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post #121 of 283 Old 01-14-2019
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Re: Electric Conversion log for Kahleesea

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Lightning.

Your relays may fuse closed.

Food for thought anyways!
Sean
Excellent point!

There is inherently increasing danger proportional to the amount of energy storage capacity, the rate of charging capacity, the max discharge rate, and the size of the loads one has aboard their boat.

A 1 A max @ 1.5 Vdc battery is pretty forgiving.

A 1 A max @ 12 Vdc wall wart is still fairly forgiving.

A 10,000 A max @ 48Vdc LFP battery bank, not-so-much.

The safety measures one needs to employ increase proportionally with storage capacity, charge capacity, and loads.

The energy available in a large LFP storage bank can certainly exceed the
max interrupt capacity of your relays, and even more importantly your over-current protection.

Lighting certainly can.

Lightning does whatever the heck it want's to.

The drawback of supporting an extremely high discharge current, is that an extremely high discharge current can be supported, but not always necessarily as intended.

It would be a real downer if one's vessel survived the lightning strike, but not the ensuing electrical fire.

Just like sailing takes a day to learn and a lifetime to master, so does safe electrical system design and installation.

What you don't know CAN hurt you.

Despite all of the benefits marine electrical systems bring to one's boating enjoyment, they can and do unleash one heckuva fury if not respected.

The larger the system the more serious the risk.

This is not fear mongering, this is pure FACT, and a lot of folks either ignore it or are completely oblivious to it.

I believe that a DIY 5 HP electric motor, charging system, and associated battery bank is far, far, far, more dangerous than a commercially available 20 HP auxiliary diesel.

Frankly, knowing what I know, I wouldn't purchase a boat that had one, regardless of the owners self-proclaimed ability.

Just because it hain't burnt to the waterline yet, doesn't mean it won't, there's always tomorrow.

Again, I am very glad to hear that you are having someone qualified look over your plans, material lists, and installation, for your sake, the people you invite on board, and the others you park near.

Not sure what your insurance company will have to say about your electric propulsion system (should likely check that) but if you have it inspected by a pro, at least you have that in your corner should you have a liability claim because of it.

Last edited by boatsurgeon; 01-14-2019 at 03:08 PM.
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post #122 of 283 Old 01-14-2019
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Re: Electric Conversion log for Kahleesea

Interesting read. My wife and I are thinking about building our next boat. Been considering a solar electric set up.

With all this talk of ABYC standards, I am wondering if the OP could simply buy a set of the standards. Maybe buy the course material for the ABYC course? The course looks to be expensive, but only 4 days. So I don't think there can be an overwhelming amount of material?

IMPORTANT ABYC ELECTRICAL CERTIFICATION COURSE
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Re: Electric Conversion log for Kahleesea

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Interesting read. My wife and I are thinking about building our next boat. Been considering a solar electric set up.

With all this talk of ABYC standards, I am wondering if the OP could simply buy a set of the standards. Maybe buy the course material for the ABYC course? The course looks to be expensive, but only 4 days. So I don't think there can be an overwhelming amount of material?

IMPORTANT ABYC ELECTRICAL CERTIFICATION COURSE
To be eligible to register for an ABYC certification training event, one must be employed in the marine industry and have at least 2 years of documented, related experience, attested to by the employer.

ie. Experience servicing gas or diesel marine engines does not count toward experience for an electrical certification eligibility.

But as I posted previously, one can become a member for a very reasonable fee and can then download any standard in the library.

Just beware that reading standards and watching videos is only a small part of becoming a skilled DIYer.

It takes a lot of mentoring and practice.

I recommend baby steps, starting out with small projects and having all work inspected by a "certified" pro, before tackling big projects.

Just like building the dinghy before the ship to pull it.

Why?

One can't know, what they don't know, until they learn so.
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Re: Electric Conversion log for Kahleesea

Looks like any body can buy the standards. It doesnt look like you need to be certified or a member to purchase the standards.

$75 I think.

https://abycinc.org/store/ListProduc...x?catid=189651
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Re: Electric Conversion log for Kahleesea

Here is the certification guide/study guide for the technicians course as well. Looks like $100. So $175 for the study guide and the standards.

https://abycinc.org/store/ListProduc...x?catid=492999
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Re: Electric Conversion log for Kahleesea

Captain Canuck, I just want to reiterate that I am on your side -- I am also doing an electric conversion and I am just urging a holistic approach to engineering the boat as a system, and understanding the effects of uncontrollable, unexpected events on that system. And, I keep posting, um, lets say "strong suggestion" posts because I'm not just trying to help you, I'm trying to help everyone reading this thread too. Ultimately, what you do with your vessel is your business, I just want you to be successful. With that said...

