The BEC output capacity is decreased as input voltage is increased.
voltage rating along with the output.
The Castle BEC’s output voltage
can be programmed to match your
The primary concern comes when
using large packs in series to attain 10S
or 12S motor power. The input wires
to the BEC must be connected to the
“most negative” side of the LiPo packs.
That can be confusing, but if you
always ensure the negative wire from
the BEC goes directly to the negative
wire of the series connection (where
the black wire from the ESC also
connects) and the positive wire goes to
that same pack’s positive side, you’ll be
fine. This keeps the voltage within the
range of the BEC and most important,
prevents a dead short from taking out
an expensive ESC.
Carefully study the Castle Creations
diagram and be sure you understand
my explanation. This diagram depicts
my Edge HV ESC, which doesn’t
have an internal BEC, so it says not to
disconnect the red wire. The diagram
depicts the best way to wire an
external BEC regardless of brand, but if
your ESC has an internal BEC, be sure
to disconnect the red wire.
If nothing else, remember that the
black wire from the BEC and the
black wire from the ESC should be
connected where they meet the black
wire from the first pack.
The primary benefit is that you
won’t burn anything up, and the
secondary benefit is when you’re
connecting the two packs in series to
arm your system.
When the first pack is connected, the
BEC will activate and provide power
to your receiver. This will ensure the
receiver is powered before the second
battery is connected and the ESC