A factory automation cell running on 24V DC logic has a decision to make when it comes to servos. Either pick standard 7.4V or 12V units and add a step-down converter, or switch to 24V industrial servos and run them straight off the bus. Most engineers default to the converter. It’s the path of least resistance. But that little DC-DC module sitting between the power rail and the servo is creating problems most people don’t notice until after commissioning.
The issue isn’t efficiency. Modern buck converters run at 90-95%. It’s reliability. Every component between your power source and your actuator is a single point of failure with its own MTBF. The converter itself, its input capacitors, its output capacitors, the inductor. One of these fails and every servo downstream loses power, regardless of how well the servos themselves were built.
What Happens Inside the Servo at 24V
Higher voltage does something useful at the motor level that most datasheets gloss over. Torque is proportional to current, but resistive heating is proportional to current squared. Double the voltage and you halve the current for the same power output, which means a quarter of the resistive losses in the windings. The motor runs cooler, the magnets stay further from their Curie temperature, and the insulation lasts longer.
There’s a second benefit on the drive side. At 12V, producing 80 kg-cm of holding torque might pull 6 amps through the H-bridge MOSFETs. At 24V, the same torque needs roughly 3 amps. The FETs dissipate less heat during switching transitions, so the drive board needs smaller heatsinks or no heatsinks at all. In a sealed IP67 housing with no airflow, that matters.
Where 24V Wins
Mobile robots and AGVs are the obvious case. The whole vehicle runs on a 24V or 48V battery. Every actuator that can accept the native bus voltage eliminates one converter. A typical AGV with four steering servos, two lift actuators, and a gripper — that’s seven converters that no longer exist. The BOM shrinks, the wiring harness gets simpler, and there are seven fewer failure points in the field.
Industrial machinery with centralized 24V control cabinets is the other. These systems already have 24V rails running to every station. Switching from 12V servos with local converters to 24V industrial servos is a drop-in upgrade — same wiring, same connectors, fewer boxes to mount and cool.
For a benchtop test rig or a proof-of-concept prototype, stick with 12V. The converter is trivial and you’re not designing for field reliability. But once you’re past prototype and thinking about what happens after 5,000 operating hours in a factory, removing seven DC-DC converters starts to look smart.
Related: CAN Bus Servo: One Wire, No Collisions