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Old Oct 22, 2008, 03:00 PM
Registered User
Cut Off, LA
Joined Mar 2007
76 Posts
Question
Bec

I need a little help I am putting togather a twin engine twin speed controller and 2 battery set up. Should I use the BEC or should I put seperate batteries for the receiver? I already know I must disable 1 bec wire on one speed controler for this set up. Please give me all the pros and cons Thanks
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Old Oct 22, 2008, 03:06 PM
Grumpa Tom
Kmot's Avatar
United States, CA, Los Angeles
Joined Sep 2003
22,899 Posts
Look here, lots of info:

http://www.rcgroups.com/forums/showthread.php?t=783582
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Old Oct 22, 2008, 04:12 PM
apprentice shipwright
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Little Rock, AR
Joined Sep 2005
112 Posts
Don't know if this is mentioned anywhere in Ghost's thread, but this is something you may want to consider:
I have a two-motor / two ESC setup. Each one of the ESC's has a BEC as well. In order to protect the ESC's and motors from getting fried I have placed a 10A fuse in line with each of the ESC's.
The only drawback to doing this is that if the fuse leading to the ESC with the enabled BEC blows you lose power to your motor, but ALSO to your receiver, servos,... etc.
For safety sake, I decided to add an additional BEC connected directly, without a fuse, to the battery. This BEC (or additional small battery) is only for the receiver and servos. That way, if I do lose one of the fuses to one of the motors (and ESC), I still have a working receiver and servos to make it back to shore on one motor.
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Old Oct 22, 2008, 05:14 PM
Old wreck in Milwaukee
Prins Willem's Avatar
United States, WI, West Allis
Joined May 2007
3,661 Posts
If weight or space is an issue then use the BEC. My models all are large enough to easily accommodate a receiver pack. In a FE you might not want or be able to use a receiver pack.

I don't know if this still applies but in the olden days(early 90's) when I was involved in car racing, on BEC the battery level would drop low enough for the receiver to stop working while the motor would still run. Saw more than one car hit the wall due to that little glitch.
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Old Oct 22, 2008, 05:39 PM
Registered User
Joined Nov 2005
1,617 Posts
I'm running a 5cell Rx pack(350mah) in my 'no step 1' Fe boat. I do have to recharge after about 10minutes runtime (should be ok for 3 heats (or about 2.5 miles))
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Old Oct 23, 2008, 05:33 AM
Is life for real?
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Almere The Netherlands
Joined Sep 2006
1,320 Posts
In tweaking with my latest project I came up with these Ubec systems: http://www.elemodel.com/shopen/html/product_1139.html I've noticed that it seem to work with the steering servo. When turning it entices the ESC to give more "gas" which is excellent, in turns you loose some power and it seem to compensate for that . Boo
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Old Oct 23, 2008, 09:34 AM
no wings any more, just dust!
Ghost 2501's Avatar
stoke on trent
Joined Oct 2004
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on the diagrams, there are fuses marked (green spot) between motor and esc,and between esc and battery
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Old Oct 23, 2008, 10:40 AM
Registered User
Ontario, Canada
Joined Feb 2005
297 Posts
Battery Eliminating Circuit

Can anyone tell me why you need a BEC. I have run twin motors with twin ESCs and never used a BEC. Am I missing something?
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Old Oct 23, 2008, 11:18 AM
no wings any more, just dust!
Ghost 2501's Avatar
stoke on trent
Joined Oct 2004
8,052 Posts
fatboy, the term BEC comes from the aeromodelers, who in the interest of saving weight, started to use just one battery pack, rather than a seperate pack for the motors and a seperate pack for the radio gear, so by going to a BEC system, you have eliminated the battery pack used for the radio.
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Old Oct 23, 2008, 06:25 PM
Old wreck in Milwaukee
Prins Willem's Avatar
United States, WI, West Allis
Joined May 2007
3,661 Posts
Quote:
Originally Posted by fatboy999
Can anyone tell me why you need a BEC. I have run twin motors with twin ESCs and never used a BEC. Am I missing something?
In aircraft and racing vehicles (cars & boats) excess weight is a killer. The BEC takes the receiver pack out of the equation entirely. The downside is like front wheel drive. Everything is centralized, dead battery no anything else, fried ESC same story. I have a couple of FE boats using BEC but I never leave the house without a tug for rescue work. I have trust issues.
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Old Oct 23, 2008, 10:59 PM
Registered User
Cut Off, LA
Joined Mar 2007
76 Posts
I have enough room so I will put a seperate battery pack. Thanks
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