When to use Internal vs External BEC
 

Still climbing the electrics learning curve.

A few questions:
1.) When do you have to use an external BEC vs the one internal on an ESC. Is it a hard fast rule that when your supply batter is over 12v (from the "Everything you wanted ..." eBook) you have to use external?
2.) Are there any ESCs that have internal BECs that can handle the full voltage range that the ESC can?
3.) When and ESC says BEC - OPTO, what does that mean?
4.) Pros/Cons of an SBEC vs UBEC vs ?BEC

Thanks

-Jorden

1.) When do you have to use an external BEC vs the one internal on an ESC. Is it a hard fast rule that when your supply battery is over 12v (from the "Everything you wanted ..." eBook) you have to use external? 2.) Are there any ESCs that have internal BECs that can handle the full voltage range that the ESC can?
Some ESCs with internal BECs are rated for >12v (I've seen up to 26v) but I'm never sure whether they mean the ESC can cope with the higher voltage as long as you don't use the BEC! (Castle do that.. 3s, with BEC, 4s or more, without).. if they have switching BEC they may be okay.. but not if linear. I can't see an internal BEC being able to reduce 26V down to 5v without frying something

3.) When and ESC says BEC - OPTO, what does that mean?
This means there is no BEC so you must use an Rx pack or a stand alone BEC to power the Rx and servos

4.) Pros/Cons of an SBEC vs UBEC vs ?BEC
SBEC may refer to SportBEC (brand name), or may simply mean switch-mode BEC, UBEC (UniversalBEC) is typically a stand-alone BEC like the Castle 10A but HK uses SBEC and UBEC indiscriminately in their advertizing. Stock BEC with linear mode is the simplest and most limited in terms of delivering power to servos etc. At high voltage input, linear BECs get a lot hotter than the switching ones.

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
http://www.rcuniverse.com/forum/m_7100376/tm.htm


Dr. K did a very good job of covering your questions. This e-book may help broaden your understanding.