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Lightning - the motor will be about 8' back from the mast, and the controller and motor both have fuses on them, so an overload making to batteries, and then to the BMS, seems unlikely. I'll look into it, though.
My FCC issued call sign is WK7R, I am an extra class ham radio operator. Out in Arizona (as in many other places...) we do things like put repeaters/antennas next to commercial equipment that is mounted to 100'+ towers on the top of 7000' mountain peaks that get struck by lightning quite often -- as in multiple times every time a storm blows by. A large part of the body of knowledge in our hobby at this level has to do with effectively managing the 30,000+ amps of RF energy (Lightning current amplitude rises and falls so fast, the energy is effectively at radio frequencies and behaves as such, so we refer to lightning as RF energy) and protecting sensitive equipment (and dwellings, and people) from damage in this environment.

I guess I'm saying in no uncertain terms that I am better equipped to make a guess about what happens when lightning strikes your boat than you are, no offense intended. Please do look into the subject. It's actually one of the fascinating ones, that's a lot of fun to learn about. Things like how electricity at RF only conducts on the surface of conductors (That's why Faraday cages work). The sea is a conductor too, and when your boat is struck by lightning, often it travels down the outside of your mast, until the high impedance, low surface area ground cable turns a little too sharply toward a thru hull and the lightning finds a shorter, lower impedance path to the surface of the sea by blowing a hole through the side of your hull causing a pinprick leak at the water line, that may wind up sinking your boat.

The fact that lightning at 30 million volts that just arced through say 3000 feet of free air are going to LAUGH at the 1/4" arc gap in your fuse as it turns into a conductive cloud of plasma.

The fact that lightning is at such immense current that it creates an incredible magnetic field as it flows through conductors (including the air..) and actually induces (as in magnetic induction) current in nearby parallel conductors (including signposts, masts, shrouds and humans who happen to be standing near by,) turning them into the secondary winding in a transformer such that even though the conductor may not be directly involved in the strike path, damaging currents flow (including enough to kill people, erase RAM, corrupt flash memory, fry transistors and FETs that fail shorted...)

Look into boat lightning strikes/near strikes. It's really scary the crazy things that can happen. And while even if we know how to manage lightning energy on towers and radio shacks on the tops of mountains, the same techniques are almost impossible to effectively employ on a fiberglass hulled boat like yours and mine. The insulation of the glass really works against us in the attempt to make the whole boat, as an electrical entity, rise and fall together with the voltage potential of the surface of the sea. It's just not realistic to effectively do that. Steel and aluminum boats are in a much better position in that regard. I guess the point is You Should Expect Every Electrical Device On Your Boat To Fail In The Worst Possible Way It Can.

While we will still build cool boats out of glass, or retrofit them with all manner of propulsion and sail them in spite of the forces of nature, we might as well make them somewhat failsafe so that even if everything shorts, every electronic device subject to the invisible electrical, magnetic, and electromagnetic forces of nature is destroyed... the consequences will still be manageable if, heaven forbid, we are on that boat when the worst happens.

And a for the record.. https://www.boatus.com/magazine/2017...ng-strikes.asp the national average is 1 in 1000 sailboats are struck per year. And 3.3 per 1000 in Florida..

That's the stuff that keeps me awake at night... until it's actually storming. Then there's really nothing left to do after making fast to your mooring than to raise your drink, toast to life, and pray to God that you've done enough to prepare.

Personally, I don't want to be weighed in the balance and found wanting.


Sean

P.S. Dude I am totally sorry for all the big long preachy posts, I don't mean to be so damn serious. There's just a lot of really interesting things out there that I've spent a long time trying to learn..figure I'd try to save you the trouble of a lot of the research.
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post #127 of 283 Old 01-15-2019
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Re: Electric Conversion log for Kahleesea

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P.S. Dude I am totally sorry for all the big long preachy posts, I don't mean to be so damn serious. There's just a lot of really interesting things out there that I've spent a long time trying to learn..figure I'd try to save you the trouble of a lot of the research.
Preaching to the converted (or is that inverted ;-) brother.

Nice Post.

Spot On.

Now I can't sleep.

About 20 years ago, I saw lightning strike a sailboat on the hard in a marina in Middle River (Chespeake) that flashed over to the marina office electrical service panel, which took out the office electrics and comms.

I studied lightning and marine lightning protection systems (not likely to the to the extent you have), some time ago, following Dr. Ewen M. Thomson's work, but had set it aside.

Our boat is equipped with a factory lightning protection system, which is hardly adequate, but at least it's something.

Now it's top of mind again. (Thanks. ;-)

(We head south to Florida in 3 years.)
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Re: Electric Conversion log for Kahleesea

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Looks like any body can buy the standards. It doesnt look like you need to be certified or a member to purchase the standards.

