Inverter

[hfmckevitt]

I am looking to install an inverter to run the refrigerator while under way. I have a generator on board, but do not like it running while motoring.
The boat is a 45' Aquarius with twin Cat 3208T.

Any ideas as to size?

Thanks
Henry

 

[FlyWright]

What size fridge? Do you know the startup current draw? They take more to start up than to run once started.

I run an older dorm size fridge on a small 1000W inverter. I can also power my small microwave simultaneously.

If you add an inverter, inevitably you'll find more uses for it. Microwave, heater, fans, lights, chargers...Don't undersize the inverter, the fuse or the cabling.

 

[kulas44]

Defintely get an inverter/charger combo. I like the Magnum Energy units, excellent support.

 

[Moonfish]

Ditto on Magnum.

 

[O C Diver]

Magnum Energy!

If you're going to use it for other items, decide if you need a true sine wave or a modified square wave will work. Considering changing mine as some of my appliances don't like the modified square wave.

Ted

 

[hfmckevitt]

Thanks everyone, but what size would you go for on an inverter charger?

 

[JDCAVE]

Thanks everyone, but what size would you go for on an inverter charger?

I think it depends on the draw on your fridge. A 2800 watt Magnum inverter charger theoretically will run 23 amps at 120 volts, but more realistically the efficiency will be lower, 15-18 amps.

I would suggest, you don't just want a small inverter. 2000 watts would be a minimum in my opinion. You will need at least that if you want to run a coffee maker or microwave on inverter power. A fridge will draw 5-8 amps at 120 volts. The Magnum 2812 is an excellent unit, allowing you to charge at 125 amps on shore power. The other part of the system, when using an inverter while travelling is the size of your alternator. You will also have to recharge your house bank while travelling. Size matters.


Jim
Sent from my iPad using Trawler Forum

 

[Bay Pelican]

Also have good things to say about the Magnum units. Have the 2812 and its charger output when running the generator is substantial which reduces generator run time.

The 2000 watt unit would not start my Splendide washer/dryer but that may not be a consideration for you.

 

[FF]

Many truck units of about 1000W - 2000Ware about 1/5 the cost of a "marine" unit and work as well.

A 1500W unit is about $100 at Amazon.

These are mostly square wave units that power most fridges and kitchen goodies fine.

Sine wave is required for very heavy loads , air cond , scuba refill, water maker , but hardly a house fridge.

Charging is best left to a modern smart charger as its simpler to replace one item after failure , or your needs change.

 

[twistedtree]

An inverter/charger is one area where I think it's worth the larger up-front investment to get a quality unit with good capacity, that includes a charger. Once you start using it for one appliance, you will quickly succumb to the convenience and utility of having household-style power available. You will want to make coffee, and your wife will want to use a hair dryer. You will charge your phone and iPad and laptop, and you will be able to use power tools on board. It's all just a matter of time.

So I would follow the advise of others and get something in the 2500-3500W range, get a sine wave inverter/charger, install it correctly, and enjoy it for years to come. If you buy something small, it's only a matter of time before you will be wanting to upgrade it. And if you get a modified sine wave inverter, it will be harder on your appliances, consume more power due to inefficiencies, and possibly damage appliances.

My first and last modified sine wave inverter was almost 20 years ago, and I woke up one morning to a smoldering and spitting Dewalt battery charger that I had left on over night. It was smoking and oozing chemicals, all because of the square wave power. Needless to say, that was the last square wave inverter I bought.

 

[hfmckevitt]

Thank you everyone, as always your advise has be useful.

Henry
From
Linda Lee

 

[sdowney717]

I have 2 inverters, one is 3000 watt MSW, other is actually a modified UPS.
I mainly got the 3000 watt so I know it can start my fridge, run a microwave, run the boat PC and some lights.
I can also run my Princess oven, but not my Cruisair heat pump.

Never had issue with small chargers blowing up.
I run the inverter output into my entire boat system through a Hubbell GFCI. Leviton also is ok. Other GFCI may buzz.
I got a gen so the inverter is a silent backup.

