Tell me about Inverters

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Frank Arndorfer

After successfully succumbing (again) to our bi-annual case of two-foot-itis, we've ordered a new Hunter 426 Deck Salon to be delivered mid-spring 2003. And we're loading it up like a Christmas Goose with options. One option considered is an inverter. I have a "basic" understanding of it's use (allow us to use limited ac devices while running on battery power) but I'd simply like to know more about their uses, advantages, disadvantages, etc. Also any tips on upgrading the charging system, additional battery capacity, etc. because of heavier potential load. Not planning any real heavy loads. Occasional TV, coffee maker, very occasional hair dryer (hers, not mine. I don't have enough.!!!) etc. Not quite sure I want to make the leap up to a gen set. Thanks in advance for any tips, advice, etc.
 
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Carl and Juliana Dupre

Square and Sine

Hi, Frank. I don't know a lot about inverters, but I do know that there are two general types. One type outputs "true" alternating current; the AC cycles have the true sine-wave cycles. The other type approximates the sine-wave cycles with what are actually square-wave cycles. Supposedly there are some electrical devices that will not work properly with the square-wave cycle; I am not certain what types of devices would have a problem. The square-wave type I believe is simpler, more common and less costly. We have a Heart Interface 10, which is 1000 watts, and it has served us well. In all honesty, I am not certain which type it is, but it was not a real expensive unit, and I expect that it is the simple square-wave type. With this inverter we have powered the microwave, numerous small power tools, a hair dryer, a laptop computer, and a coffee grinder. We have never had any problem with any device that we have powered through the inverter. The inverter also works very nicely "in reverse" and has recharged our batteries on the few occasions each year when are at a slip and have shore power. When you plug in shore power the inverter automatically turns on and goes into "charge mode" and disables the "invert mode" so you can't inadvertently try to feed AC power to the AC panel from the inverter while still plugged in too shore power. I would presume that a loaded 426 (envy, envy) probably consumes enough juice to turn it into a de-facto power boat just to keep the batteries up unless you have a high-output alternator. What alternator does a 426 come standard with? We put in a Balmar 100 amp dual-output alternator and an MC-612 "smart" regulator. Charges very quickly, charges both battery banks simultaneously and independently, and works like a charm. Good luck with the new boat, Frank! We will envy you again tomorrow when we look at a 426 at the Newport Boat Show. Carl and Jule s/v 'Syzygy'
 

Rick D

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Jun 14, 2008
7,201
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Congrads, Frank

Since you'll be one of the early owners, keep us up on the progress and your early impressions. As to inverters, I attach a link that will give you a good overview. Doesn't the 426 have an AC-refrige/freezer to start with? If so, I assume it has an inverter standard. If not, get a good one. I would go for the larger capasity, say 2000-3000 Watts. Your AC load will just increase with time, usage and familiarity with the boat. As to batteries, have two banks of golf cart batteries installed. I put Trojan 125's in which have the highest rating for their size. You can also replace them yourself, although, like several of us on this site, your arms will be measurably longer after you do so. I think the new Yanmars come with 85-amp alternators standard. If so, do yourself a favor and get a three-stage external regulator, or consider the Link 2000 with built-in regulator. If the alternator is a lesser capasity, consider an upgrade to 90 or so amps also. Of course, since you are spending some serious money anyway, how about a small, lightweight genset too? Gosh, its great spending other people's money... Rick D.
 
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Derek Rowell

Just a small (tiny) point, Rick...

...I think you meant 2000-3000 watts, not amps?? If you are planning installing a separate after-market inverter, consider the installation of a transfer relay or switch to control your outlets (many of the more expensive units have the relay built in). I recently installed a Xantrex ProWatt 1750 watt inverter and installed a 30 amp relay, and rewired the ac panel so that only the outlets are switched, that is the water heater and charger cannot be powered by the inverter. One word of caution: I have read in several places that some electronics can be detroyed by the modified-sine (square wave) inverters. In particular SCR based (no transformer) battery chargers have been mentionned - particularly the charger for my 9 volt Makita power tools. I haven't dared to try it! Derek
 
Feb 26, 2004
23,313
Catalina 34 224 Maple Bay, BC, Canada
Inverter Info

Frank In addition to the great Xantrex link provided, suggest you read West Marine Advisors on inverters, chargers, alternators. Use the link, go to Electrical. They explain, in plain English, the information you are looking for. Inverters are built both with and without chargers, so you could have a separate AC shorepower battery charger and a separate inverter, or you could buy one unit that does both, as described in a previous response about the Heart 10 (we have a 15 - 1,500 watts AC inverter, 75 amp charger - they are properly called modified sine wave units). Unless you have some fancy AC electronic equipment on board, a pure sine wave unit is not really worth the extra cost. We've used a TV on board, which is usually the most affected by modified sine wave inverters, and it works just fine, no lines through the screen. The alternator issue is completely different than the inverter charger issue. The alternator is used when out of the slip, away from shorepower. The larger an alternator, the shorter time you will need to run your engine to turn the alternator to "refill" your batteries. You MUST get a three stage regulator to utilize the benefits of any size alternator, because if you don't, the alternator will NEVER put out enough amps to fill your batteries from its own internal regulator (like an automotive unit). Most new alternators that you buy aftermarket (i.e., NOT OEM from the factory on new boats with new engines and alternators) come without internal regulation anyway, so an external smart regulator is required, except for new boats with incredibly stupid alterntor designs that do not reflect the captured wisdom of the last twenty years of battery charging experience. Yup, the manufacturers of boats still don't have a clue about energy on boats, and continue to build alternators on engines on new boats with internal regulation, which each new owner has to "fix." In lieu of decribing this in detail here, try that West Marine suggestion. Also, buy Calder's Boatowner's Manual, which will also explain the answers to all your questions. I bet if you type Calder into this website's search engine, you find thousands of hits. Buy the book...puleeze - for your own sake. If you are going to be using a tremendous amount of 120 volt AC power on board, you either have to plug into shorepower often to charge your batteries, run the engine often to have the alternator charge them, or buy a genset. But why buy a genset (and make yourself into a powerboat) when with careful planning you can MINIMIZE your energy use by using 12 volt appliances rather than 120 volt stuff? The inefficiencies in charging at 120 to 12 volts into your batteries, then converting 12 volts back to 120 volts thru an inverter are tremendously inefficient, power-wise, and usually unnecessary. Also, only you know how you intend to use your boat: two weeks on the hook, or at marinas every night? ONLY YOU can determine that first before you invest your $$ in parts - design the system for what you need, rather than simply buying everything. Finally, regardless of how you'll use your boat, the very best thing you can do is to increase your house battery capacity as much as you can, to at least 400 amp hours, which will allow you to stay away from shorepower for a reasonably long time with minimal recharging requirements (from ANY source). The reason for this is that you'll always have an easier time recharging a bigger bank and the batteries will last much longer if they are discharged at a smaller percentage of their total capacity. Read Calder. We have 365 amp hours in our house bank and have been out for four days and nights without recharging with full power available at all times. Do an energy budget and find out what you intend to use. Then design the system by selecting the components that are right for you. Stu
 
