When I first saw this post I wondered if the pitting seen on the motor was because the DC & AC system were bonded to the motor?
If you have the wiring diagram for your boat, chances are the ac green is grounded to the ICE. On my Sabre the ICE was also bonded to
the keel along with the thru hulls & lightening protection.
Tom Hurby on the Electric Seas site had a decent post on this subject saying the DC system on an EP boat should be free floating, connected to nothing but the negative terminal on the battery. It's also my understanding the prop shaft should be isolated from the motor so there is no connection between the shaft & the DC system trom the electric drive itself seeing how it's mounted on metal. The anode on the prop shaft only protects the shaft & prop because of dissimilar metal issues.
IF you have the AC ground connected to the DC buss & it's bonded to the electric drive this may be the problem.
I'm struggling with this right now because I'm rewiring the whole DC/AC system on my boat, have a 10kw drive I'm installing & uncertain if I should terminate the AC green to the thru hull, lightening bonding system. My DC will be free floating & the prop shaft will be isolated from the drive. I do not plan to keep the boat in a slip connected to marina shore power so I'm not sure if a galvanic isolator is necessary.
What do you think?
Bob
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On Sun, 4/2/17, king_of_neworleans <no_reply@yahoogroups.com> wrote:
Subject: Re: [Electric Boats] Re: Protecting the motor
To: electricboats@yahoogroups.com
Date: Sunday, April 2, 2017, 6:46 AM
Maybe improving the
bonding between motor casing and ground, and upgrading your
zincs would help more. You need the ones made for aluminum
boats, which are not actually zinc, but magnesium I think.
Hopefully someone will correct me if I am wrong, but I think
being proactive against electrolysis will help more than
anything.
Posted by: bob jennings <sabre281@yahoo.com>
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