The video uses the reverse demonstration of "fried motor with black pepper" to remind pilots: turning off Low RPM Power Protection, maxing out Startup Power, and setting BLHeli_M's ESC Feedforward acceleration and deceleration to extremes will cause low-speed or stalled motors to withstand huge instantaneous currents. The real parameter adjustment goal is to find a balance between reliable startup, response speed and thermal safety, rather than pursuing the bigger the better for all parameters. Any verification must be done with the propellers disassembled and performed to current ESC, firmware and motor specifications.
The opening is a dangerous counterexample, not a recommended recipe.
The video first deliberately shows a combination that is "most likely to burn the motor": turn off low-speed power protection, set the starting power to 1.5, and push the acceleration and deceleration of ESC Feedforward to 100% in BLHeli_M. The author then made it clear that this was a joke, and if you follow this, you may burn out the motor or ESC very quickly. When reading this content, you must treat it as a demonstration of the failure mechanism, and do not copy the three extreme values into the configurator.
Before adjusting parameters, you should save the current ESC settings and check the ESC model, BLHeli_S/BLHeli_M/BLHeli_32 or other firmware branches, as well as the voltage, propeller and current range allowed by the motor manufacturer. Field names, units, and implementations will change between firmwares, and the interface in the 2021 video should not replace the current documentation.
Why is low speed the easiest to overheat?
When the motor rotates at low speed, fails to start, or is entangled in grass, the back electromotive force is low and the heat dissipation is poor; if the ESC still applies a high drive, the winding will pass a large current, but the heat will not be taken away by the airflow. The idea of Low RPM Power Protection is to limit the power that can be applied when the speed is low to prevent a sudden increase in throttle from directly turning into coil heat.
Turtle mode is specifically mentioned in the video: after the body is overturned, the motor may be stuck in the grass or obstacles. At this time, continuing to push the rocker will quickly heat the motor and ESC. If the motor does not rotate immediately, it should be removed immediately and the obstacle should be cleared after the power is turned off; do not use the accelerator door repeatedly to "hard pull" out of trouble.
Trade-off between Startup Power and Protection Strength
In the implementation explained in the video, the lower the Startup Power, the stronger the power reduction in the low-speed stage; the higher the value, the more aggressive the motor starts, but the current and burnout risk when locked are also higher. If it is too low, it may cause the motor to start slowly or out of step; if it is too high, reliable starting will be replaced by unnecessary thermal burden. The lower limit should be "all motors can start reliably in both cold and hot conditions" and then leave a protection margin.
The release notes add an exception: some large disc motors may not be able to increase speed due to low speed protection and need to turn this feature off. This is not a general recommendation for five-inch machines. This exception should only be evaluated if the motor/ESC combination is verified, using a split propeller or controlled load, capable of monitoring current and temperature, and understanding the consequences of loss of protection.
ESC Feedforward also amplifies transient drive
BLHeli_M's ESC Feedforward will provide additional drive during rapid throttle changes, allowing the motor to follow commands faster. The response may be sharper, but setting the acceleration feedforward too high in the low-speed stage will be contrary to the goal of power protection: the actual applied drive is higher than the base throttle, and the instantaneous current increases accordingly. The reduction end should also not be unconditionally full and should be verified based on motor response, synchronization and heat.
All propellers must be removed for safety testing, and current-limiting power supplies or reliable current/temperature monitoring must be used as much as possible; lithium batteries should be kept away from combustible materials and appropriate fire prevention measures should be prepared. First jog briefly to confirm that all four motors can start in unison, then make a small step from low to medium throttle, and check the motor and ESC temperatures after each round. When there is an odor, smoke, abnormal vibration, howling, or failure to start, power off immediately. Never verify the limit by "trying again".
Operation steps
- Identifying dangerous counterexamples in videos
The opening shutdown protection, Startup Power 1.5 and 100% Feedforward are used to illustrate how to burn out the motor and are not recommended settings.
- Confirm the true effect of the three settings
First understand that low-speed protection limits power, Startup Power changes startup drive, and ESC Feedforward amplifies rapid throttle changes, and then decide whether adjustment is needed.
- Start with minimum requirements for reliable startup
Use conservative values to check the motor cold engine/hot engine start-up one by one under the condition of removing the propeller; higher values do not necessarily mean better performance.
