Does T200 thruster along with the BESC30-R3 draw any power when no PWM signal is provided?

Hello guys,

I am designing a very power efficient under-water robot.

I will be using BESC30-R3 Electronic Speed Controller to drive the T200 thruster. My question revolves around how much current will it draw in the quiescent state (state in which I don’t want to use the thruster or the Speed Controller) (off state)

I went through the datasheet for the Speed Controller and was not able to figure the accurate current draw for no PWM sent. I have no idea what’s the current draw for the thruster in quiescent state.

Can anyone please help.

Thank you,
Meet Shah

Hi @meetudiii, welcome to the forum :slight_smile:

I just checked a few ESCs and measured the following idle currents (just via my benchtop power supply, so probably not super accurate):

ESC @ 10V @ 14 V @ 20 V @ 24 V
1 6 mA 7 mA 8 mA 8 mA
2 4 mA 6 mA 6 mA 6 mA
3 4 mA 6 mA 6 mA 6 mA
4 4 mA 6 mA 6 mA 6 mA
5 4 mA 6 mA 7 mA 6 mA

Whether or not a thruster was connected did not have an impact, which makes sense because the motor coils should all be switched off when the ESC is idle.

I did also try measuring 6 powered via the barrier blocks we use in our electronics tray, and the current there was a bit higher, at ~66 mA total (~11 mA each).

Hello @EliotBR ,
Thank you for your prompt answer and to check the idle currents.

I also had the same feeling about the motor current draw i.e. it will have no effect.

And if I am correct, by 1,2,3,4,5, you meant the terminals of the ESC right?

I am sorry, I did not quite understand the current draw you mentioned about barrier blocks in electronics tray. Does that mean that the terminal blocks (barrier blocks) use more current? Can you let me know the significance of why you tested it out with the barrier blocks?

Designing a very power efficient thruster system, it is quite a lot of current from my perspective. I have to think about cutting down the main power supply lines (red and black) using a relay, when the thruster is not in use.

Thank you for answering. Please do reply if you answers to my above doubts.

Thank you again,
Meet Shah

No - I was testing idle current draw of 5 different ESCs, to try to get some idea of the variation between them.

From my (admittedly limited) measurements, it seems that multiple ESCs when powered together by the same supply use a bit more current at idle than they would when powered individually. I’m not sure why that would be the case, but I don’t expect it’s caused by a very low resistance connection between them (like the barrier block) - I found similar behaviour when I just powered two and held their power wires together (If I’m remembering correctly I think they were drawing ~9 mA each).

Fair enough, this comment may be worth a read. Note that getting a single relay with sufficient power capacity to handle all your ESCs may be challenging (depending on your operating requirements), so it may be necessary to have an individual relay (or MOSFET) per ESC (perhaps with a shared switch signal).

I see. Will look into this. I think I might use it for connections other than just the ESCs. I have a design in which I will be using 4 relays to power on and off 4 different components, out of which one will be the thruster.

Yes, I will try using a 16A relay to turn on/off the supply to ESC. Let’s see how it goes.

Thank you for your continued help.