$75 I think.

https://abycinc.org/store/ListProduc...x?catid=189651
I considered that. Honestly, it's faster and more efficient to hire a human being who knows them. A set of codes can't answer questions, and since I'm doing something a bit novel it's better to talk to someone who's been there, done that.

Even at $110/h it's totally worth it to me to have a real live person to talk to. Assuming they know what they're talking about, which I'll be able to determine in short order. There are few things more frustrating than hiring an expert who knows less about a subject than you do. It's happened to me a few times. I once had a very experienced Honda mechanic (30 years+, and trained in Japan to boot) tell me there's no way my diagnosis of my Civic was correct, even after I explained to him all the steps I took. An hour after the car got to his shop he called me to apologize. He's never seen a starter fail at under 150k, and the vast majority outlast the car. The car had 65K on it at the time.

My point is, even the most brilliant expert can be wrong. Sometimes experience works against us, and we encounter something so far outside of the norm that we can't believe it's true. This is why solid, objective diagnostic skills are so very important in any job where you fix things.
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Re: Electric Conversion log for Kahleesea

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P.S. Dude I am totally sorry for all the big long preachy posts, I don't mean to be so damn serious. There's just a lot of really interesting things out there that I've spent a long time trying to learn..figure I'd try to save you the trouble of a lot of the research.
For the record, the only long preachy posts I don't like are the ones that I don't learn anything from. If you've got knowledge, bring it.

FYI, every time I hear something "can't be done" my brain says "That just means someone hasn't engineered a sufficiently robust solution yet." Yeah, that gets me into trouble sometimes. Other times, it leads to awesomeness.

Re: Lightning:

I think I'll review how well connected my mast is to my wing keel. I seem to recall it has a relatively thin cable connecting them. Maybe a 2 or 4 gauge? Maybe I should invest in a 0000 cable as a starting point. I definitely want the path of least resistance to NOT be through the hull.

I think I've already mentioned that all three sensors have to be positive in order for the charging circuit to close. I'll have to look into some way of safeguarding that. I'm not against using a ridiculously large relay to protect the batteries if necessary. It's not something I've really considered, so I'll have to dig into it.

At least I won't have to worry if I'm at sea and lightning strikes the batteries directly...
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Re: Electric Conversion log for Kahleesea

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FYI, every time I hear something "can't be done" my brain says "That just means someone hasn't engineered a sufficiently robust solution yet." Yeah, that gets me into trouble sometimes. Other times, it leads to awesomeness.
I've actually tried to figure out how to use LiIon (to be clear: not LiFePO4) packs safely in a boat. The best plan I could come up with was to mount them in a ventable box (that vents aft) and mount that box to the aft rail with QDs so in the event of a thermal event, they could be jettisoned. But then I considered the ratio of time I would actually be in the boat and able to jettison said batteries manually vs. the time i am NOT in the boat, then failsafe automated solutions to do that.. Maybe nylon straps that went through small slits to anchor inside the bat box so if that it got hot in there, they melted, and the box fell into the sea. But then I remembered what lithium does in water.


....hrm okay, so the box of flaming death is now floating around a) my boat b) the wooden marina full of plastic boats, like McNamara firebombing WWII Japan... It's about then stopped trying to engineer a safe solution for an unsafe chemistry.

Quote:
Re: Lightning:

I think I'll review how well connected my mast is to my wing keel. I seem to recall it has a relatively thin cable connecting them. Maybe a 2 or 4 gauge? Maybe I should invest in a 0000 cable as a starting point. I definitely want the path of least resistance to NOT be through the hull.
RF only travels on the surface of a conductor. 0000 cable has a radius of .23", so a circumference of 1.45". That's not a lot of surface area and represents a high impedance to RF relative to the say, 4" surface area of 2" wide strap, or far better the 12" surface area of 6" wide copper strap. When grounding for lightning...use strap. Far superior RF conduction for the amount of copper. https://www.gacopper.com/ is a great source used by amateurs and professionals. Lot of good information on grounding linked from that site too.


Quote:
I think I've already mentioned that all three sensors have to be positive in order for the charging circuit to close. I'll have to look into some way of safeguarding that. I'm not against using a ridiculously large relay to protect the batteries if necessary. It's not something I've really considered, so I'll have to dig into it.
The vacuum filled high amp contactors are pretty good, the dielectric breakdown voltage is much higher for a given gap -- however, small metal vaporizing contact surfaces will become plasma in a strike, so that can negate that during a direct strike event, and the resulting slag may perm bridge the gap, so be cognizant of that.

Quote:
At least I won't have to worry if I'm at sea and lightning strikes the batteries directly...
LUCKILY...that's not likely to actually happen, and if it does happen all bets are off. It's the induced currents in your electronics/protection systems in strikes/near strikes that you need to concern yourself with.

Carry on,
Sean

Last edited by texlan; 01-15-2019 at 08:52 AM.
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