The UPS backs up the bigger inverter, just in case so the navigation PC and some AC lights can run. My UPS mod was adding an interior fan, and exterior DC screw lugs to hook into the boat batteries.

Even created a remote on-off for it. Adding the fans it seems to have increased output by 50%. This was a free minuteman ups.

I had the metal panel from a salvaged broken inverter for free. I made the wooden control , it is a momentary switch and has an led. It still has a beep every few seconds when running on batteries but where it is located it is not too annoying. Both inverters are under the galley sink, the little one just piggybacks off the connection lug of the larger inverter.

 

[FF]

Operating underway with an engine on is very different from operating on batts for inverter selection.

Big units are less efficient at minor (REFRIGERATOR ) loads than ones that are smaller.

Just as 300HP diesels stink at making 25HP.

Inverter size makes little difference with a big alt , but not when on house batt power.

Weather the inverter is for use underway or anchored should be considered in your choice.

 

[kulas44]

My Slendide will not run on my ME2012 mod sign wave inverters. Also, have never burnt up a small cordless tool charger but have talked to plenty of folks that have. Sine wave or not doesnt make any difference on load carrying ability, most mod wave units have higher start capacity than tru sine units. My experience has been that bigger loads are easier to run that very small. I would approach the inverter issue as a complete unified installation, not as an add on. And no, a stand alone charger cant even get close to a 2000 watt inverter/charger in power, efficiency or cost.

 

[sunchaser]

An inverter/charger is one area where I think it's worth the larger up-front investment to get a quality unit with good capacity, that includes a charger. Once you start using it for one appliance, you will quickly succumb to the convenience and utility of having household-style power available. You will want to make coffee, and your wife will want to use a hair dryer. You will charge your phone and iPad and laptop, and you will be able to use power tools on board. .

Twistedtree likely knows more about inverters and associated electrical gear than the rest of us combined. Question Peter, how has living off the grid gone during this interesting NE winter?

 

[twistedtree]

Twistedtree likely knows more about inverters and associated electrical gear than the rest of us combined. Question Peter, how has living off the grid gone during this interesting NE winter?

I can let you know tomorrow. We have been in Seattle (more or less) at the boat for the past 2 months. My son has used the off-grid house a number of times recently and reported no troubles.

One of the funniest things happened about a year ago. There was a nasty tornado that came through and knocked down long swaths of trees and took out power most everywhere. A few days later the local power company truck came out to our house to let us know they were working on getting the power restored and it wouldn't be much longer.

 

[twistedtree]

My Slendide will not run on my ME2012 mod sign wave inverters. Also, have never burnt up a small cordless tool charger but have talked to plenty of folks that have. Sine wave or not doesnt make any difference on load carrying ability, most mod wave units have higher start capacity than tru sine units. My experience has been that bigger loads are easier to run that very small. I would approach the inverter issue as a complete unified installation, not as an add on. And no, a stand alone charger cant even get close to a 2000 watt inverter/charger in power, efficiency or cost.

My Splendide wouldn't run properly if my MasterVolt inverter/charger was even turned on. I could be on generator or shore power, and as long as the inverter/charger was turned on, the Splendide wouldn't run correctly. Of course both companies pointed the finger at the other. I think it's pretty ironic that the Splendide, which is targeted at RV and Marine applications here in the US, doesn't work in many situations with Inverters.

 

[twistedtree]

Twistedtree likely knows more about inverters and associated electrical gear than the rest of us combined.

You are very kind, but what's most important is that the buyer get something that best meets his needs. Hopefully everyone's collective experience here can assist him in making a decision that continues to look good a year after he makes the purchase, rather than one that seems good at purchase time but later proves problematic.

