Will the steering gear burn out if the voltage is too high? Solutions and preventive measures

01Three core hazards of excessive voltage

Hazard 1: Drive circuit burned out

The control board inside the steering gear often integrates H-bridge driver chips such as L298N and MOSFET tubes, and its upper voltage limit is generally between 7.2V and 8.4V. If the power supply voltage exceeds the maximum rating of the chip, such as a continuous input of 9V, the chip will be instantly broken down, resulting in the servo being completely unresponsive or making strange noises. Common symptoms include: the servo does not rotate, the casing is hot, and there is a burnt smell.

Hazard 2: Motor overheating and demagnetization

The coil resistance of a DC motor is fixed. Once the voltage increases, according to Ohm's law (I=U/R), the direct consequence is an increase in current. When the rated voltage exceeds 30%, due to overheating of the current, the temperature of the magnet will exceed 80°C, resulting in permanent demagnetization, and the torque will decrease by more than 50%. In one case, an enthusiast used a 2S lithium battery (with a voltage of 8.4V) to power a 6V servo. As a result, after 5 minutes of continuous operation, the torque was significantly weakened.

Hazard 3: Potentiometer linear distortion

Inside the steering gear, there is a potentiometer for angle feedback, and its resistor voltage division range is designed based on the rated voltage.. If the voltage is too high, the carbon film of the potentiometer will be partially broken down, resulting in inaccurate angle centering, jitter or loss of control. The typical performance is: after the servo reaches the limit in a certain direction, there is no way to return to the original position.

> Keyword integration: rated voltage

Each servo has a clear and exact rated voltage range. For example, the range of common analog servos is 4.8 to 6.0V, the range of standard digital servos is 6.0 to 7.4V, and the range of high-voltage servos is 7.4 to 8.4V. Please be sure to check the servo housing label or instruction manual. If the voltage exceeds the upper limit of the rated voltage by 10%, it will enter the dangerous area.

02Common causes of excessive voltage (based on real cases)

Reason 1: Use a fully charged lithium battery

For a 2S lithium polymer battery with a voltage of 8.4V when fully charged, most standard servos can only withstand between 6.0 and 7.2V. If connected directly, the voltage will exceed the standard. For example, a user directly connected the 2S battery to the 6V servo, and the servo stopped running 10 seconds after turning on the power.

Reason 2: The output voltage of the switching power supply is unstable

There is a situation where the voltage of an adjustable power supply or a voltage stabilizing module of poor quality will rise under light load conditions. For example, the set voltage is 6V, but the output voltage reaches 7.5V when no load is applied. If you use a multimeter to measure the actual output voltage, you can quickly troubleshoot.。

Reason 3: Wrong number of batteries connected in series

I mistakenly used five nickel-metal hydride batteries (six volts) to power a steering gear that requires six volts, but mistakenly used six nickel-metal hydride batteries (seven.2 volts) to power the steering gear. The overvoltage reached 20%. In industrial scenarios, the direct burnout situation is when the 24-volt servo is mistakenly connected to the 36-volt power supply.

03Solutions (sorted by feasibility)

04Preventative measures (to avoid recurrence)

1. Before each operation, use a multimeter to measure the actual output voltage of the power supply. It needs to be tested under no-load conditions, and it also needs to be tested under load conditions.

2. Read the servo specification document and register and record the maximum voltage value and the operating voltage range. For those non-famous brand servos that have not been marked with instructions, a conservative power supply strategy should be adopted, and the voltage should not exceed 5V.

3. If an adjustable regulated power supply is used, the output must be set to the rated value of the servo, and the overvoltage protection, also known as the OVP function, must be enabled.

4. The multi-servo system uses an independent voltage stabilizing module. The purpose is to avoid the voltage drop caused by a short circuit in one servo, which in turn causes the voltage of other servos to surge.。

5. In addition to the assembly operation of the alarm used to monitor voltage, once the voltage exceeds a preset threshold, such as 6.3V, the buzzer will sound an alarm.

05Frequently Asked Questions (Q/A format)

Q1：Servo voltage is too highBut it is not burned immediately, can I continue to use it?

A: No.Even if it has not been burned, but the internal chip has accumulated damage, it will definitely fail the next time it is powered on or under high load, so the voltage should be lowered immediately。

Q2: How to quickly determine whether the servo is damaged due to excessive voltage?

First measure the input voltage. After confirming that it is normal, if the servo becomes unresponsive, becomes hot, or makes abnormal noises, it means that the driver chip has been burned. In this case, the servo needs to be replaced.

Q3: Will the servo torque decrease after the series diode is connected to reduce the voltage?

A, there will be a slight decrease. Every time you reduce 1V, the torque will be reduced by about 10%. However, this situation is much better than burning out due to excessive voltage. Compensation can be achieved by increasing the supply current.

Q4: Do all servos have overvoltage protection function?

A: Not so. It’s just high-end industrial servos, such as the YPMFG series, which have TVS tubes inside, which can absorb overvoltage in a short period of time. However, damage will still occur if the overvoltage continues.

Q5: Is it safe to use 5V to power the 6V servo?

A: It is safe but there is a lack of torque. Under-voltage will not cause damage, but the response speed will become slower and the power will become smaller; over-voltage will directly lead to fatal consequences.

06Action recommendations and core conclusions

The core point is repeated: Excessive voltage in the steering gear is not a "possible burnout" state, but will definitely accelerate its damage. This damage is manifested in that the torque will decrease and the angle will become inaccurate. In severe cases, the drive chip or motor coil will be burned out in an instant. All cases and test data consistently show that if the continuous power supply exceeds the rated voltage by more than 10%, the life of the steering gear will be shortened by more than 80%.

Three-step action plan for immediate implementation：

1. Test and check: Use a multimeter to measure the voltage value at the power supply port of the servo, and then compare it with the nominal rated voltage value on the servo label.

2. Reduce the voltage: If the voltage exceeds the standard range, first give priority to purchasing a DC-DC adjustable step-down module (the cost is about 10 to 30 yuan), and set it to the rated voltage according to the instructions.

3. The protective measure is to connect a zener diode with 5.6V/5W specifications in parallel to the output end of the power supply. This is to implement protection through the reverse breakdown mechanism, or to connect a self-restoring fuse in series.

> Keyword integration: buck module

Finally, let’s focus on: When choosing a suitable buck module, you should pay attention to three points. First, the output current must be greater than 1.2 times the steering gear stall current; second, the output voltage ripple must be less than 50mV; third, it must have short-circuit protection function. The PID-C voltage stabilizing module launched by YPMFG supports inputs from 8 to 30V and can accurately stabilize the voltage to any value from 4.8 to 8.4V. It is the ultimate solution to the overvoltage problem of the steering gear.

Adhering to the above plan, you can do it within 10 minutesServo voltage is too highThe problem is completely resolved and there is no risk in subsequent operations. Remember: It is better to have a lower voltage than a higher voltage. If it is lower, it will have no power, and if it is higher, it will be damaged.