Re: [Electric Boats] Glen L Mark Twain 36' pontoon electric motor advice.

On 19/03/13 22:49, boucaneer@ymail.com wrote:
>
> I have heard that if ones electric props gets jammed with weed/rope it can burn out the motor so it might be best if the motors used a belt/cam drive so the belt can slip if the motor/prop jams.

The motor controller should limit the current to below 'destruction of
the motor' if it's properly set up. Some of the cheaper electric
outboards may not have motor current limiting.

On my last outing I ran over a palm-tree frond. Sticks/small logs
usually just get swatted out of the way by the prop, but the fibrous
palm just shredded and wrapped around the prop shaft. I normally run
with my main battery meter in current mode - the current shot up and
bounced off the current limit set in the motor controller - along with a
change in pitch and a sudden loss of speed. Seconds later I hit my
e-stop button to cut the power.

I had to jump into the water and untangle the mess.

My motor controller is rated at about 2.5 times that of my motor, and
has the current limit of my motor programmed into it. In theory it
should be able to sit infinitely in stall. In practice I would bet
something would overheat after a little while if I actually tried that -
but I should have more than enough time to cut the power before
something smokes.

Some motor controllers also have thermal protection of the motor as
well - I was looking at a spec for a controller recently that had a
thermocouple input so that it could consider motor temperature and it
had a programmable back off for motor overheating.








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