- Verification of stall and turtle mode risks
Do not keep the motor stuck in grass or obstacles powered on; if it cannot rotate immediately, release the control and cut off the power for cleaning.
- Small step test Feedforward and temperature rise
Change only one item at a time, make short low-throttle steps and monitor current, synchronization and temperature; if abnormality occurs, immediately power off and restore known safe configurations.
FAQ
Should Low RPM Power Protection be turned off?
Normally should not be closed just for response. The inability of large disc motors to speed up is a specific exception in the video description and needs to be judged in conjunction with current firmware documentation, controlled testing, and current/temperature monitoring.
The higher the Startup Power, the more reliable the startup is?
Higher may make starting more positive, but it also increases the current and risk of burnout at low speed or stalled. The goal is to find the lowest reasonable drive required to start reliably, not to max it out.
What should I do if the motor is stuck in grass during turtle mode?
Stop driving immediately and cut off the power to clean. Do not continue to push the rod to try to break free. Low-speed stalling lacks heat dissipation and can damage the motor or ESC within seconds.
Can I test these parameters with a paddle?
No. The propeller must be removed for preliminary start-up, synchronization and setting verification, and current limiting, temperature monitoring and lithium battery fire prevention measures must be taken; wearing the propeller will increase the risk of injury and equipment loss of control.
Full timeline transcript
Transcripts are arranged according to video time, making it easy to quickly locate the explanation content. Transcript language: Simplified Chinese.
Hello everyone, welcome to my channel. Today I am not Corin, today I am chef Wang Gang. Today I will teach you a home-cooked dish from FPV, stir-fried black pepper. How can we make a delicious black pepper dish quickly and well? First, we added a little oil to the pot, ah, that's not right. First we open the BLHeli configurator. Here I take the BLHeliS configurator as an example. First, let's turn this off
Low speed power protection, 6rpm power protection is turned off. After turning this thing off, we will not provide any protection to the ESC or motor at low speeds. How much current it has, how much current we can draw. Then in addition, we need to increase the starting power to the highest level, to 1.5. After this thing is turned up, we will also start the motor at maximum power. No matter how much current it requires, it doesn't matter.
If you use the BLHeli M firmware, there is also an ESC front damper. I set this front damper to the highest, and both acceleration and deceleration are adjusted to 100%. With these three options, we will never have to worry about cooking a delicious black pepper dish. Okay, I'm just kidding everyone, please don't do it. If you really do this, the motor will burn out in minutes, either the motor or the ESC.
So why can these three settings protect our motor? Let’s look at them one by one. First of all, what does this low-speed power protection do?
At this time, the very high heat cannot be dissipated, and the motor will naturally burn out. In BLHeli, it provides such a low-revolution power protection. It allows us to not allow the throttle to rise particularly high when the motor rotates relatively slowly. It will reduce the throttle proportionally. It is reduced in proportion to the large amount, which is determined by our starting power.
If the starting power is set smaller, the lower it will be. Originally it was 100% throttle, and then if the starting power was set to 0.25%, it would put it at this time, of course it is not really 0.25% throttle. There is a close relationship in the middle. Anyway, you just need to remember that the smaller the starting power, the stronger the protection.
On the other hand, if you want the motor to start faster, if this is set too low, the motor will start slower and will not be able to reach a certain speed faster. So in theory, it would impact performance today. But for the motor we use for the five-inch machine, the impact is not so obvious. You can try it yourself. But when you adjust this to too high, be sure to note that there is a risk of burning the motor.
Especially when you are in the anti-fouling temperature mode, let the computer plane turn around first, but if it is stuck in the grass, this situation is very, very easy to happen. Then in BLHeli M, it also adds a FeedForward in this electric strip. What about FeedForward, it means that when the throttle changes very quickly, for example from low to high, right? It will drive the motor with a higher throttle than your actual throttle.
Does that sound like the opposite of our low-speed power protection? So if you set the front kneeling too high, it will also lead to using an excessively high throttle to drive the motor at low speeds, causing the current to overshoot and burn your coil. So this is why improper settings of these three parameters will burn the motor. Okay. The above are some of the lessons I have learned after burning countless motors. I hope it will be helpful to you.
If you like this video, I hope you will like it, collect it, repost it, click three times in a row, and send it once. I am Quarank. See you in the next video!
