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Thread: Batteries - Current & Lightning - Oh My

  1. #1
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    Batteries - Current & Lightning - Oh My

    Two agm group 27 batteries could fit in the bilge under the sole forward of the companionway, I do believe. It would put that weight lower (actually over the ballast) and more toward the center.
    What are the pros and cons of battery placement? The terminals would be just under the sole. Is this begging for trouble? There's never going to be more than a cup of coffee in the sump.

  2. #2
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    Probably an ok location as long as you are not taking on water for some unplanned reason If the new gel batteries are sealed and you can somehow waterproof all the connections . . .

  3. #3
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    I have gone out of my way to keep the battery and all connections as high as possible. If something goes wrong, the last thing you want is for the electrical to fail (no electrical pump, no radio, no lights, no nothing). My battery is located on the port side on the aft side of the aft cockpit bulkhead, as high as I could get it. The shelves would almost have to be afloat before it the electrical system was done in. Access is through the port lassarette. Although it is aft of the center of gravity where you wer thinking, it does not have the leverage that it would if located in the motor lassarette.

  4. #4
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    ok, Thanks. Imagine somebody has a patent on a simple marketable solution like, say, a 3" plastic cup with a waterproof cable tail that is secured to the battery case terminal areas with a hose clamp. Maybe the battery is vented up the same exit with the cable in a companion tube. I could have retired to florida with an idea like that.
    I like Theis' radical battery arrangement because it IS so protected. It's a good idea to have the starter bat close to the OB, right? Maybe the juice for the conviences can be mounted lower and near panels.
    (I'm putting in a propane locker for a portside stove on the left in back of the cockpit, why not a starter bat locker on the right?)

  5. #5
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    Another thought. On the side of the bulkhead opposite the battery, in the cabin near the shelf, I installed a high amp main cutoff switch. When I leave the boat, and that is switched off, I know the battery is isolated and wont be dead when I return the following week. A word of caution: The cutoff does not cut off the line to the outboard. You may burn out your outboard generator if the electrical is not connected to a battery (the battery acts as a capacitor) when the OB is run. The line from the outboard to the battery must always be connected (at least with the Yamaha, and probably with most other brands as well, I suspect).

    I thought I would be having an electrical starter for the OB and ran #6 wires from the battery to the motor well. Not necessary now that I don't have an electrical starter, but they are in place if I ever need them.

  6. #6
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    battery/capacitor

    A capacitor is some sort of an electrically charged momentary switch? Why is a storage battery acting like that? The charging current goes one way in, then shuts off at capacity, and the charge still continues on a dead loop?
    I.m so dumb on electrics it's a joke. But not to me. It took me through lunch to get the failsafe main switch setup you have. but in no way can I visualiuze it.

    Can you, Mr Theis, be persuaded to professionally ($$) design a basic electric system for 338? A system that could be customized or added on to later? A kind of guidance system for the electrically challanged in 12v dc?
    Last edited by ebb; 05-22-2002 at 03:12 PM.

  7. #7
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    juiceaid

    well hell I just stumbled across a huge resource on the glissando page. When it's time to get wired I'll just plunge in - 381 lighting the way!! A thousand thanks!

  8. #8
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    You're really stretching my memory from engineering school with your question about batteries and capacitors. Batteries are considered huge capacitors, and in power generation and inverters more commonly known as "accumulators". They are used to hold a fixed voltage and prevent voltage spikes. Just like a capacitor, they store a charge, and then release it on demand, or when the voltage changes to negative. When you try to start a motor and connect the positive terminal to the negative terminal (ground), through a starter as resistance, it discharges. When you charge a battery, it stores the positive AC segment above its ambient level (above 12 Volts positive), and then, when below 12 volts positive, diodes prevent the reverse flow of current (discharge back into the generator). The capacitor concept regarding batteries is true not only for big wet cells, but for the little alkaline batteries as well.