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Frank Arndorfer

Responses

Thanks much for the responses so far. I'm reading with a great amount of interest. Hunter offers a 105amp alternator as an upgrade. The Inverter listed as optional is a Heart Freedom 2000 unit. I assume they rate this as a 2000 watt unit.???? And word from Hunter is a March '03 delivery we will be hull #10 or 12. I guess interest in this boat has been phenomonal. And yes, the boat will have ac/dc fridge and freezer. Air conditioning/reverse cycle heat (needed in Wisconsin.!!) will be ac power only.
 

Rick D

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Jun 14, 2008
7,201
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Duh. Thanks, Derek!

And, thanks, Phil for giving us the edit tool so we don't look like idiots forever. Rick D.
 

Rick D

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Jun 14, 2008
7,201
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Go with the upgrade and option, IMHO

nm, RD
 
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Robert Pugh

Inverters and Batteries

As long as you are looking at the whole system(and it is a system that must work together to accomplish your goal), please remember that your actual battery capacity is 50% of the stated capacity. Thus, a 150 amp hour house battery should not be used to more than 75 amp hours of its capacity. We have a Hunter 380 that frustrated us continually with being under batteried for even a 2-3 day trip. We were continually runnin gthe motor at anchor. We have a Freedom 20 (2000 watt) inverter that came with the boat. We have added two (2) 225 amp hour AGM batteries with a Link 10 monitoring system. The panel that comes with the Freedom 20 is a remote panel only, not a battery monitor--big difference. This equipment fits all of our needs and then some. No battery maintenance! We did find that for some reason, the inverter needed both A/C outlet panel switches to be on before it would operate the outlets. Also, the on/off heating cycle of a coffee pot seems to cause a cycling of the inverter that ends up turning the coffee pot off. Do not know why, and maybe its just my problem. I had a qualified marine electrician go completely through the whole electrical system. He found several problems that occurred during the boat construction stage. None were serious, but you might want someone familiar with inverters to go through your new boat when it arrives. Good Luck!
 
Feb 26, 2004
23,313
Catalina 34 224 Maple Bay, BC, Canada
AC Side of Inverter Distribution

Robert You wrote: "We did find that for some reason, the inverter needed both A/C outlet panel switches to be on before it would operate the outlets." There's a very simple and basic answer to this: The inverter is wired into the AC side of the boat's electrical system, or else it wouldn't work. In order for the inverter, which is putting out 120 volts, to get to the AC wiring in your boat, it is essentially "replacing" the shorepower source. So, either the shorepower OR the inverter, has to be fed TO the main AC 30 amp breaker. Since you need to turn this breaker ON to run your outlets from shorepower, you also need to turn the AC breaker ON to have the inverter power get "into" the AC wiring. What else on your boat is AC (other than the hot water heater) than the outlets? And the water heater has it's own breaker. Hope that helps you understand the situation a bit more. Also, you note: "Also, the on/off heating cycle of a coffee pot seems to cause a cycling of the inverter that ends up turning the coffee pot off. Do not know why, and maybe its just my problem." This sounds like the coffee pot is tripping the inverter, although that doesn't seems likely with your Freedom 20's capapcity and your properly sized battery bank. Is there any relationship to whether or not your batteries are fully charged, or does this happen all the time? Is it a programmable coffee pot? (No kidding, we just bought one that by its timer grinds the beans, makes the coffee and has an adjustable (zero to an hour, I think) time on the heater - maybe that's it.) If it's only the heater under the pot that's causing the "problem," (rather than when it is actually making the coffee) the heater is, of course, a very high resistance AC load that is using up valuable amp hours as long as it's on. Why not consider decanting the hot coffee into a thermos and turn the heater off, thus avoiding the problem altogether and saving those valuable amp hours?
 
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Wayne

Fancy Battery Charger

We had a Freedom 20 installed on the 410 we commission this summer. I would probably do it again but we almost never use the inverter part of the package. I like the fact that the battery charger comes on as soon as you plug in the shore power and flip the main AC breaker. Trying to run the microwave seem to drain the batteries too quickly. Running the microwave with the engine running worked fine. We also had the issue with the coffee pot cycling. The coffee pot and the microwave are our only two AC appliances. Wayne s/v Mahina Kai
 
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