TECHNICAL SUPPORT
Published 2026-03-17
Have you ever encountered such a situation? I happily connected the 9gservoto the circuit. However, when the power was turned on, it only shook twice and then stopped working, or the entire microcontroller restarted directly. Don't be too quick to suspect that theservois damaged. There is a high probability that you have not met its "needs" - insufficient current supply. A thorough understanding of the current consumption of microservo9g is the first step to ensure that your small project can run stably.
The normal operation of the steering gear is inseparable from the appropriate current. Many times, seemingly simple connections can cause problems due to current problems. Therefore, understanding the current consumption of micro servo 9g is crucial to ensure the smooth progress of small projects. This can not only avoid problems such as abnormal servo jitter or microcontroller restart, but also allow the entire project to proceed in an orderly manner, laying the foundation for subsequent success.
When an ordinary 9g servo rotates in the no-load state, the current is actually not large, ranging from 50 mA to 200 mA. For example, the no-load current of our most commonly used SG90 is generally just over 100 mA. But this data is for reference only. It is like a person's appetite, whether he works or not makes a big difference.
Once a load is added to the servo and it is used to move something, the current will rise slowly. The current during normal operation may reach 300 to 600 mA. It depends on how much work you let it do, and the efficiency and workmanship of the servo itself. So don't just record the no-load current and treat it as all, otherwise you will definitely fall into a trap later.
Here I want to talk to you about a particularly critical situation called "stuck". Imagine that the servo is turning hard, but it gets stuck on something and cannot move. At this time, the motor is like a cow trying desperately to break free, and the current will instantly surge to a very high value.
For a 9g servo, its locked-rotor current can usually reach 800 mA, or even exceed 1 amp. Such instantaneous current surge is the main cause of system instability. If your power supply output capability is insufficient, the voltage will be pulled down instantly, causing the microcontroller or development board to power down and restart. Many strange problems, such as the servo shaking but not moving, are all caused by the "electric tiger" at this moment.
In the actual use of the 9g servo, we will also find that once the locked-rotor current reaches the above value, the stability of the entire system will be greatly challenged. When the power output capability is insufficient, the voltage drops sharply, and the working status of the microcontroller and development board will be seriously affected, causing a power outage and restart. As for the abnormal phenomenon of the servo shaking but not moving, the root cause is traced back to this momentary strong current shock.
When you use more than one servo in your project, you have to learn to calculate the general ledger. You cannot simply add up the locked-rotor currents of all servos, because it is unlikely that they will be locked-rotor at the same time. But the worst-case scenario must be considered. For example, if you make a small robotic arm, there may be three joints exerting force at the same time.
A relatively safe algorithm is to estimate in advance how many servos will be working under heavy load or locked-rotor conditions at the same time, add the locked-rotor currents of these servos, and then multiply them by a safety factor. The value of this safety factor ranges from about 1.2 to 1.5. Assume that the current of each servo when locked is calculated as 700mA, and there are 4 servos that may output power at the same time, then the sum of their locked currents is 2.8A. On this basis, plus the current of the control board, the power supply must be able to stably output at least 3.5A of current, so that it can be considered reliable.
In practical applications, it is crucial to accurately predict the working status of the steering gear. Through the above algorithm, we can more accurately determine the stable current value that the power supply needs to provide. Only by ensuring that the power supply outputs stable and sufficient current can the normal operation of the entire system be ensured, and problems such as abnormal steering gear operation due to insufficient current be avoided, thereby ensuring that related equipment or systems can perform their functions stably and reliably.
Choosing a power supply is a science, and the core principle is to "leave room". Based on the maximum current calculated just now, find a power supply that can stably output a larger current. For example, if you calculate that you need 2.5A, don't search for a 3A one. You will feel more at ease if you go directly to a 5A one and the voltage fluctuation will be smaller.
In addition, the quality of the power supply is far more important than the nominal value. Many cheap power modules on the Internet are labeled 5V 3A, but the actual voltage drops to 4.5V when loaded to 2A. Give priority to choosing voltage stabilizing modules from well-known brands, or directly use model aircraft lithium batteries and add a reliable voltage-reducing module. Remember, if the power supply to the servo is stable, the entire system will be more than half stable.
Are you confused just by looking at the parameters? Then test it yourself. Set the multimeter to the current setting, change the red test lead to the jack for measuring high current, and then connect it in series to the power line of the servo. Send a rotation command to the servo and you can see the real-time current.
You can measure the current when rotating without load, with load and when the rotor is blocked by hand. Note that the locked-rotor test time should be short, otherwise it is easy to burn the servo. If possible, you can use a USB voltage and ammeter connected to the power cord, or use an oscilloscope to view the current waveform. You can clearly see the sharp current spike at startup, which is very helpful in understanding the problem.
If the measured current is frighteningly large, or the power supply is always pulled down, there are several practical methods. First, weld a large capacitor, such as an electrolytic capacitor from 470 microfarads to 1000 microfarads, between the positive and negative poles of the servo power supply, close to the servo. This large capacitor is like a reservoir, which can provide a buffer and stabilize the voltage during instantaneous current surges.
You can make a fuss about the software. Let the servo rotate less violently, use a program to control it to start slowly, or stagger the start times of multiple servos to prevent them from grabbing power at the same time. If you have tried all the tricks and it still doesn't work, then you have to consider whether the servo is indeed not powerful enough and needs to be replaced with a more powerful model.
When you were working on your own servo project, have you ever encountered a strange experience where the servo went crazy because the power supply was not selected correctly? You might as well share it in the comment area so that everyone can avoid pitfalls together! If you find the article useful, don’t forget to like and forward it so that more friends can see it.
Update Time：2026-03-17
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