Wednesday, December 23, 2009

Re: [Electric Boats] Re: Electric Catamaran

 

Hi Matti,


Sorry I missed answering your question until now.

Yes to a degree I am familiar with what's happening with Bryan's Torqeedo's.  The problem is the cooking of components in the the controller and the cause of seems related to long power cables.

On Bryan's cat there is quite a long run from the batteries to the motor on one side.  On the trouble side the cable length is 17m total (that is, the electrical path to the motor and back).

He started with one Torqeedo on one hull and was using this for a short while until he got a second one. (maybe a few weeks?)  And as it turns out, it is the second motor, that has done less work, that had the problem.

Because the only difference between the two motors is the length of cable its fairly clear that this is the cause, although not absolute. In other respects such as load, mounting arrangements and other service requirements they are identical.

I believe Torqeedo are doing tests to try to simulate this problem and if replicable will be able to design the protection needed.

The theory is that the root cause is high induced voltage created when the power is shut down quickly.  Consider when the motor is under full power and the throttle closed quickly to the off position (such as when in a docking manouvre).  When the current is flowing there is a stable magnetic field around the cables over the full length.  When the power is shut off the field collapses, and in collapsing the lines if flux cut the cable and induce a voltage.  Because of the long cable length the voltage spike is high enough to cause a problem.

The Australian distributor, Claude Desjardins, has been really supportive and has supplied replacement parts to get Bryan going again, and has lent him another battery pack to use so that the cable lengths are short.  Bryan is off cruising somewhere now, up around Hervey Bay I think.  In the meantime its up to Torqeedo to continue with testing to prove one way or another if that is indeed the problem.

On my boat I have used the standard cable that comes with the Torqeedo so I have no concerns about this issue.

Cheers

Chris

On 16/12/2009, at 12:40 AM, MattiB wrote:

 

Hi Chris

I just read on another forum that Bryan with School's out has had some problems with his torqeedos and their controllers. Have you heard anything about it, since you are also located in Australia? Do you know if the problem is solved and what caused it? I think he also had e-pods before he converted to torqeedo...

greetings from the dark north

Matti


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