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Old 08-26-2014, 11:15 AM   #41
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Thanks Ghost, I'm just going to get off my ass and call all three companies and see what is what. Thank you for all the great responses guys! I always come away from this forum better armed for the great battle of living/loving/crying on our old trawler!
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Old 08-26-2014, 11:22 AM   #42
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God Psneeld, I would love to do that, it just seams the boat keeps emptying the bank account before I can replenish it!! Let alone our down island fund.
Magnum had always been my first choice, but I didn't see that they had load shedding capabilities yet. My concern is if someone pulls my plugs the system will try to power everything from my battery bank.
There's another call for you to make. The Magnum people are very helpful.

The inverter doesn't see the individual loads downstream. Any load shedding device would have to be associated with the panel. You can set the low battery cut out on the inverter wherever you like if you are worried about running down your batteries.
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Old 08-26-2014, 11:28 AM   #43
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Talking

Thanks George, I am calling Magnum first as I have always been leaning towards them. Haven't heard bad things and made in the USA! Now I need to enroll in EE classes at UNO to see if I can build what Ghost did
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Old 08-26-2014, 11:52 AM   #44
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Sorry to be verbose, but the shore power comments make me recall another important idea as all of the electrical works in concert.

In my neck of the woods it's heaters that draw the high loads, not summer ac , but ultimately the same problem. Every year we burn boats down when shore power connections catch fire. This is very common, number one cause. Many more with close calls with melted plugs. I noted long ago when I trade up boat sizes that the 30 amp marinco cords that used to work, suddenly we're problematic. You can run one heater on a 30 amp cord successfully, or even two if they are both intermittently cycling, but once the boat is large enough that two heaters are running at long duty cycles then the shore power connections become problematic. The difficult problem being a majority of 50 foot slips if not brand new have 110/30 power, not 220/50. So you unavoidably have to suck that power through a small straw. Unless those 30 amp connections are perfect,they just don't stand up to anything close to a more continuous 30 amps of delivery without overheating. They just don't.

Many of us went to the smart plugs as they are a much heavier design to try to combat the melting connections. What we found this past winter after a few years of comparing notes among many is that the smart plugs were melting too! The common theme with the smart plugs was it seemed to be with the versions where you put the smart plug on an existing cord. Smart plug beat up a friend a bit more than warranted claiming they were getting installed wrong. Could be, but now that I know empirically that multiple anal retentive types are apparently not able to put these together right, at least one an engineer, another an electrition, maybe it's not possible for the consumer to put these together. Sorry smart plug, I really do love you guys and have stood in your office on multiple occasions as you supported my boat club, but you just walked into this one when you try to blame the consumer. Can't protect you from yourself. You should have investigated who you were talking to before blaming them. In any case, of the pre-molded complete cord and end, we have not seen this problem repeat. So most of us have bought the pre molded cord set now, seems to be working and prices have dropped too.

Sorry, I told you this was going to be verbose.

In summary, when pulling 30 amps more or less continuously on a 30 amp system, even when using upgraded components, it seems we are still on some kind of razors edge. Upgrading the shore power would be the real solution, but that's often not available. Plus, if you cruise north around here, it's not uncommon to run into 20 amp shore power, or a standard household 15 amp which you can't get anywhere close to 15 after the dock dogs pee on them. All of this very common, real life.

So, that's where I got my inspiration that my 48 foot boat somehow needed to be able to get by on much less than 30 amps of power on a typical day. If I can't fix the shore power capacity, and I can't fix the 30 amp connections to be bullet proof, the only thing left is to reduce the load on the cable itself.

That gentleman is why I went with a phase matching inverter. The simple feat is that I can manually select the max current of the shore power inlet. That's a configurable setting. So I set mine on something less than 30 amps, usually 20. In an instant, I never had a shore power connection overheat again. In a raggedy marina with household outlets? I just select 10 amps. I've done it, it works not just in theory, but real life.

The magic why this works is that you only need your shore power to keep up,with your average load, which is much less than your peak loads in most cases. If so, then this system and it is a system, not just one component, it will work wonders. On startup loads, the inverter adds a little more than what you get from the shore power alone. In a while when the peak load drops, the charger goes to work putting back what you just took out. I've arrived at a cold boat and turned on two heaters and the hot water heater at the same time and in 4 hours time the charger had already replaced the enormous load I had taken out when I got there.

The down side? Cost. Batteries. Wiring. These units are not cheap, you need to have a sizable battery bank and often our old wiring finally presents itself as the number one project on the list. All things I would have done eventually anyway, bug they all had to be present together for it to work.

Now that I worry less about my own boat burning down, I just have to worth about all the boats around me.
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Old 08-26-2014, 12:26 PM   #45
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Thanks George, I am calling Magnum first as I have always been leaning towards them. Haven't heard bad things and made in the USA! Now I need to enroll in EE classes at UNO to see if I can build what Ghost did
Actually, if you look on line, the RV guys do this with some frequency. Stuff like this:

Magnum Energy MSH3012M Hybrid Inverter - Tech and How-to - RV Magazine

http://www.rvcruzer.com/docs/PCI_Specs.pdf

However, we have strayed from your root problem! And that is the source low voltage issue. This is something youshould consult with Magnum about while you are at it. .
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Old 08-26-2014, 01:11 PM   #46
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Hello all, throwing out this question hoping for some help with this horrible shore power we have here in New Orleans. Just had my air conditioner compressor die from what I think is the voltage fluctuation at my marina.

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Oh, great. The ancient Cruise Air split system that i've been patching and limping with has finally died too. Oh well, 30 plus years was a good run. Looks like another purchase is in the works.

