Flickering lights when thrust applied

Hello there all,
Just a quick question.
I have been experiencing an intermittent issue with the lights on a B-ROV Heavy.
With the lights switched off I am seeing them flicker on and the intensity of light fluttering when I apply any thrust. This is the case for all analog flight control inputs. Vert/yaw/lateral/fwd.
It isn’t happening all the time. But it is particularly bad when I begin the flight. i.e. full battery. Then it appears to settle down.
There is also no indication on the values that the lights are coming on. The value remains at 0%
If they are already on, they can intermittently become brighter.
Is this a dodgy connection somewhere?
Cheers for now.

@HMS It may be a shorted stator on the thruster.

Here is a check you can do to check to see if your thrusters are shorted (you should be able to do this with your thrusters still on the ROV). We did these tests on a known bad thruster:

  1. Take a multimeter and set it to the Ohm setting. You should have a “No Connection” indication when the probes are not touching; “OL” is what we have indicated for ours. This is what you want you want the thruster to read for the following steps.

  1. Remove the shaft collar and touch one probe tip to the little bit of metal stem below the plastic bearing. Touch the other probe to one of the bare wire ends.

  1. You should get a “No Connection” indication if the thruster is good. If it is bad, then you will get an ohm or resistance measure as shown in the picture.

If you find a bad thruster or thrusters send us an e-mail at support@bluerobotics.com and we can begin the RMA process.


Hi there Kevin,
Nice one. Thanks for the suggestion.
All the gear is offshore at the moment. 2 x bluerov heavys. Plus a heap of other gear too. I will be heading out to join it on the 11th and will have a bit of time in hand to poke about and see if it is what you suspect it might be.
Thanks for the advice.

Having a client with the same issue with a brand new system. Will let you know if this is the same issue.


Hi there folks.
This was the issue. I swapped out the offending thruster and all was well.

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It was the issue with my client as well.

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@kklemens @rjehangir

I sold 2 Unit is doing this in about 6 meters of water but not on surface.

Can I do the same test with my insulation tester at 500Vdc? (lowest settings)

Else I will have to unplug all the thrusters and send it for a dip 8x connecting one thruster at a time…

Or do you have another suggestion?


Hi Etienne, I apologize that we never got back to this! I don’t think it’s possible to do this with an insulation tester, unfortunately. The 500 vdc insulation test has the potential to degrade the insulation performance if done for more than a brief moment.

The best way we’ve found to do this is to use a multimeter to measure the resistance between the motor wires and the stainless steel stem at the core of the thruster. I know that can be tedious. Let me know if you have any thoughts.



I have added a second lightchain and are controling it through a separate output on the raspberry pi. It all works great without any thrust. It also works good at 25% gain, but when switched to 50% gain the lighs starts flickering. This is a topside powered system.
The lights flickers no matter what settings they have, even when off.
The original lightchain works as normal without flickering.

Anyone had this kind of problems before?
It seems strange that it should be anything with the thrusters since one chain is ok.

Can this happen if the signal wire crosses a thruster wire in the electronics compartment?