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Post by Chris Reibert on Mar 10, 2012 0:37:56 GMT -4
I am throwing back and forth what Motor/ESC combo I want to put inside my new Chaos 600 I ordered. I want to keep it a 6s set-up and wondered what a BEC is and what the benefits are? Correct me if Im wrong but like in my Trex 550 that used a 22.2v 6s pack the ESC/BEC steps down the voltage for the electronics?? If so what is the benefit of running an external BEC? Control of your bird if the ESC craps out? Here is a pic of the ESC/BEC I used in conjunction with my Align 600MX I used in my Trex 550. I enjoyed the power and realiable. All input would be great, thanks guys. Attachments:
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Post by qmaverick on Mar 10, 2012 3:03:51 GMT -4
My knowledge is purely theoretical, don't own a big bird, but this is what I have come across...
The BEC on a ESC is limited on the Amps it can deliver, when you move the swash you have three servo's that start moving (the tail servo will move too, adding to the current draw), each servo draws an x amount of current. This current is quite high, especially with digital servo's, if your BEC cannot deliver, your Rx will not get enough juice and you'll get a brown out...
This scenario gets even worse if you use FBL with a FBL controller, the servo's will start/stop all the time resulting in an even bigger load on the BEC.
For the big birds it is recommended to run a battery with the ESC for powering the motor and a seperate battery with a powerfull enough BEC for powering the electronics.
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Post by Valkman on Mar 10, 2012 5:21:38 GMT -4
ESC can fail and IMO the bigger they are the more likely they fail and the more danger! If it fails you have no power to the motor OR the servos. Again, IMO, anything over 500 size should have a BEC or seperate power supply for the servos. I have the Turnigy BEC on my 450 and 600 and I have another on the way for my 500. I have about 20 flights on each with no issues but I fly fast sport so I dont put as much load on them as 3d. After each flight the BEC is barely warm. There is also a jumper on the units to change the servo voltage to 6 volts which I have both at. Heres a link to the 3 amp ( max 5 ) 450 BEC for 4.18 US www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=4319And the 5 amp ( max 7.5) for 15.56 US. www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6320Both get good reviews anywhere I looked. If your a stick banger maybe a seperate power source is the way to go like a LIFE battery.
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jombo
PARK FLYER
Posts: 63
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Post by jombo on Mar 10, 2012 11:49:41 GMT -4
this is the one i have and also on the 700. www.valuehobby.com/power-systems/speed-controller/hobbywing-switch-mode-ubec-8a-ultimate-bec-for-2-3s-lipo.htmlthe external bec frees up the esc to put all the power from the main battery to the motor . this also means less heat and more cooling for the esc. the smaller birds 450 and lower, your limited in space especially the 450 pro and 250. so i just use the esc with built in bec and just wing it and hope i dont overdraw the bec with digital servos . if you add up the draw on the digital servos your under the 3 amp limit but not if something jams .
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Post by Valkman on Mar 10, 2012 12:34:52 GMT -4
Have you seen the specs on the page for the Amps. First it says 8 amp 15 burst, then 5 amp 7.5 burst. It also say 2-3 cells input then 3-10 cells input then 2-4 cells!! If they cant be honest and tell you the specs I would just click elsewhere.
Edit.....it looks like it is 2-3 cells. Ok for the 450.
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drev
FUN FLYER
Posts: 198
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Post by drev on Mar 10, 2012 13:48:11 GMT -4
I was going to use the internal BEC in the Phoenixtech 100a ESC, but after some research I got a 6.6v 2s 3000ma LIFE pack for Rx power. Remove the power wire from the throttle harness & hook the LIFE pack directly to the Rx. Simple! Just make sure it's charged up before you go out to fly. Fly safe... Drev.
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Post by Valkman on Mar 10, 2012 13:52:25 GMT -4
3000mah! That will keep you going till spring lol. It seems to be the way to go if you fly hard.
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drev
FUN FLYER
Posts: 198
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Post by drev on Mar 10, 2012 14:10:54 GMT -4
I won't be flying hard, just going to take it easy at first. That battery was on sale at the time & needed some nose weight for proper CG, only running 6s for now (upgrades to come), + I can go out & not have to worry about Rx power for the day. Drev.
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Post by Dr. Evil on Mar 10, 2012 19:44:39 GMT -4
I always understood it as that by using an external BEC is like an insurance policy especially for anything on a 550 size heli and bigger. It was meant to supply the RX with power to be able to have control over your servos incase there is a "Brown out" by feeding off of the flight pack.
BTW, I am currently using the CC BEC Pro on my 600 and plan on using the same on my 550 as well as the 700.
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Post by Chris Reibert on Mar 10, 2012 23:00:56 GMT -4
Evil send me a link to the cc bec and how you installed it. Thx
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Post by Dr. Evil on Mar 10, 2012 23:07:12 GMT -4
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Post by Chris Reibert on Mar 12, 2012 13:17:41 GMT -4
Thank you guys. Ya Evil in gonna go with that same set-up Pictured above
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lee
PARK FLYER
Posts: 68
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Post by lee on Mar 27, 2012 10:08:39 GMT -4
I have the CC 10A BEC to put on my 600. Will that do, or do i need the CC Pro??
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Post by Valkman on Mar 27, 2012 13:28:16 GMT -4
That will do. That leaves 2.5 amps for each of the 4 servos which is plenty. They won't draw even 2 amps and I would say the wires going to the servos will melt with much more than that at constant load. I'm running 5-7.5 amp and it runs cold but I don't do 3d which would put more of a load on. Ask some of the guys at the field how many flights they get on their seperate "small" battery packs and do the maths!
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Post by Dr. Evil on Mar 28, 2012 8:48:18 GMT -4
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