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**Paul Elliott** · 26-10-2018, 11:04

Quote:

Originally Posted by ohgary

Just be carefull putting a bunch of USB charging ports around your boat unless you have a way to turn them off when not in use. They use a little power even when not being used.

My USB charging gizmos draw some current when unloaded, but it's very little -- well under 10 mA if I recall correctly. Mine get shut off when I'm off the boat, but the drain isn't enough to worry about (in most cases).

john61ct · 26-10-2018, 13:06

Efficiency losses from inversion are far greater than the spec sheet' "best case" numbers.

Get a Killawatt on the appliance, and a Watts-Up on the inverter input side and compare kWh over 24 hours to get the real scoop. No cheating turning the inverter on and off, unless that's part of your design for normal usage.

To the extent you can reduce the use of mains appliances, you will greatly improve your overall electrical system, and reduce costs both up front and ongoing.

Some may want dishwashers and induction cooking, fine and good if you're OK with the resulting costs.

But then energy efficiency is obviously far down on the list of priorities.

ohgary · 26-10-2018, 13:34

Quote:

Originally Posted by Paul Elliott

My USB charging gizmos draw some current when unloaded, but it's very little -- well under 10 mA if I recall correctly. Mine get shut off when I'm off the boat, but the drain isn't enough to worry about (in most cases).

Very true, A single unit doesn't use much power but when you total up all the wall warts, chargers people have now a days, they can add up.

john61ct · 26-10-2018, 14:26

Only relevant with a boat literally in storage without any charging.

In which case bank should be fully isolated.

Much less than the bank's self-discharge rate.

SV_Harbinger · 26-10-2018, 18:55

I try to keep everything I can in the 12v world, for simplicity. The TV is 12v I don't remember what I paid exactly for it but it's a 34" I think and the only complaint I have with it is that it is a little on the quiet side, and the blender, just about my only electric appliance is 12v, not as strong as a 120v but does a good job on the light ish work I throw it's way (margaritas are better with crushed ice IMHO) and I can make frappes on the occasions that I have ice cream aboard (vanilla and chocolate ice cream and coffee Brandy make a surprise worth having on a hot evening) my other major 12v thing is a vacuum (an upright stick type) and it has enough suck to clean up after me satisfactorily (from a local vacuum shop I had asked if they had ever seen one l, they said no but they could make me one if I wanted)
I do have 2 inverters on board if I want/need them but they get rare use as they are pretty much only for running power tools which does not happen all that often when on the mooring/hook but, they are nice to have when I need/want to use something like a jig saw or sander.
So there are things you can do without needing to invert your power and for what it's worth I use the "car charger" hookups for my phone and the like as to the relative efficiency of inverters I couldn't really say...

tanglewood · 27-10-2018, 04:19

Quote:

Originally Posted by Dockhead

Why so snide? You might try for just a second to understand what he was saying.

He meant -- if the frequency is the same, then there is no reason to incur the loss in converting down to 12v (or 24v) and then inverting back up.

In that case, you just run it through a transformer, like my Victron isolation transformer.

If you need a different frequency, however, then Tanglewood is correct -- doing what the OP was asking about, is very common on larger boats, just like Tanglewood said.

On a boat for example with 230/24 50hz inverter/chargers (one, or a gang of them), you just add a large 110/24 battery charger (or several of them).

You isolate the inverter/chargers from the shore power system, connect to that ONLY the battery charger(s), and Bob's your uncle.

I think MOST large world cruising boats are set up like that.

On large loads, quality chargers and inverters can be more than 95% efficient, so the two-way loss might be only 10% or so. On small loads, you don't care, seeing as how you're on shore power. It's a fine solution.

Thanks for clarifying that for me.

Yes, I meant no conversion losses because you are not converting, but rather using the native frequency shore power directly. To use non-native frequency shore power, you need to convert and incur the losses. Damn physics.

tanglewood · 27-10-2018, 04:37

I certainly understand the approach of running everything (nearly) on 12V, and avoiding inverter losses. But keep in mind that there is a whole spectrum of use cases on boats, driven by how one wants to operate, and with what conveniences. When you start adding equipment, it pretty quickly becomes much cheaper and easier to use off-the-shelf AC appliances and gear rather than specialized marine or RV 12V equipment. And pretty soon you reach a tipping point where you just want AC power all the time, period. Then you have an inverter running all the time.

Also keep in mind that using more power doesn't have to equate to wasting it. We have always been fanatic about selecting efficient appliances, looking very carefully at standby power draw, and operational efficiency. Yes, we have AC refrigeration, but we have carefully selected them to be as efficient as possible and still meet our operational goals. Charge adapters have been discussed, and they can be very good, or very bad. Older designs have big transformers and are inefficiency, where newer ones are high frequency, lighter, and much more efficient. We pick them carefully. Same with computers, and entertainment devices. Entertainment stuff like TVs have gotten much better over the years thanks to Energy Star ratings. Many used to remain on drawing nearly full power even when "turned off". Evil. And things like satelite boxes are among the worst. My KVH consumes more power than all my refrigeration combined. Shame on them.

Anyway, my point is that using power isn't the same thing as wasting power. You can choose to use less or more - it's up to you. And you can choose to use it constructively, or watch it vanish as waste heat - it's also up to you.

