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Old 12-05-2006, 17:36   #16
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Gord, looking at your ohms law stuff, (i shouldn't be the one to ask you this as I have electrical engineering degree) but anyway, is there a way to convert the shunt based ammeter to work with a diffeent shunt.
I screwed up few years back cause I got a 100mA Shunt and a 50mA meter separately from a consignment shop. The ammeter was showing twice the actual amps. Now I noticed that the same shop has another shunt, but my ammeter is not working anymore. This seems like an inexpensive way to get high amperage ampmeters which I am in a desperate need of. All the shunts I have are rated 100amps to 500amps so that should be fine. I know I need to solder in another resistor in the ammeter. I am not sure what how many KOhms

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Old 12-05-2006, 18:02   #17
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In the latest edition of The Boatowners Mechanical and Electrical Manual from Calder I get the impression that while LED technology is the lighting of the future, for general cabin lighting fluorescents are more efficent at present. LED's are more effective where a focused beam is required such as nav lights, reading lights, etc. They also work well for low intensity courtesy lights. He recommends Aspenglow and Resolux as being true marine grade fluorescents that are RFI suppressed. The low end lights like Thin-Lights may not be as they were developed for the RV market.
As for the tinned or untinned debate I will offer this observation. My 25 year old boat was wired with untinned wire and the previous owners also added a bit. Most of the original wire is still in good shape with the exception of the owner added stuff that is all falling apart. This I believe is due to inferior jacket material usually vinyl. While there is no doubt that tinned wire is the best option untinned wire can work in many areas IF one is very careful about using quality wire with the proper waterproof jacket. I believe untinned wire is still the norm on boats built in Europe.

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Old 12-05-2006, 20:12   #18
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LED efficiency

As wonderful as LEDs are they must be viewed in relation to other technologies regarding efficiency. Cold-cathode flourescent technology lamps are the most efficient (not to be confused with flourescent bulbs which are STILL more efficient than LEDs). HID lamps (high-intensity-discharge) are just below cold-cathode technology eficiency yet very expensive and not soon to be ubiquitous.

Behind those are the various incandescent lamps like xenon and halogen which are more efficient than tungston filaments. LED efficiency is barely above halogen incandescent effiiciency and certainly is limited in overall brute output power like halogen lamps.

So, do not assume that LEDs are the ultimate in luminescent output efficiency for your application, as "campy" as they may seem. Red LEds are more efficient than yellow, then green, then blue, then white. White LEDs are very innefficient, and that is what you assume you are getting, aren't you, efficiency?
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Old 12-05-2006, 20:32   #19
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Use your degree background to determine the simple case of two resistors in pararallel. One is the shunt resistance, the othe is the meter resistance. Don't let the other factors confuse you. Obviously you need to determine what is called the "voltage burden" of any shunt when operated at maximum current in order to determine if that value is significant or not in your application. Yet, in general, any voltage burden in consumer marine applications should not exceed 50mV at maximum rated current.

Making such calulations it will become obvious that most shunts capable of measuring practical high load inverter (translate to 1200 Watts input power or more) and windlass motor loads (125-175
A or more) AND having sufficiently low voltage burden will result in a conductance of 10,000 seimens or more. Figure it out for yourself. No normally available D'Arsenval movement will do that. You need digital technology.
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Old 12-05-2006, 20:45   #20
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Now unless you get your kicks, on crawling around in small tight spaces. And love ripping out old wiring. Then go cheap.

If ya want your electrical wiring to last. And to keep running. Then buy the good stuff. Go tinned wiring!!

And when working with that stuff. Seal off all the open wires with shrink wrap. And believe this or not. Use fingernail polish, to paint over the open wiring. I use it on cars for years. A old friend, reffered me to this method. It really works. Don't know how well in a marine environment.

"Those who desire to give up Freedom in order to gain security, will not have, nor do they deserve, either one." - Benjamin Franklin
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Old 13-05-2006, 05:15   #21
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RFI Suppressed Fluorescent Lighting

”... He (Nigel Caulder) recommends Aspenglow and Resolux as being true marine grade fluorescents that are RFI suppressed. The low end lights like Thin-Lights may not be as they were developed for the RV market ...”

Alpenglow make excellent fluorescent fixtures (tho’, unlike most, I’m not all that fond of their aesthetic appearance), but don’t indicate on their website that the ballasts are RFI/EMI Suppressed. Given their general high quality (& price), I suspect they are.

Imtra - IML Resolux fixtures are all RFI suppressed.

Thin-Light offers (or used to) a variety of 12 VDC fluorescent lights, including those with RFI Suppressed Inverter (“P”) Ballasts, such as the 900 series (ie: #949 c/w 13W, 900 Lumen Lamp). I cannot access their website to confirm.

Plastimo offers RFI Suppressed Fluorescent Lights (ie: 8 Watt #17522).

HELLA MARINE Transistorized Tube Lamp (#7372 & 7373) are Interference Suppressed.

Guest doesn’t indicate whether or not their fluorescents are suppressed, suggesting they’re not.
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Old 13-05-2006, 16:27   #22

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Alpenglow made the their rep many (20?) years ago Practical Sailor publicized their fixtures for having no RFI problems. If I was installing new, I wouldn't buy any fluorescent fixtures unless they were guaranteed not to have RFI problems, the cheap stuff inevitably has RFI, or buzzes, or falls apart not too long after being installed. And while white LEDs and high brightness LEDs (the Luxeon stars are incredibly bright and small) have plunged in the last two years...they're still more expensive than fluorescent.
I don't think the selection of crimps and crimping tools can be overemphasized in a marine environment. SPEND the $50 for a ratcheting crimping tool, and brand name crimps, and you'll never regret it. They just don't fail on you. The 500/$10 kit from the auto stores are usually split metal, but the better ones are tubular metal, or have tubular liners, and tinned or copper sleeved. Professional grade crimps, available in a kit from any electrical supply house, are damn close to the price of Ancor fittings.

One year I splurged on a gift for myself, one of the fancy one-handed wire strippers that grips and strips all in one squeeze. These come from many makers in various qualities (avoid the cheapies!) but I'm also delighted with the time this saves. I've heard some folks complain this can nick some of the wire strands, but I've seen very little of that problem, less than any other approach. One shot, and the stripping is done and done to the length I need to match the crimp, in one shot.

When you've made a proper crimp, with the right wire guage to match the fittings, quality fittings, and a ratcheting crimp tool, you can ALWAYS do a gorilla pull on the wires afterwards and they'll stay put. Followed up with a proper seal (and I love those Ancor adhesive-lined crimps!) you'll be able to do the work ONCE and never worry about redoing it. Yeah, that costs more time and money up front. Still cheaper in the long run.
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Old 14-05-2006, 01:07   #23
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There are many things that make wire on boats break.

Get tinned as it resist the salt much better. Copper and salt do not mix.

Support the wire as close to termination as possible. Less movement less breakage.

Proper crimp. I have broken wires with a bad crimp.

Proper waterproof, saltproof coatings over terminals and sripped wires. A wet boat is not a place for bare wires.

Prevent damage to wires. Look in all storage areas for wires. In my boat the motor starter wires was going though a storage area with out any pipe around it and in the bilge. This was connected directly to the battery and not fused.

All of this includes communications equipment as well.

Proper size of wires. A lot of people will oversize the wires in a cruising boat.
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Old 02-12-2006, 11:29   #24
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Do any of the kiwi boaters know where we can get marine grade crimps and male spades and female spade terminals? Does Dick Smith sell them?

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