The current and power of T500 draw too low （15A @24V)

Blue Robotics Products Thrusters and Motors
1

I used 4*T500 thruster and pixhawk 4 for unmanned boat project. But i only measured about total 55A in full throttle current by using 24V lithium polymer battery(15C) . This mean each T500 only draw less than 15A (360W). How should i get more power? This is less than the current which official announced 24V Full Throttle Current (Power) can reach 43.6A.

For differential thruster on boat， i setup 2 thruster as ThrottleLeft and the other 2 as ThrottleRight (function 73 and 74) in Pixhawk. Any suggestion would be greatly appeciated.

2

Hi @howard, welcome to the forum :slight_smile:

A few questions to clarify:

  1. Is the 15C rating of your battery for burst current or continuous draw?
  2. How are you measuring the current usage?
  3. Do you have voltage measurements from the battery?
    • This could help to make sure it was charged to start with, and that it was able to maintain its voltage under the draw from the thrusters
  4. Are you using our Basic ESC 500, or some other speed controller?
  5. Do you have any cooling for the battery and ESCs, or are they just sitting in still air inside an enclosed plastic boat hull?
    • It’s possible the battery or ESCs are overheating, and reducing the maximum power output as a result
  6. Can you try running a test with only one or two thrusters configured as motor outputs, and seeing whether that has a higher current draw per running thruster?
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Dear @EliotBR

Thanks a lot for the help.

  1. The 15C rating is the burst current of the battery. But, i also used the max continuous drawing current 150A of another battery while i got the similar result.

  2. I measured the current by Fluke clamp meter and coulombmeter which was connected to the battery.

  3. I also got the voltage value and the battery can maintain stable voltage in 80-90% battery level.

  4. I used your T500 basic ESC.

  5. I tied ESC on the aluminum plate but they were in inside an enclosed plastic boat hull. However, i also open the hull to conduct very short test. One of ESC is abnormally overheating than another 3 ESC.

  6. I have tested motor one by one. But per running thruster is about 14-16A in full throttle. They can not get higher current.

4

@howard Can you share a picture of your setup? Sometimes that helps to identify issues. A few things come to mind:

  1. Is the wiring sufficient for this current? If not, the voltage drop through the wiring could significantly reduce the max thruster power. You should have short lengths of wire where possible and use at least 12AWG wire for power to each ESC.
  2. Can you verify that the Pixhawk is output full throttle signals like 1900 µs or 1100 µs (depending on rotation direction)?

-Rusty

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