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T200 Power Issues

I am having issues with the T200 thruster. I’m running them to propel a 12ft boat that requires 20lbf. I have a 28V power source which I connected a DC/DC converter to step down the voltage to 16V. From lab tests each thruster seems to be drawing 10A of current (when run in a bucket of water). When doing a sea trial one thruster worked significantly better than the other, I switched out this thruster with a known good one and the same issue persisted. Both thrusters are now not functioning. Is this an issue with my hardware? I’m not sure what happened. Here is a photo of my set up.

thruster-zoom-in

The thrusters were not run in air for more than 30seconds.

Hi @rzaveri,

What is the current ca[ability of you DC converters? The T200s may have been drawing 10 A in a bucket, but this is not an accurate measure of current draw in static conditions, as the water in the bucket moves and circulates immediately. At 16 V, each T200 will draw up to 23 A constant, please refer to the technical details for more information.

Are you running the converters in parallel or separately to each thruster? Is in parallel, they may “fight” each other with slightly different output voltage, this is not recommended.

It looks like your ESCs are setting in some sort of liquid? The picture is a bit hard to make out.

Are all the wires for illustrative purposes only, or what you are actually using? They are too thin to be used with a set of T200s at full power, the voltage drop along their length will significantly hamper power/thrust. Any cable extensions should be at an appropriately low enough gauge to handle 23 A+ each without significant voltage drop.

Can you elaborate on how the thrusters are not functioning? What are you doing, how do they react, and how else have you tested them?

-Adam

Thank you for the quick reply.

  1. The capability of my DC/DC are: input 24V output 19V/10A (190W). My understanding is that the thrusters can function at this power just might not be as efficient?
  2. I am running the thrusters in series but have also run them in parallel. I am providing power to 2 separate DC/DC that are then connected to the ESCs. How does this effect thruster performance? I plan on using two 24V, 512Wh batteries connected separately to DC/DC convectors and so on. I also plan on buying DC/DC converter with an output of 16V/20A - do you know of any reliable ones? Is this a sufficient power plan?
  3. The ESCs are potted for waterproofing purposes.
  4. The wires are for illustrative purposes - I am now using 12AWG.
  5. One thruster was noticeably slower than the other, I replaced it and the problem persisted. After running it for about 30min (in water, attached to the boat) the thruster stopped functioning. I did some tests in the lab on the ESC and DC/DC and it seems that the thruster is the issues and is no longer working.

Thanks for you help!

  • Ruby

No problem, glad to help.

  1. 10 A is not sufficient to run a T200 at full throttle. If you overdraw a DC DC adapter like this, it will overheat and the voltage will drop, leading to all kinds of issues. You could only run them on a setup like this at about half throttle of less to keep draw below the 10 A limit of your voltage converters.
    2.Not sure what you mean here? I was referring to the DC DC converters running in parallel or to an individual ESC/thruster each. Running thrusters in series/parallel does not make any sense? At 16 V, you should be using a DC DC converter that can sustain at least 25-30 A constant per thruster, 20 A is not enough if you want to run at full throttle.
  2. If the potting has a low thermal conductivity, it could cause the ESCs to overheat.
  3. How long are the wire length between each of the components? I encourage you to use a voltage drop calculator to find out if 12 AWG is sufficient for your length.
  4. Please elaborate on “it seems that the thruster is the issues and is no longer working”. How is it not working? Nothing whatsoever, or “jiggling” motion, jerking back and forth without completing a rotation? Have you gone through the troubleshooting steps?

-Adam

Hi Adam,

Thanks for the help - the thruster has started working again! Also do you have any recommendations for running two escs (with thrusters attached) via the same receiver channel. For example when I push one throttle on my transmitter how do I get two thrusters to start moving?

Thank you again!

Hi @rzaveri,

Good to hear you got it working again. If you want both thrusters to be working in tandem with a simple RC receiver, the simplest method is to plug both ESC signal sires into a single channel output. You can make your own adapter, or use a simple servo Y-harness.

-Adam

Hello Adam,

First of all we are truly thankful for your technical support.

We probably have problems which can be related with your explanation here. We are using 48V 30A main power supply (according to competition rules). We convert this main power supply 12V 120A with connected in parallel 4 “48V to 12V 30A DC-DC converters”. Also we supply our Basic ESC’s from a simple PDB directly. But we couldn’t drive our ROV more than 25% gain in QGroundControl(we use 8 motors). When we make it 50%, we lose connection after a while (10-20 seconds) we regain the connection.
Our all electronical connections made according to your schematics. We even use your power and ethernet tethers (which are about 20 meters) for power and connection.
What could be our problem for not using more than 25% gain.
You can find our electronic scheme in the following.

Hi @rzaveri,

Please see my first post in this thread:

Especially with inexpensive DCDC power adapters, it is not recommended to run them in parallel as you have here. Each adapter is slightly different, and beyond just the excessive heating from “fighting” each other, the difference performance will cause current to be drawn from them unevenly. This will result in one being overloaded and dropping voltage to the system rather than them evenly sharing the load.

Disconnect the parallel configuration, and try running one adapter exclusively to two ESCs each, with no other electrical connection between them.

In addition, they may be overheating if improperly cooled. Inexpensive power adapters also tend to be a little generous with their ratings, I would recommend bench testing each individually to confirm performance is as expected and they can sustain the current they say they are rated for.

The best way to know what is going on it to monitor system voltage under load with a multimeter.

-Adam

There are three serious problems:

  1. Most of dcdc are not suitable for combined use. This can try to use dcdc separately.

  2. dcdc can not absorb the back-EMF of the fast switching propeller, which may cause other electronic devices to burn down.

  3. dcdc can not support the instantaneous current of the propeller when it starts, which may lead to unexpected reset.