Charging At Anchor

kulas44 said:

So, bout 9 hp, not such a big deal but more than just about any other alt. available. A 15 kw gen needs about 20 hp so its a decent trade. Unless of course you factor in running the main at lower than optimum loads, then 9 hp is a net gain, unlike the gen, which is total loss. If you have 2 of these you can run all of the ac load you could ever need, as in a twin engine boat. I have found that when I run all day without the ac on it takes hours to get the inside temps liveable in the summer due to heat soak from the engines. With the big alt.s you can crank the cool down and keep a better load on your mains. Win Win.

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I agree with you.
Only problem is I run ( 240V ) A/C . I have not come across 240vac inverters that have a neutral conductor.
I'd be happy if I could find a 3000watt @ 240vac

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A pair of 2000 watt ME2000s with an interface cable will make 240. A neutral conductor is not really required, just a case ground. But, you can run a neutral if you want. However, if you want to run ac loads underway you will need much more inverter power, about 10 kw or so. And a battery bank to go with it. You cant expect to replace a 15 kw gen with a 3000 watt inverter.

How about the Magnum Energy MS4024, 4000 watt, 24 volt pure sine wave 120/240 inverter. A pair of these would be about right. But, one will do 240 volt ac. 240 is available from most of the bigger inverter makers.

Mbevins

Since you are planning for the loop, why not keep your life simple and do as hundreds of us distance cruisers do and use a quality alternator with a Magnum, Victron or other good inverter charger? You then can add batteries to suit your overnight needs.

I may have missed it in the last many posts but what does your current vessel have for an alternator, inverter and genset? Is it currently a 12V or 24V system for instruments, fridge, lights etc ?

RickB
Thanks for link. I had completely forgotten about this solution.

Sunchaser
I have a 44 Viking ACMY . DD 671's . 50A 240vac system.
Genny only. Boat is primarily AC powered with a few 12DC lights. (Pumps and such excluded) .

One of my Loop preps is to add an inverter. As your aware looping is done primarily at HS. For me that's 800rpm.
This means I need to charge at that rpm which presents its challenges. But not overly difficult.

I was going where you suggested when the 50 dn alternator was suggested. I believe it suits my application well if I can make it work. One of the benefits is I can stick it at the back out of my way. The ER is spatially challenged. It does mean adding 24vdc to the boat, but In this case I don't think it matters as it is an isolated system.

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I'm going to throw out some experience based on designing and fixing shipboard systems over many years: Big inverter systems are problematic. Owners install big inverters, big batt banks and big alternators at substantial cost, weight and complexity all for the sake of avoiding running the genny. After a few years of problems and more cost, they realize it is just better to run the genny. So the inverter just becomes a very big and expensive battery charger. No one made decent schematics of system, so it becomes another expensive adventure for the next owner.

My take on this: Don't bother trying to size inverter system to run any aircon. Too much load. Too much engineering needed to make it work.

It is ok to run fridges, freezers, icemakers and other little loads on inverters. So size for that. Probably can be done with 1500w or so. A smallish bank can handle that for overnight, and normal alternators can handle that with mains on and genny off.

If you need aircon or elec stove or hot water or any big load, run the genny. They like to run, too.

Ski in NC

I do agree with your statement. I have no aversion to running the genny. In fact since all the support equipment (stove etc) are 240vac I just took it for granted that I'd not have access without the genny.
My suspicion is that going to a proper 240v inverter system is not only problematic but cost prohibitive.

I'm still interested in the 50dn though for my reasons stated above.
I should also add I've owned this boat for 12 years and have gotten along quite nicely with just the genny. I just think it makes sense to do this for the # of miles we do on the Loop.

One question I'm still wrestling with is do I really need the charger option?

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On my personal boat, I have a dedicated charger and a dedicated inverter. I chose not to combine the two devices. It seemed at the time getting a unit that combined the two features cost more that the two separate.

I have never seen or worked on the 50DN, but looked it up on line and it seems like an impressive machine. It uses step up gearing to get rotor speed up even at idle (but not the belt drive version). Seems like a perfect machine for a 71, if it can physically fit.

Is the 50DN available in 12v?

Ski in NC said:

On my personal boat, I have a dedicated charger and a dedicated inverter. I chose not to combine the two devices. It seemed at the time getting a unit that combined the two features cost more that the two separate.

I have never seen or worked on the 50DN, but looked it up on line and it seems like an impressive machine. It uses step up gearing to get rotor speed up even at idle (but not the belt drive version). Seems like a perfect machine for a 71, if it can physically fit.

Is the 50DN available in 12v?

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So far I haven't come across anything to indicate that it is available in 12vdc. That is the one drawback. It forces me to use 24vdc. In theory it should help the battery situation but I haven't done the math yet to confirm.

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Is the 50DN available in 12v?

YES , fitted to buses from the 1960 era when there were few 24v anything.

IF the alt output will be fed to an inverter so air cond can be had underway a huge alr will be needed.

For most boats the batt bank will only require the output of a std truck 135A alt for a modest time.

135a is 25% of a pretty good sized bank .A pair would be overkill for most .

mbevins said:

It forces me to use 24vdc. In theory it should help the battery situation but I haven't done the math yet to confirm.

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Why not charge in series and load in parallel?

RickB said:

Why not charge in series and load in parallel?

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Then you could not run the inverter while charging with an alternator. And more complicated switching.

Why not?

Please explain.

Perhaps a diagram would be in order?

If you charge two 12v batteries in series with a 24v source, and try to draw 12v off one of the batts, the charging of the two batts will be inequal. The loaded batts volts will drop, the unused 12v batts volts will rise. One batt will go dead, the other will cook out. A common mistake in configuring 12 and 24v systems.

You could use a 24v to 12v converter.

Who said you have to have "unused" 12V batteries?

You can have (for the sake of argument) 2 12V batteries in series to supply 24V or receive a 24V charge.

If you parallel the 2 12V batteries you can power a 12V load with a (for all practical purposes) balanced drain on each 12V battery.

(just noticed I did not mention that floating the batteries is not possible in this configuration)

ON coaches with 24V engines and all the rest 12V the std is ,,

Inverter Charger, Power Inverter, Battery Equalizer, Battery Monitoring

www.vanner.com/‎

I use a system with 2- 12V start batts , and the Vanner feeds 2 12V batts used as house batts.

This does require a rotary switch to stop the start batts from attempting to keep up the house batts while overnight camping with out a power pole..

The >house< batts are effortless storage for an IO batt pair used only in summer.