Banner Ad 1

Why BEC?

Place for general submarine conversation

Postby Carter » Mon Jun 30, 2003 11:03 pm

Is BEC necessary for subs? Consider the following scenarios:

1) I am flying a radio control electric airplane and the batteies are running out of power. BEC shuts the motor off, insuring I have enough power to control the servos as I glide the plane in for a landing.

2a) My sub is thirty feet away from me and I notice it is slowing a bit. BEC cuts in, shuts off the motor, and I have rudder, dive planes and ballast control, but no power to drive the sub back to shore.

2b) Without BEC, I notice the sub is slowing down, and I turn the boat to shore and drive it in as the battery dies out.

Why is BEC desirable in submarines?
Carter
Registered User
 
Posts: 56
Joined: Fri Feb 21, 2003 11:11 am
Location: Oz

Postby Skip Asay » Mon Jun 30, 2003 11:50 pm

"Is BEC necessary for subs?"

1. Consider what BEC stands for - Battery Eliminator Circuit. When you consider just how tight most pressure hulls are, where would you put an extra battery?

2. Do you have any idea how frustrating it can be to find out AFTER you get to the lake that you charged the transmitter and main drive battery but you forgot to connect that 3rd charger?

3. Generally speaking, your airplane scenario isn't appropriate. At its slowest speed (when using a speed control), the airplane motor is drawing much more than a sub draws at its highest optimum load. Put just a 10 amp load on a 1700 mAh nicad and look at the voltage drop at the battery. That same load on a battery that's at end of charge won't have enough to drive the receiver/servos.

4. While there are some boats running on 6 volts, most are 7.2 volt and higher. Since receivers are designed to run on 5 volts, when you see your boat running noticably slower, there's still plenty of juice left to run the motor (at slow speed) as well as the receiver/servos to get you back to shore.

But, as valid as that question is, it seems you're thinking that it's the BEC which cuts the power at a certain discharge level. Not true. By itself, BEC takes the place of the receiver battery. (See #1 above) There's another circuit which senses voltage and cuts power to the motor when a certain threshold has been reached.

Skip Asay
SubTech
The U.S. of A - Land of the Free BECAUSE of the Brave
Skip Asay
Registered User
 
Posts: 255
Joined: Fri Feb 21, 2003 11:04 pm
Location: Sanford, NC

Postby Carter » Tue Jul 01, 2003 2:05 pm

Ah, I see. Thanks. CK
Carter
Registered User
 
Posts: 56
Joined: Fri Feb 21, 2003 11:11 am
Location: Oz


Return to General

Who is online

Users browsing this forum: No registered users

cron