Maybe that's a blessing. Remember your first post said a compressor went south from what you thought was voltage fluctuation. Maybe it wasn't that at all.

Anyway, I've read that the new Dometic Vector Turbo (etc., for example) units are much more efficient, presumably not only in output but also in electricity consumption. Two of these on your dedicated 30-amp circuit -- especially with soft start protection -- might well fare better than your older units.

Another thought: Probably you don't have to keep the water pump on the same circuit. If it's on that same 30-amp circuit now, perhaps swapping it to your other 30-amp supply side might be an improvement.

Whether you need boost or not...

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Old 08-26-2014, 01:11 PM   #47
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Well add another score George, I'll be calling Magnum tomorrow when I get home again. I've gotta get some sleep to keep the semi between the ditches tonight! Will let you know what they have to say/offer tomorrow. Looks like they can help kill a couple birds. Now if I can only get my company to transfer me to Florida I'll be in some clearer water and more marina options than New Orleans. At least they transferred me from Chicago, so no more snow
Thanks John
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Old 08-26-2014, 01:19 PM   #48
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Damn all you good commenters! I almost got away from this computer. I just ordered 2 16000 webasto and yes the pump is on that 30amp w/AC's. Have a march 1080 gph pump feeding the oldies now, don't know if it'll run 'em with the new length of hose to the v berth where the replacement for the split unit is going. We'll see, maybe 2 inline pumps would do. Ahhh, the money flows threw my fingers so fast.
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Old 08-26-2014, 01:21 PM   #49
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Lots of discussion but no data, has anyone measure anything?
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Old 08-26-2014, 01:26 PM   #50
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Yes, I started another thread earlier to not muddy up the waters but it didn't help! Sorry this thread has crept alittle but I'm still following along nicely
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Old 08-26-2014, 02:13 PM   #51
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As a liveaboard in NJ till December before heading south...I run 3 space heaters at time all on full. 2 on one 30 amp circuit. 2-1500 watt heaters draw about 25 amps if you are getting and maintaining 120 volts to your power cords....so really not an issue if everything is up to standard. They have never been the overload issue like the 2 air conditioners trying to cycle at the same time...they peak over 30 amps...usually not long enough to trip the breakers but the cords run hot.

The other space heater goes on low most of the time because of the water heater and a few other loads. When we have to use electrical appliances in the galley I usually turn that space heater off but the appliances in the galley such as the microwave or toaster oven are adding heat anyway.

My last live board boat was pretty identical to the setup on this one. that's why I'm going 50 amp service because I don't want to pretend I'm camping and usually people would never put up with a 60 amp service to their house...so why would I to my floating house?

The whole way the 50 amp 125/250 plugs secure make me feel much better than the 30 amp with plastic rings that seem to hang by the prongs rather than a more positive connection like the 50.
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Old 08-26-2014, 03:39 PM   #52
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Here's an example of some buck/boost transformers. You can beat those prices easily online.

http://www.wardsmarine.com/catalog-2...ansformers.pdf
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Old 08-26-2014, 06:35 PM   #53
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Before you install your new a/cs I would check your power cords for burnt ends and all connection at the panel and units. If you can shorten the length could help with less resestant and cleaner power. Grainger has a a/c Hard start that will help in a low volt or recycling to quick. Two wire hook up to start cap.
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Old 08-26-2014, 06:56 PM   #54
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Since the issue most likely is the power at your marina, you don't have to mount the transformer on your boat, you could mount it on the dock.
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Old 08-26-2014, 08:00 PM   #55
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Since the issue most likely is the power at your marina, you don't have to mount the transformer on your boat, you could mount it on the dock.
I don't think that's been proven by actual testing and I would certainly recommend testing before purchasing an expensive transformer.

But yes, it can be mounted on the dock if one is necessary. It would have to be weatherproof or in a weatherproof enclosure.
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Old 08-26-2014, 10:15 PM   #56
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The whole way the 50 amp 125/250 plugs secure make me feel much better than the 30 amp with plastic rings that seem to hang by the prongs rather than a more positive connection like the 50.
That's why we run two and don't worry about a thing.

Note: We have a generator and we're not afraid to use it!
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Old 08-27-2014, 06:11 AM   #57
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If burning at the inlet is a worry , simply using the old style 120v 50A inlet on the end of a 30A power hose should do the trick.

Even a 50a 240 plug and socket could be installed on the end of the 30a power hose as its easier to obtain.Only one leg wired.

Remember, the OP has a problem with suspected low voltage and it's best to check all the possibilities before spending big bucks on a "cure" that may not be needed. Then the plug fire would be at the power pole instead of attached to very flamable boat GRP

>Remember, the OP has a problem with suspected low voltage and it's best to check all the possibilities before spending big bucks on a "cure" that may not be needed. <


Many volt meters will record and display the highest or lowest voltage as desired.Fluke for a quality unit.
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Old 08-27-2014, 06:25 AM   #58
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New air-conditioners may tell if voltage is a problem. They will give a low AC code and go offline if you get units with that feature built in.
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Old 08-27-2014, 08:02 AM   #59
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New air-conditioners may tell if voltage is a problem. They will give a low AC code and go offline if you get units with that feature built in.
That's a pretty expensive test.
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Old 08-27-2014, 09:35 AM   #60
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Obviously, and I gave the OP the benefit of the doubt that it needed to go with out saying, that you don't spent money on anything with out doing some testing first.

But crappy voltage from a marina is fairly common. The easiest way to test it is to go to another marina, plug in and check your voltage.
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