🔋 BEC
Battery Eliminator Circuit — a small voltage regulator (usually in the ESC) that powers the receiver and servo from the main pack, so you don't need a separate receiver battery.
What it actually does
The BEC — Battery Eliminator Circuit — is the part of the ESC that steps the main pack voltage down to the five or six volts the receiver and servo need. Its name comes from what it eliminated: the separate receiver battery pack that older models had to carry.
In practice
BECs are rated in amps, and a powerful, fast servo can ask for more than a modest BEC can supply. When it cannot keep up, the receiver browns out and the car simply stops responding for a moment — usually at the worst time. High-current servos may need an external BEC.
Worth knowing
Intermittent loss of control under hard steering, with everything working fine on the bench, is the classic BEC symptom. It gets misdiagnosed as radio interference constantly.