**Dockhead** · 27-10-2018, 05:35

Quote:

Originally Posted by hellosailor

Dockhead-
OK, if you have the right equipment and it is set up properly (which will also mean at least two inverters, because unless I was misinformed again, they are not efficient at partial especially light loads) you'll only have a 10% loss. That's still "real money".
And even a transformer, even a 1:1 transformer, surely still has SOME losses in it?

Using the shorepower direct, no losses except that of the wiring drop. Using conversions...not the same.

Sure, but you can't use shorepower direct if you have incompatible frequency. That is what this whole thread is about.

You don't need two inverters -- don't forget, we're talking about being on SHORE POWER. Nobody cares about saving 4 or 5 watts by switching between large and small inverters while they're on shore power. That is "real money" only when you're on battery power, and that's not what this conversation is about.

**Dockhead** · 27-10-2018, 05:45

Quote:

Originally Posted by john61ct

Efficiency losses from inversion are far greater than the spec sheet' "best case" numbers.

Get a Killawatt on the appliance, and a Watts-Up on the inverter input side and compare kWh over 24 hours to get the real scoop. No cheating turning the inverter on and off, unless that's part of your design for normal usage.

To the extent you can reduce the use of mains appliances, you will greatly improve your overall electrical system, and reduce costs both up front and ongoing.

Some may want dishwashers and induction cooking, fine and good if you're OK with the resulting costs.

But then energy efficiency is obviously far down on the list of priorities.

You can understand the cost of running an inverter pretty well by understanding what kind of overhead it has. If it runs with low loads, it will eat a lot of power -- as a percentage of what you are using. But if you think of it rather that the inverter burns 20 watts as long as it is turned on and not in power save mode -- that is, when there are at least some small loads on it -- then you have a better idea.

What is uncomfortable from a systems point of view is having just a couple of significant electrical appliances and not too much storage or supply. Then you're juggling it all the time. If you go whole hog and just install all the gear you need, then storage and generation capacity to match, it actually becomes much easier to manage. It becomes much easier to combine loads to suit what is going on, for example, and it's just not a big deal to have some computers and chargers running on AC power. A dishwasher, by the way, would be an absolutely great thing to have on board (I don't have one, but want one on the next boat). Saves a lot of water, better hygiene, simplifies process of serving meals.

I run my own ship's computer, monitor, laptop computer charger, phone charger, 4g/wifi router, off 24v. That way, I can do basic functions, especially when I am alone on board, without turning on the inverter. But once there are 4 or 5 people on board, then it doesn't matter -- I just leave the inverter on 24/7 and generate as necessary.

Cherod · 27-10-2018, 05:59

( please excuse my ignorance here ) , i am presently considering fitting an invertor onto around 400 amph battery bank, i appreciate that that will not be enough to run a lot for a long time so am wondering is it alright to run the engine to keep the charge up in the batteries while runing the invertor ,, ( considering 2/3 k invertor ) , thanks , R.

**Dockhead** · 27-10-2018, 07:02

Quote:

Originally Posted by Cherod

( please excuse my ignorance here ) , i am presently considering fitting an invertor onto around 400 amph battery bank, i appreciate that that will not be enough to run a lot for a long time so am wondering is it alright to run the engine to keep the charge up in the batteries while runing the invertor ,, ( considering 2/3 k invertor ) , thanks , R.

Of course it's all right. If you have a decent sized alternator, then you can run the whole boat off the inverter as long as the engine is running.

When we're motoring, life is just like being on shore power, on my boat.

Nicholson58 · 27-10-2018, 08:52

Quote:

Originally Posted by a64pilot

Inverters can be over 90% efficient.
However there is an overhead if you will with them, so if your powering up a 3 KW inverter to charge your laptop, it’s very inefficient, reason is that a 3 KW or so inverter eats about 20 W (1.5 AH) or so just sitting there turned on, delivering no power.
I bought the smallest pure sine inverter I could find to power my TV / Satellite receiver, and save the big one for big jobs, like running the vacuum cleaner etc.
https://www.solar-facts.com/inverter...efficiency.php

Good inverter efficiency is in the upper 90%. What that generally means is that the idle loss for a 95% efficient 3 kW inverter will be 5% of 3000 watts = 150 watts of loss (heat). We use this for the shop vac, coffee maker and other appliances. If we forget to turn it off, the drain is readily apparent. For this reason, we have a 300 watt 98% efficient full sine inverter for everything with a wall wart. 2% of 300 = 6 watts lost. Not much, but when we turn it on we line up all devices.

Cherod · 27-10-2018, 09:31

Quote:

Originally Posted by Dockhead

Of course it's all right. If you have a decent sized alternator, then you can run the whole boat off the inverter as long as the engine is running.

When we're motoring, life is just like being on shore power, on my boat.

thank you..

GrowleyMonster · 31-10-2018, 10:07

Just have a 220v battery charger on board and a portable 50hz 220v air conditioner for nights alongside a dock with 50hz 220v power. Stick the exhaust duct out a porthole and run a piece of hose to bilge, for the condensate. It's only electricity. Don't let it get your garters in a twist.