Some people are real minimalists on their boats, and if that works for them long term, then a smaller inverter will indeed be less expensive and likely waste less power in overhead. We like our boat to be like home without compromising what we can do. We pay a lot of attention to making things as efficiency as we can, but I want my microwave, dishwasher, TV, etc., and I don't want to have to load manage any more than absolutely necessary. So we have 7kw of inverter power. It's really overkill, but redundancy was a another key objective, so dual 3.5kw outbacks. What's nice is that one carries the load by itself up to a certain level while the other remains asleep with minimal power draw. The second one kicks in only when extra power is required.

It's currently a pure 120V system, but I am exploring rearranging it to be 120/240V split phase so I can run my washer and dryer (both are 240V) while underway without having to run the generator. But we'll see if that happens. It's a good bit more complicated when you really look at the details of what needs to be done.

 

[Phil Fill]

The Eagle had a charger inverter which I took out and replaced with separate charger and inverter. If you have a charger then only a inverter is needed. I bought a 3000 watt st Friday harbor for a couple hundred buck 15 years ago. Electric formula is amps X volts= watts. 3000 watts ÷ 120 volts = 25 amps max.

 

[JDCAVE]

It's currently a pure 120V system, but I am exploring rearranging it to be 120/240V split phase so I can run my washer and dryer (both are 240V) while underway without having to run the generator. But we'll see if that happens. It's a good bit more complicated when you really look at the details of what needs to be done.

Peter. WRT this comment. Do you follow James Hamilton's blog? He's put a fair it of effort into running his loads while travelling. I think with the air conditioners running whilst travelling in the tropics, his loads are quite substantial, I believe he runs everything from his large alternators.

This link summarizes what he did...

http://mvdirona.com/2014/08/a-more-flexible-power-system-for-dirona/


Jim
Sent from my iPad using Trawler Forum

 

[twistedtree]

Peter. WRT this comment. Do you follow James Hamilton's blog?

Yes, I follow the blog and have talked to him about his modification. Our objectives are similar, and really two-fold:

1) be able to run moderate 240V loads while underway with out the generator. Our alternators can support about 7kw, so that's our max sustained load while not draining the batteries. We don't want to run that way all the time, and I'd actually like to stay more around 5kw just to keep the current levels down. But that will support cloths washing and an AC unit or two, though probably not at the same time. But I figure if we are in heavy need of AC, I'll just run the generator.

2) More seamless operation with 50hz shore power. This isn't an issue until we leave north america, but that time is coming. But the idea is to be able to run 240V appliances that require 60hz off the inverter, and take shore power in via charger(s) that are frequency and voltage insensitive. Some of our 240V appliances can run on 50 or 60hz, like our how water heater and AC. But others are locked into 60hz like the washer and dryer and the oven. Bringing power in at 50hz and converting it to DC via a charger, then inverting to 60 hz 240V allows those appliances to run seamlessly. You just need to be sure your shore chargers keep up with the load, on average.

A third possible feature, but one I don't think we can take advantage of, is regulating/limiting your shore power draw. Lots of places only have 16A@230V, so about 3.6kw. If you limit the shore power draw to 16A on the charger, then you can avoid nuisance trips of breakers while still consuming more than 3.6kw on board. Your average load of course needs to be well under 3.6kw, but the inverter and batteries can handle short term loads in excess of the shore power limit, providing much more flexibility on board. We will be able to do some of this, but not all of our 240V loads will run through the inverter, the AC in particular, so we don't have a single device that can regulate the full load.

Anyway, this is getting pretty far off topic, so maybe we can pick it up in another thread if there is interest...

 

[koliver]

Henry:

Others have covered the inverter that you need. My thoughts are directed to your batteries. If you plan to run a household refrigerator, and other loads, you will need at least double the number of batteries that you would have without the fridge.

My own experience is the reverse of this. I took out a Norcold AC/DC unit and replaced it with a fridge run on a Danfoss DC compressor. I then reduced my battery supply to 1/2 of what had been inadequate to keep the fridge running. Now I have more than I need, and also run a 2nd Danfoss, in a small stand alone freezer.

