[PSUBS-MAILIST] Thruster Test

[Alan via Personal_Submersibles]

Thanks Hank,
I should mention that another thing I was looking at was the depth that
I was running the motor. I had read that the top of the propellor blade
should be at least 12" below the surface & this seemed to be about right.
I will lift it up a bit & see how it goes next time. 
I am wanting to mount the horizontal thrusters as high as possible to keep
them as far away from the sea bed as possible when I'm on the bottom.
Getting them at the right height may take some in depth calculations of
weight & buoyancy.
Alan

> On 11/01/2019, at 10:57 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan, well done!
> Hank
> 
> On Thursday, January 10, 2019, 2:52:43 PM MST, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hi all,
> Bolted my brushless thruster on a Minn kotta outboard bracket & took
> it for a run on the back of my inflatable yesterday.
> Photo shows 48V battery pack in battery box, with an oil compensator, speed
> controller in plastic box & red servo tester ( speed input ) on top of it.
> The servo tester is wired to the speed controller & turns the pot input into a 2.4ghz signal. I knew this would be the weak link as it was a cheap unit that I had
> previously had trouble with. Possibly the loose pin connection in to it.
> I had trouble from the start & swapped to my backup which was a radio control
> transmitter & receiver. 
> I was running the brushless motor on sensorless mode. This means the commutation
> is sequenced based on position feedback from the motors back emf.
> This wasn't working well on high speeds & was jumpy or stopping completely
> as it lost it's sequence. All my motors (11) have hall sensors for sensored control
> but I had problems setting that up in the computer program so ran without it
> as I wanted to get on the water. The speed controller operates on both so the
> "not so good" sensorless control is a back up if a sensor fails.
> Speed controller temperature got up to 75C, it has an over temperature function
> that backs off the power at 80C, so I stopped to let it cool. I did have heat sinks
> glued to the top of my battery box to mount the controller on, but when I set up
> at the beach I found I couldn't reach that position as the wires weren't long 
> enough :( . Highly recommend that any motor controllers have good heat sinks
> or are heat sinked to the hull as it will increase their life or save them from failing.
> Was followed by a small stingray for a while so am thinking the motor may put out
> an attractive vibration to them!
> The thrust was good & I am intending to have 4 horizontal thrusters, so should
> speed along.
> A few things to work on before my next outing.
> Alan
> 
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