Choosing A BEC
What Does a BEC Do?
A BEC’s job is simple but critical:
It steps high battery voltage down to a safe level
It powers your receiver, servo(s), gyro, and accessories
It must supply clean, stable voltage under load
If your BEC can’t keep up, your electronics will suffer — even if everything is “rated” correctly.
Peak Amps vs Continuous Amps (This Is Where People Get It Wrong)
🔴 Peak Amps
Short bursts only
Last milliseconds to seconds
Occur during sudden load spikes (hard steering hit, bind, impact)
Not sustainable
Peak amp ratings look impressive on paper — but they are not what your system runs on.
🟢 Continuous Amps (The One That Matters)
What the BEC can deliver all the time
Sustains steering under load
Keeps voltage stable
Prevents brownouts and resets
👉 Your RC runs on continuous amps, not peak amps.
If your system demands more current than the BEC can continuously supply, the voltage drops — and problems begin.
What Happens When a BEC Is Undersized?
An undersized BEC can cause:
Steering lag or weak return-to-center
Servo chatter or overheating
Receiver brownouts
Radio signal loss
Random reboots
Premature servo failure
These issues often get misdiagnosed as a “bad servo” — when the real issue is power delivery.
Why High-Torque Servos Demand More Continuous Amps
Modern high-torque servos (especially crawler and monster applications):
Pull high current even at low speed
Draw current continuously while holding load
Can spike AND sustain heavy amperage
A servo rated for high voltage means nothing if the BEC cannot maintain that voltage under load.
Voltage without current = instability.
Battery Voltage Also Changes Amp Capability
One important detail many people miss:
BEC output current changes based on input voltage
Higher output voltage = lower available current
Higher input voltage = more heat to manage
This is why BEC current ratings are often shown in charts, not a single number.
👉 A BEC rated at “15A peak” might only provide 7–10A continuous, depending on voltage.
How to Choose the Right BEC (Simple Rule)
Step 1: Add Up Your Load
Steering servo (main draw)
Receiver
Gyro
Accessories (winch, lights, fans)
Step 2: Focus on Continuous Amps
Choose a BEC whose continuous rating comfortably exceeds your total draw
Leave headroom (20–30% minimum)
Step 3: Match Voltage Correctly
Don’t run higher voltage just because you can
Match servo specs AND BEC capability
Waterproof ≠ Invincible (Still Important)
If you run crawlers, marine, or wet conditions:
Waterproof BECs protect electronics
But heat, load, and current limits still apply
Water protection does not increase amp capacity
Even waterproof electronics need proper power sizing.
The Shift RCS Philosophy on Power
At Shift RCS, we design and recommend setups based on real-world load, not marketing numbers.
Continuous current is king
Voltage stability matters
Headroom prevents failure
Proper power protects your investment
This is why we’re honest about how electronics actually behave — not just how they’re advertised.
Final Takeaway
Peak amps sell. Continuous amps perform.
If your BEC cannot sustain the current your system demands:
Your servo suffers
Your electronics struggle
Your performance drops
Choose your BEC based on continuous output, not peak numbers — and your entire RC system will thank you.