 

[kulas44]

There is no way a DC compressor can be as efficient as a 120 volt ac compressor of the same type doing the same job. Thats my opinion, I need convincing. Would convert all my fridge loads to DC if I could be sold on it.

 

[koliver]

Guess it depends on what your refrigeration loads are.
I have what used to be a Norcold 8 cu ft box, powered by their AC/DC compressor. Changing to a Danfoss DC compressor resulted in much improved efficiency, so much that I was able to reduce my battery bank to 1/2 of what couldn't keep up with the demands of the old fridge. I have been happy with the Danfoss for almost 20 years now.

 

[Bay Pelican]

My Slendide will not run on my ME2012 mod sign wave inverters. Also, have never burnt up a small cordless tool charger but have talked to plenty of folks that have. Sine wave or not doesnt make any difference on load carrying ability, most mod wave units have higher start capacity than tru sine units. My experience has been that bigger loads are easier to run that very small. I would approach the inverter issue as a complete unified installation, not as an add on. And no, a stand alone charger cant even get close to a 2000 watt inverter/charger in power, efficiency or cost.

This is a known issue with the Splendide washer/dryers and the Magnum ME2012 inverter. The startup requirements of the Splendide are beyond the peak capacity of the inverter.

Magnum was very helpful with this issue and my solution was to upgrade inverters to the ME2812.

 

[Bay Pelican]

My Splendide wouldn't run properly if my MasterVolt inverter/charger was even turned on. I could be on generator or shore power, and as long as the inverter/charger was turned on, the Splendide wouldn't run correctly. Of course both companies pointed the finger at the other. I think it's pretty ironic that the Splendide, which is targeted at RV and Marine applications here in the US, doesn't work in many situations with Inverters.

Missed this post when I posted on the Splendide Magnum issue. What is the capacity / output of your MasterVolt inverter, and what is the peak output.

The Splendide units have a high start up demand which has been known for years (and which I understand is true of other washers). Back in 2002 I was warned that only the Xantrex 2000 pro among the smaller units had the peak capacity for starting a washer dryer. Both the Magnum 2800 and the Victron 2800 can power the Splendide at start up.

 

[FF]

" I have been happy with the Danfoss for almost 20 years now."

Although in the 2 decades Danfoss has gotten even better!

 

[twistedtree]

Missed this post when I posted on the Splendide Magnum issue. What is the capacity / output of your MasterVolt inverter, and what is the peak output.

The Splendide units have a high start up demand which has been known for years (and which I understand is true of other washers). Back in 2002 I was warned that only the Xantrex 2000 pro among the smaller units had the peak capacity for starting a washer dryer. Both the Magnum 2800 and the Victron 2800 can power the Splendide at start up.

The Mastervolt was 2500W I think. But the interesting part of the puzzle is that when the problems occurred, the inverter was not powering the washer. It was in bypass mode and passing shore power or gen power straight through. It also didn't matter if the Mastervolt was charging or not. It was clearly some sort of interference, but I was never able to sort it out, even whether it was conducted or radiated interference. I finally gave up and would just shut down the Mastervolt and throw the external bypass switch.

 

[markpierce]

Have a 24-volt DC refrigerator and a 120-volt AC air compressor for the air horn and wall plugs. The disadvantage of AC is that the air compressor won't work when the inverter is on the blink.

 

[Bay Pelican]

The Mastervolt was 2500W I think. But the interesting part of the puzzle is that when the problems occurred, the inverter was not powering the washer. It was in bypass mode and passing shore power or gen power straight through. It also didn't matter if the Mastervolt was charging or not. It was clearly some sort of interference, but I was never able to sort it out, even whether it was conducted or radiated interference. I finally gave up and would just shut down the Mastervolt and throw the external bypass switch.

That is the first I have heard of that problem. Questions: Did you try and run the washer just on the inverter? Does your inverter have a maximum 110v draw setting (maximum power it will take from shore or the genset)? If so at what level is it set? Unintentionally we set our maximum draw too low one time and the bypass was unable to power the tea pot.