    Over the weekend, I will try to draw what I have done to the Atiel electrical system. The reason I redid the electrical system, incidentally, is that I have had two different marine surveyors look at the boat on two separate occasions (going back a few decades) and on both occasions they faulted the electrical system. Since those surveys, the standards for boating electrical systems have been tightened up. If I get it done, I will start a new thread so the design of the electrical system can be discussed as a separate issue.

  9. #9
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    oh...

    I for one am really interested in what you have done to illuminate yer Ariel. I'm still somewhat incapacitorated and impatient to have your dark science graphically revealed.

  10. #10
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    Hey! Why am I sinking?..and where did my thru hull fittings go??

    I'm with you, Ebb. The sailboat electric doesn't make a lot of sense to me either. No ground plate on Noeta and I s'pose if the lightning strikes it'll blow the thru hulls through the hull.

    From all I can gather you gotta have (if desired) 2 separate systems. One purely for electrical generation and consumption and if desired one system for lightning strike protection....(or attraction as some might argue..);p

  11. #11
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    I grappled with that one, and my research has concluded that both lightning ground and boat are connected at a single point, closest to where ground plate. I think, if you check, you will find a wire connected to your water inlet valve in the forward cabin on the starboard side. I believe that was company issue. That wire is the ground connection for lightning. I have never heard of a Alberg boat being hit (although it may have happened), but I am familiar with others - and many others are not water grounded (they are made in California where they don't have lightning). Incidentally, there is a good read on Sailnet this week about this very subject. I'll try to put the URL on this site.

  12. #12
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    BAMMM!

    So why wouldn't a lightening strike blow a thruhull out the bottom of the boat?
    Like it looked like it was all wired together on 338 until I tore it apart. Plates & thruhulls - but somehow they missed grounding the stem fitting and the rudderpost. And the backstay plate.

    Find the Kittiwake 23 site and you'll read of a guy's experience on his Alberg that evidently melted his frigging whole system and carbonized all his toys. Really. It's a great homey site and fun to visit.

  13. #13
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    First off, based on what I have read, there is no such thing as absolute protection against a lightning strike - other than, as I have been taught, if you are within the perimeter of the stays, you personally are protected because the stays form a "Faraday cage".

    You are on point that the wire to the inlet valve is too small, and the inlet valve itself is too small to take a major hit - but it is effective in all but the worst situations. What some people do is to hang battery cables from the stays when entering a lightning storm. What the experts say you need is a copper plate on the bottom bonded to the stays and the electrical system. I have a 6"X18" plate which is about half the size it is supposed to be for fresh water (but sized right for salt water). I am the only person I know that has gone to this extreme. Others, however, have the Guest sintered bronze shoes that are not advertised as being for lightning ground, but appear to be effective. I also carry one of those Forespar metal brushes on my masthead.

    The book about lightning that I considered to be the best I have yet come across to take the "I don't know how it works but maybe ..." out of the witchcraft concept is

    Lightning and Boats, a Manual of Safety and Prevention, by Michael V. Huck, Jr. It is published by Seaworthy Productions, 17125C West Bluemound Rd., Suite 200, Brookfield, Wisconsin, 53008. The ISBN is 0-0639566-0-4

    The sailnet URL that discusses this topic, (with a forthcoming issue specifically about lightning) is http://www.sailnet.com/view.cfm?page=9067

    Do you have the URL for the Kittiwake story?

  14. #14
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    ground plate

    Thanks for all this good thoughtful feedback.
    The grounding plate is, what, a thick piece of copper slapped onto the side of the hull underwater like sacrificial zinc on a fishing boat? No, so it's faired in - and the cable how does it go to the shroud plate? A hole in the side? And something that size disapates the lightening strike without the possibility of blasting your side out? What's better: battery cables, grounding plate, or both? Intense prayer.

    Kittiwake 23 site: www.crosstel.net/~jlfrnkln/
    Scroll down on >History< to Owners Feedback, 1st entry.
    Last edited by ebb; 05-25-2002 at 07:12 AM.

