 450 and just got a swift16. The t-rex is running 3s 2100 battery with the align esc. the swift has a cc45hv on it and i am going to run a 6s setup. Do i need a bec? and what does it do? I was thinking of running a rx pack on the swift. Would that take the place of the bec?

Thanks for the help Ronmad02

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07-12-2008 02:30 PM  9 years agoPost 2
lrogers

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Mobile, Al

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BEC stands for battery eliminating circuit. Speed controls so equiped reduce the propulsion battery voltage down to power the on board electronics saving the weight of a separate receiver battery. At some point (not sure what is the cut point) the voltage of the propulsion pack is to high for a built in BEC to be used and you have to go with a separate pack or a separate BEC.

I have a couple of friends flying larger electrics (Swift and T-Rex 600) and niether are using BEC's.

Larry Rogers - R/C Helicopter Pilot

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07-12-2008 03:20 PM  9 years agoPost 3
zo6

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Ohio USA

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Trex 450 ok w/o add-on regulator.....the 6S will need a regulator. I like the Western Robotics HV stuff. Pricey, but best quality around. Stay away from CC on regulators when needing high voltage and amp draw.

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07-12-2008 03:41 PM  9 years agoPost 4
bigdog714

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Rochester, MN U.S.A.

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The SportBEC is one I recommend, its non linear, meaning it maintans a constant 3.5amp output regardless of the voltage input. Its switchable from 5v to 6v and the ESC plugs into the BEC which plugs into the throttle port on the receiver which is important because I fly Spektrum, I don't have to wory about the pulse wire re-binding my RX.

They also make a version with lipo protection.

Just remember that the most important thing when looking for a BEC is that the amperage remains constant regardless of the input voltage, and dont go below 3amps.

I see you have CC45HV ESC, check out the new Gov. software, I use it on my 500 & 600 its awsome, just tell the ESC your desired head speed and the ESC does the rest.

MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
HD 500V2
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Avant 90E

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07-12-2008 03:46 PM  9 years agoPost 5
ronmad02

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Toledo, Oh - U.S.A.

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So for the swift I have to run a bec or use a rx battery pack? I will look into the bec you guys have recommened. And thanks for the heads up on the gov software. Is that from cc .

thanks ron

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07-12-2008 07:59 PM  9 years agoPost 6
bigdog714

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Rochester, MN U.S.A.

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A Bec is better than a 4.8v or 6.0v RX pack, they cant maintain a constant voltage, that why I use lipo packs. The Swift is a 550 class heli and can carry a 2S 2000mAh lipo. I prefer a a seperate battery for my electronics on my 600EP. I feel better knowing that my TX and RX are insink before I plug in the main pack.

Yes the Firmware is from Castle for the 45HV you have.

MD 800
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Ballistic 700
HD 500V2
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07-13-2008 02:04 AM  9 years agoPost 7
ronmad02

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Toledo, Oh - U.S.A.

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Ok I see I will still need to use a bec but use it with a 2s lipo witch is 7.4 volts and the bec will step it down. I agree the lipos are a better battery. So I will look at setting it up like that.

thanks

Ron

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07-13-2008 02:48 AM  9 years agoPost 8
bigdog714

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Rochester, MN U.S.A.

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You can soder the leads from the BEC to the battery conector with ESC leads and use the power from the main pack also, its just a little more dangerous, if your default settings aren't correct, or the ESC hasn't been properly calibrated, there's always a chance of motor start up, a 550 can f*#k you up. Besides weight isn't that important, for us regular pilots.

MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
HD 500V2
Hirobo 50E
Avant 90E

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07-14-2008 04:30 PM  9 years agoPost 9
MikeC

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Mosinee, WI

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I use a regular 4 cell 1400 mah NiCd pack on my Swift. Works just fine.

Mike

Century Swift, TREX 450, Blade MCX, Spektrum DX7

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07-14-2008 04:43 PM  9 years agoPost 10
ronmad02

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Toledo, Oh - U.S.A.

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With that mike you dont need a bec you just plug it into your batt on the receiver right?

I am only in the hover and FF stage right now I wont be in 3d or sport flying for some time now.

Thanks Ron

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07-14-2008 06:41 PM  9 years agoPost 11
MikeC

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Mosinee, WI

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Yes, just a 4 cell battery and a switch harness. Oh, and also a battery voltage monitor. At my level of flying (FFF and the occasional mild aerobatics) having a totally unchanging voltage to my servos (possible with a BEC) is unnecessary. Plus, I only have one pack for my Swift so I can top off my RX battery while waiting for my motor pack to charge.

Mike

Century Swift, TREX 450, Blade MCX, Spektrum DX7

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07-15-2008 12:23 AM  9 years agoPost 12
bigdog714

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Rochester, MN U.S.A.

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A 4 cell Nicd is twice the size and weight of a 2S 2000mAh lipo, and the voltage drops off fast, and so does your servo performance. As a new pilot there will be times you'll need to bail out, and without servo speed, your going down.

MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
HD 500V2
Hirobo 50E
Avant 90E

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07-15-2008 04:01 AM  9 years agoPost 13
MikeC

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Mosinee, WI

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A 4 cell Nicd is twice the size and weight of a 2S 2000mAh lipo, and the voltage drops off fast, and so does your servo performance.
I don't care! And neither does the average flyer! In fact I guarantee the average flyer (not talking extreme 3D here just average flying), will not be able to tell the difference between a 4 cell NiCd and 2 cell LiPo!

Mike

Century Swift, TREX 450, Blade MCX, Spektrum DX7

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07-15-2008 11:20 AM  9 years agoPost 14
bigdog714

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Rochester, MN U.S.A.

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Flying Spektrum with 4.8v Nicd doesn't make you nervous? You do know that at 3.27v a Spektrum RX shuts down. Once a gain its not just about the weight, its piece of mind, battery and BEC around $60, heli over a $1000, piece of mind, priceless, and cheap!!!!

MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
HD 500V2
Hirobo 50E
Avant 90E

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07-15-2008 02:12 PM  9 years agoPost 15
MikeC

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Mosinee, WI

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Flying Spektrum with 4.8v Nicd doesn't make you nervous?
Not in the least! We've been flying with NiCd receiver packs for decades! Other than weight, the NiCd battery is one of the best choices out there for a rx pack. Contrary to popular belief memory is not that much of a problem. They don't bleed energy like a NiMH and deliver much better voltage under load than a NiMH. And they don't explode like a LiPo if you don't treat them just right.
You do know that at 3.27v a Spektrum RX shuts down.
Why would I care if the Spektrum rx shuts down at 3.27V when my rx pack is never going to be that low. If I was running 2500 mah "AA" size cells I'd worry which is why I never run anything less than sub C size cells with NiMH.
Once a gain its not just about the weight, its piece of mind
Piece of mind is why I won't use a BEC on my larger models. A BEC is a piece of electronics which like any other piece of electronics can fail at any time for any reason or no reason at all. A battery and switch harness (both of which are checked and/or replaced regularly) is about as reliable as it gets.

Century Swift, TREX 450, Blade MCX, Spektrum DX7

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07-15-2008 03:47 PM  9 years agoPost 16
nivlek

rrProfessor

Norfolk England

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A 4 cell Nicd is twice the size and weight of a 2S 2000mAh lipo,
True , but it also provides a very clean supply voltage , generates no rf noise , and has less points of failure .

At the end of the day , it gets dark .

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07-15-2008 10:21 PM  9 years agoPost 17
bigdog714

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Rochester, MN U.S.A.

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Like I said before, its you heli do what you will. Someday you might want to joine the rest of us in the 21st century

MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
HD 500V2
Hirobo 50E
Avant 90E

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07-16-2008 05:07 PM  9 years agoPost 18
MikeC

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Mosinee, WI

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True , but it also provides a very clean supply voltage , generates no rf noise , and has less points of failure
Thanks. This shows that some of us have a clue and some of us don't!
Once a gain its not just about the weight, its piece of mind, battery and BEC around $60,
You don't get piece of mind from a piece of technology that can, and probably will, eventually fail. I've been flying RC for almost 30 years and have had a few crashes due to technology failing. One caused by a bad receiver, one from a BEC within an ESC, a near crash because of a bad gyro. I have never had a crash because of a battery or switch harness failure! Ever!

Century Swift, TREX 450, Blade MCX, Spektrum DX7

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07-16-2008 05:30 PM  9 years agoPost 19
Pistol Pete

rrProfessor

Seffner, FL

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@RONMAD02
I was thinking of running a rx pack on the swift. Would that take the place of the bec?
yes.

I use a Hydramax Ultra 1650mA NiMh.

I also use a Castle Creations P-80 with BEC disabled mainly due to using 6S. (red middle wire disconnected as per directions)

A voltage regulator is the alternative to not using a Rx batt. as it will regulate the voltage "down to" the level needed for the servos and especially the gyro.

The Swift wont cry about an extra 100 grams up front at all nor will it take away much flying time...(where talking a few seconds worth)

~~Enjoying the hobby one flight at a time~~

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07-16-2008 05:37 PM  9 years agoPost 20
nivlek

rrProfessor

Norfolk England

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Flying Spektrum with 4.8v Nicd doesn't make you nervous? You do know that at 3.27v a Spektrum RX shuts down. Once a gain its not just about the weight, its piece of mind, battery and BEC around $60, heli over a $1000, piece of mind, priceless, and cheap!!!!
What a pile of crap . I test switch mode power supplies all day , so no , having a regulator in my models gives me no peace of mind . A decent 4.8v nicad under flight loads will not drop to anywhere near the voltage where the receiver will shut down .
I doubt that any PCM receiver/digital servo would be working down at 3.3V , and they have worked fine on 4.8V nicads for years !

A decent nicad will be able supply more current than most regulators can and it won't cost as much as a regulator set up , but really its not about the price , it's about peace of mind .

At the end of the day , it gets dark .

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