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BEC or Reciever-battery ?

R/C Submarine modelers

Postby 65-1050534571 » Sun May 18, 2003 6:21 am

Hi,

What is your experience by eliminating the Rx-battery, using the BEC of the ESC in stead?

I am considering to eliminate my Rx-pack, using the 1 Ampere (continous) BEC of my ESC. I only have 2 Standard Servo in my Pat Henry with TAES BallastTank control.
However, I also use the Mini-pitch Controller, meaning that the elevator-servo is constantly working. Thus my concerns using BEC.

What are you using - BEC or RX-battery? And with how many servos?

Anders
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Postby Wheels » Sun May 18, 2003 9:59 am

Anders...On pumped ballast systems I always use a separate battery for the receiver and servos. The reasoning is if your drive battery which is 6 volts on this system goes low you will lose control of the radio. Using a separate battery will allow the ballast system and drive motor to function even at a reduce speed if you drain the main battery since it's a gel cell and not a NiCad. This way you can limp home. I've been there and almost lost a boat. That kind of tee shirt you don't need.

Jim Wheeler :D
Jim Wheeler....."Life is not measured by the number of breaths we take, but by the moments that take our breath away."
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Postby 65-1050534571 » Sun May 18, 2003 1:35 pm

But Jim - if the Drive motors of the Ballast tanks and the Propulsion are dead due to a low Battery, of how much help a perfectly functioning radio any way?

I plan to build in 2 x 6Volt/7,2 Ah Panasonics. This should give hours and hours of service..

Anders
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Postby Britt Boyette » Mon May 19, 2003 10:04 am

You can aways tell when you main batteries are going low as your top speed starts to slow down. My experence has shown that the demands of a 4 channel radio on a low main battery will crap out before the juice is all gone. I like to run the battery pack on the RX because the performance of you gear will be there even after the mains are gone instead of the other way around. In smaller WTC's like D&E's 3.0, I use Skips BEC. It seems to work better and can handle the demands. Some ESC's instructions tell you to use battery packs if you use more than two servos.
Britt Boyette

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Postby bo@ti » Sat Jun 14, 2003 8:23 pm

Anders wrote:Hi,

What is your experience by eliminating the Rx-battery, using the BEC of the ESC in stead?

I am considering to eliminate my Rx-pack, using the 1 Ampere (continous) BEC of my ESC. I only have 2 Standard Servo in my Pat Henry with TAES BallastTank control.
However, I also use the Mini-pitch Controller, meaning that the elevator-servo is constantly working. Thus my concerns using BEC.

What are you using - BEC or RX-battery? And with how many servos?

Anders

Don`t forget the "noise" generated with only one battery source used!
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Postby Tim Morris » Sat Jun 14, 2003 9:36 pm

if you use a speed control with a battery eliminator circuit, and the speed control is plugged into the reciever, which is in itself supplying power, then can you still plug in a 4.8 volt nicad pack into one of the open slots on the reciever (the one that says B) in addition to that and not exceed the voltage for the reciever? i use an airtronics VG600..

do you have to use diodes for this?
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Postby Ramius-II » Sun Jun 15, 2003 12:10 am

Hi Anders:
What makes a big difference is if you plan to use the two 6 volts batteries is series for 12 volts or in parallel for 6 volts at twice the current. If you plan to use the two batteries in parallel then you might consider a diode on each battery to isolate the batteries from each other. In any case, unless you plan to charge the batteries independently, the diodes will become a must during charging. Also, if one battery fails internally, the other battery will not be compromised. :(

As for your original question, the use of a BEC is fine for the purpose of keeping the receiver battery up. Having a receiver battery connected as close to the receiver as possible, means the receiver will have less noise to deal with coming from the main power as the battery is like the best filter you can have! :;): If you are completely against having a receiver battery then you will most likely need additional power filtering for the receivers power.

D.C. motors generate noise via the sparks produced by the motors brushes. This noise will vary according to the speed of the motor. The result is "nervous" (those that shake) servos.

What may be to your advantage is to consider two possible design alternatives. One design would be to change as much of the exsisting 6 volt system to a 12 volt system. I can assist with this if you like, I did this on my Typhoon. The other possible design would be to configure the second battery so it can be in parallel with the first or in series. Thus if both batteries are down to 3 volts, you still have 6! :D


My Best, Ed :D
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