  15. #15
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    Lightning

    The Kittiwake sotry is interesting, and I believe he is correct about the cause of the problem. I have no confidence that he has corrected the problem now however.

    I am assuming his mast is aluminum. The stainless steel bolt he is using will galvonically corrode when connected to aluminum. That WILL happen - and again there will be no electical connection. That is why when you put stainless steel screws into your aluminum mast, alwsys coat the screws with anti-corrosion cream (which is not a conductor) but prevents the threads from corroding and the screws from pulling out.

    Keep in mind that the lightning does not "strike" the mast in the colloguial sense. What happens is that the mast head, if not adequately grounded, builds up a positive charge - and that positive charge can be quite high in electrical potential (that is why people's hair stands on end before they are struck) The way to dissipate and prevent that charge build-up is through the very low resistance path to water ground. If there is even a small resistance path, then the charge will build up, the point of resistance will heat up further increasing the resistance and the boat will attract a lightning strike. If there is a low resistance path, a positive charge can not build up on the masthead.

    This positive charge build up on the mast head attracts the negative charge on the bottom of the cloud. The positive "streamer" actually goes up towards the cloud to meed the negatively charged streamer coming down from the bottom of the cloud. When they meet, BANG!

    The fact that the bolt blew out is indicative that there was a high resistance path at the connection with the mast. Otherwise there would have not been heat generated at that point and the bolt would not have blown out. Once the main path was broken. The lightning went whereever it decided to go and blew out everything.

    In my Ariel originally, all the shrouds had a 12 ga. wire connecting them together (on both sides, but not connecting the port to the starboard side). I have now increased this to a 6 ga. Because the stainless shrouds are individually lousy conductors compared to the aluminum mast, it is worthwhile having them all shrouds connected together so there are six parallel paths (grounding the mast base with an aluminum bolt is evern better. Originally here was then a 12 ga. cable going from one of the starboard shrouds to the water intake. I connected a 6 ga. wire from the port side shroud to the bow pulpit, and a similar 6 ga. from the bow pulpit to the starboard side, so the base of both sets of stays are connected both at the masthead (by a stainless steel bolt and plate - so galvonic corrosion is not an issue at the masthead. From the base of the shroud connection, the #6 cable goes to a 3/4" copper bolt connected to the copper plate. The bolt has to be large - much bigger than the wire size. Current only flows on the outside of a conductor. The wire is multi-stranded so it can be smaller in diameter than the bolt if the wire has multiple strands. The bolt, on the other hand, is like a single strand. And remember, a stainless steel bolt is a lousy conductor. I would suggest you only use copper or bronze (or aluminum in the worst case) for your through hull bolt, and make it as large as is reasonably possible.

    The entire plate/bolt/whatever combination I bought at West last year (about $38 as I recall) and it came with complete instructions. Look in their catalog under lightning or contact West Marine (I don't have a catalog here or I would do it for you).

    Many people just use battery cables laying over the side but connected to a shroud (assuming all shrouds are connected to one another internally as I commented), and I won't fault it in addition to the grounding plate as a good idea just for piece of mind. That is better than having lightning going through a through hull fitting if the main system fails. The problem with the cables, is that the area of surface contact with the water is is not considered sufficiently large.

    The copper plate, or lightning shoe, should not be faired. It is the edges (and the corners) that prinicipally dissipate the electric charge, not the smooth surface. If you fair the plate, you will lose the edges. And NEVER paint the copper plate or your shoe. All metal through hulls should be tied (bonded) to that shoe so that there can not be any voltage buildup between various through hulls (i.e. lightning can not jump from one to another as happened in the Kittiwake).

    Another safety precaution is to annually take a volt meter an make sure there is no resistance between the grounding plate and the mast. If Kittiwake had done that beforehand, my bet is that he would have realized his mast was not grounded.
    Last edited by Theis; 05-28-2002 at 11:01 AM.

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