Induced voltages from thrusters and ESC

[EThompson]

Hi all new to this stuff. Here is the setup

2 x 20V 30A batteries
2 x AK32 ESC
8 x X T500 Thruster-BlueRobotics

I am seeing positive voltage transients of 15V+ on top of my 20V battery power when I stop or reverse my thrusters when they are driving full forward.

Is this normal? Are there ESC modules that prevent these transients?

Thanks!

 

[bill_delong]

"Cogging" is normal when when slowly accelerating with lower quality ESC's... not familiar with the AK32 but I suspect that may be your issue. I would consider upgrading to a higher quality ESC to resolve this problem.

Good Luck!

 

[EThompson]

"Cogging" is normal when when slowly accelerating with lower quality ESC's... not familiar with the AK32 but I suspect that may be your issue. I would consider upgrading to a higher quality ESC to resolve this problem.

Good Luck!

This is the ESC: https://www.aikon-electronics.com/index.php?id=20 Is this a low quality ESC?

The issue happens when at full forward then sudden hard stop or hard reverse.

Thanks!

 

[biggman100]

Hi all new to this stuff. Here is the setup

2 x 20V 30A batteries
2 x AK32 ESC
8 x X T500 Thruster-BlueRobotics

I am seeing positive voltage transients of 15V+ on top of my 20V battery power when I stop or reverse my thrusters when they are driving full forward.

Is this normal? Are there ESC modules that prevent these transients?

Thanks!

Which Aikon ESC are you using? Is it the 55A or the 35A?

 

[EThompson]

Which Aikon ESC are you using? Is it the 55A or the 35A?

35A

 

[bill_delong]

This is the ESC: https://www.aikon-electronics.com/index.php?id=20 Is this a low quality ESC?

The issue happens when at full forward then sudden hard stop or hard reverse.

Thanks!

Seeing that it's a $24 ESC here makes me think that it may be a lower quality
https://www.getfpv.com/aikon-ak32-35a-blheli32-2-4s-esc.html

Unfortunately I don't have much experience with electronic flight control systems but it sounds like you're using this for some sort of "Air Boat" that requires reverse, not sure if aircraft systems are designed for that type of rigor.

I would consider using a surface based controller to clean up your wave signals similar to what this guy did here using HobbyWing ESC's which are known for higher quality:

 

[biggman100]

35A

That is way too light for the motors you are using, and, according to Blue Robotics, at 20V, each of those motors pulls 34A, so, if you are using 8 motors, and only 2 of those ESC's, you are way over drawing on the ESC. For the setup you have, you would need 8 of the 35A ESC's, one for each motor, and, at 20V, you are at the limit for what each motor draws separately.

Electrical¹
Operating Voltage	7-24 volts
Motor Kv (no load)	202 RPM/V
Full Throttle Current (Power) @ 24 V	43.5 Amps (1044 Watts)
Full Throttle RPM @ 24 V	3100 RPM
Full Throttle Current (Power) @ 20 V	34.0 Amps (681 Watts)
Full Throttle RPM @ 20 V	2740 RPM
Full Throttle Current (Power) @ 16 V	25.1 Amps (402 Watts)
Full Throttle RPM @ 16 V	2350 RPM
Full Throttle Current (Power) @ 12 V	16.9 Amps (202 Watts)
Full Throttle RPM @ 12 V	1900 RPM

 

[EThompson]

This is for a underwater ROV.

 

[biggman100]

This is for a underwater ROV.

Are you doing individual motor control, for submerging and moving around? Are the motors fixed for only up and down movement, or, are they also going to be directional? Do you already have the motors and ESC's?

 

[bill_delong]

This is for a underwater ROV.

In that case I would use that same HobbyWing ESC referenced in the video I linked above, aircraft ESC's are not designed for abrupt start/stop actions like surface based controllers are.

 

[EThompson]

Already have motors and ESC. New to company and this tech. Trying to fix issues. Fixed individual motors and they are directional.

Interesting! Thanks. Looking at replacing them with:

Hobbywing XRotor Micro 60A 6S 4-in-1 BLHeli32 ESC​

or

T-Motor F55A Pro II​

This should give a performance boost, but I do not know if it would affect the original issue that I am trying to explore.
I do have a way to mitigate the problem. Just wondering it this is something that is common and if better ESC's have built in circuitry to handle this issue.
I have very limited space so the 4 in 1 works better.

 

[bill_delong]

I would try to hit a forum with people who have boat experience, they can confirm what you're looking for:
https://www.rcuniverse.com/forum/rc-boats-229/

 

[biggman100]

Already have motors and ESC. New to company and this tech. Trying to fix issues. Fixed individual motors and they are directional.

Interesting! Thanks. Looking at replacing them with:

Hobbywing XRotor Micro 60A 6S 4-in-1 BLHeli32 ESC​

or

T-Motor F55A Pro II​

This should give a performance boost, but I do not know if it would affect the original issue that I am trying to explore.
I do have a way to mitigate the problem. Just wondering it this is something that is common and if better ESC's have built in circuitry to handle this issue.
I have very limited space so the 4 in 1 works better.

You can try the XRotor ESC, but, i think you will still run into cogging issues. At bare minimum, with 8 motors, you need 300A to run them properly, and that is when the motors are running with a light load. Burst amperage could be as high as 550A on start-up. This is the ESC Blue Robotics recommends for each of those motors: https://bluerobotics.com/store/thrusters/speed-controllers/besc500/ What are you using to control thrust, motor speed, and direction?

EDIT: Years ago, for a school project, i did something similar, but, mine was a surface vessel with 4 side thrusters, but, i cheated, i just bought the motors and ESC's as a unit, kind of like these: https://www.amazon.com/Underwater-b...cphy=1023015&hvtargid=pla-1430999298422&psc=1 It was a nightmare though figuring out how to get them all to work together, at least, for me.