TECHNICAL SUPPORT
Published 2026-02-26
Friends who play withservos, have you ever encountered this situation: after theservos are installed, they either don’t respond, or shake non-stop, or even smoke and burn in severe cases? In fact, many times, this is caused by incorrect selection of the power supply voltage. Theservolooks small, but it is very picky about voltage. If you give it the wrong voltage, it will get angry. Today we will talk about the servo power supply voltage to help you avoid these pitfalls.
This question is the most frequently asked by novices and is also the most critical. Common servos on the market, such as SG90, usually have a nominal operating voltage of 4.8V to 6.0V. But please note that this range is only the range that can "work" and does not represent the "best" range. For example, for some micro servos, if you directly apply 6V to it, it may be a bit overhanging, while for some digital servos or high-torque servos, their rated voltage may be as high as 7.4V or even higher. Therefore, the first step is always to read the data sheet of the servo in your hand, or the small print on the Taobao details page, which will clearly indicate the recommended voltage range. Don't make blind guesses based on experience. If you hit a 9V battery directly, there will most likely be a puff of smoke.
Just seeing the numbers "4.8-6.0V" is not enough, you have to understand the meaning behind them. 4.8V usually refers to the voltage of four nickel-metal hydride batteries connected in series. This is a very conservative operating point. At this voltage, the servo will be less powerful and the speed will be slower. 6.0V usually corresponds to five nickel-metal hydride batteries or four dry batteries (fully charged). At this time, the performance of the servo can be fully exerted, with greater torque and faster response. If your servo is marked to support 7.4V or 8.4V, it is usually a high-voltage servo for model aircraft or car models, and it is suitable to directly connect a 2S lithium battery. Simply put, the higher the voltage, the more "excited" the servo is, but the greater the heat, and the higher the quality requirements for the servo itself.
Steering gear vibration is a particularly troublesome problem, and it is most likely related to the power supply voltage. Think about it, there is a motor inside the steering gear, and the current will surge instantly when starting and stalling. If your power supply is not powerful enough, or the line is too thin, the voltage will be instantly pulled down when the servo is exerted. If this is low, the control chip inside the servo will think that the power is off, causing confusion in logic, and then the servo will vibrate crazily. ️You can use a regulated power supply to do a simple test: slowly adjust the voltage down from 6V and observe when the servo starts to vibrate. That critical point is a signal that there is a problem with your power supply system. The solution is to change to a power supply with higher power and faster response, or directly connect a large capacitor (such as 470uF-) in parallel next to the servo power line. It can act like a small reservoir, replenishing electric energy and stabilizing the voltage during instantaneous large currents.
The servo will not tell you directly about insufficient power supply, but it will hint you through behavior. The mildest symptom is weakness in rotation and the inability to carry a load. For example, if you want to lift the robotic arm, it turns out to be soft. The more serious manifestations are the jitters and abnormal noises just mentioned. The servo will make a sizzling sound and its position will shake back and forth. The most serious situation is loss of control and restart. When you control the servo to turn to a certain angle, it does not respond at all, or your main control board restarts due to this voltage drop. This is because the servo pulls the power supply voltage too low, and even the main control chip cannot bear it. Remember, it is best to separate the servo power supply and the main control power supply, or at least use a voltage stabilizing module with sufficient power.
When choosing a battery for a servo, you mainly look at three numbers: voltage, discharge rate (C number) and capacity. The voltage must match the servo, as mentioned before. The discharge rate is very important, it determines whether the battery can burst out a large current instantly. For example, the locked-rotor current of a servo may reach 2A. If four servos operate at the same time, a current of 8A will be required in an instant. If an ordinary 18650 lithium battery is used, it may only be able to continuously output 2A, and it will not be able to be used in an instant, and the voltage will drop sharply. At this time, you should use the "power battery" commonly used in model aircraft, such as 3.7V 18650 power lithium battery, or high-rate 2S and 3S lithium batteries. Capacity (mAh) determines the battery life. It depends on your needs, but don’t sacrifice the discharge rate for the sake of capacity, otherwise you will be a “foolish person”.
Lines are like water pipes. If they are too thin, water will not flow smoothly. There are usually three servo wires: positive power supply, negative power supply and signal wire. Many people only pay attention to whether the signal cable is connected correctly, but ignore the thickness of the power cable. Especially when you use extension cords or solder your own wires, be sure to use thick enough wire. For ordinary micro servos, a wire of about 26AWG is enough, but if the current is large, it is recommended to use 22AWG or even thicker DuPont wire or silicone wire. In addition, the wiring method is also critical. Try to use "star grounding" or "centralized power supply", that is, directly connect the power lines and ground wires of all servos together, then connect them to a large capacitor, and then connect them to the output end of the power supply. This can minimize the voltage drop and mutual interference on the lines.
Unstable power supply is a syndrome and must be treated from the source. First, check your power adapter or voltage regulator module. Many cheap modules have slow dynamic response, and the voltage drops as soon as the load is applied. Changing to a better switching power supply or using a low-dropout linear regulator will improve it a lot. Secondly, on the circuit board, the power input end of the servo must increase the capacitance. The previously mentioned capacitor is the basis. If space allows, you can even connect a tantalum capacitor or ceramic capacitor of tens of uF in parallel to filter out high-frequency noise. Finally, check that all connectors are in good contact. Sometimes a DuPont wire is loose and the contact resistance increases, causing the voltage to drop entirely on the interface. Naturally, the voltage received by the servo is not enough. Make sure every connection is tight and reliable.
After reading this, I believe you have a new understanding of steering gear power supply. So, before doing a project next time, you might as well ask yourself: Are the voltage and current of the "food" I prepare for the servo suitable for it? Welcome to share the weird power supply problems you have encountered in the comment area, or give this article a like and share it with more friends who play with servos to avoid pitfalls together!
Update Time：2026-02-26
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