Energy solutions onboard a live aboard

[Dockhead]

Originally Posted by a64pilot

How big is it? I doubt the overhead is ten watts, but maybe since it’s a 24V inverter?
I say that cause if you look at quality inverters, 10 Watts for each 1.5 KW seems to be a standard, but I’ve only looked at 12 V inverters

Well, you can look up the Victron specs.


Efficiency is a little less for the 12v model (93% vs 94%) but the overhead is the same.


That being said -- the Victron is an expensive, complex unit with heavy transformers (rather than switching transformers). It may be that not all inverters perform like this.


Not only is the overhead 10 watts, but the Victron has "search mode", so it will shut itself down automatically if there is no load, and send short very low power pulses to "search" for a load so that it will automatically switch itself back on. Using less than 10 watts in this mode. It's designed to be left on 24/7 and it works well like that, if you have reasonable battery capacity.

[a64pilot]

Magnum has a search mode as well, I just haven’t bothered.
I just turn it off, only things I have that I use that require significant 120 VAC are intermittent, or require the generator.
I used to leave it on just so we had power when we wanted it, then discovered it cost me over 30 AH to do so, and not having to push a button isn’t worth 30 AH to me.

[john61ct]

My point is that actually measuring IRL DC wattage drawn by the inverter,

and comparing to the AC watts drawn by the device,

calling the mfg published efficiency specs "optimistic" is very generous.

Of course the better (more expensive) units will usually be more efficient.

But IMO best to just avoid inverters whenever possible.

In my use cases that is nearly all the time.

But then I do not strive to duplicate a mod con lifestyle when off grid.

And even in a mains-connected S&B context, have never owned a dishwasher or clothes drier for example.

[Dockhead]

Originally Posted by john61ct

My point is that actually measuring IRL DC wattage drawn by the inverter,

and comparing to the AC watts drawn by the device,

calling the mfg published efficiency specs "optimistic" is very generous.

Of course the better (more expensive) units will usually be more efficient.

But IMO best to just avoid inverters whenever possible.

In my use cases that is nearly all the time.

But then I do not strive to duplicate a mod con lifestyle when off grid.

And even in a mains-connected S&B context, have never owned a dishwasher or clothes drier for example.

A great deal depends on what kind of consumption you have. If you are using one device at a time, then whatever the real life efficiency, it doesn't make much sense to fire up a large inverter. If on the other hand you have a lot of people on board and a lot of different devices, you get synergy in covering the overhead, and anyway you are pumping a lot of power through the system so +/- 10 or 20 watts just doesn't move the needle.


So as with so many things -- different use cases put these systems architecture issues into completely different lights.

[Subtandard]

I have not seen anyone ask what size boat you have. Solutions are different for a 30 footer than they for a 60 footer. I do not use any 230V appliances unless I have shore power. My computer (doubles as a TV) runs on 12V. My tablet and cell phone charge from the USB charging port on my solar controller. If I had 600AH of batteries I might do things differently but I live on a 35 foot boat.

[Frugal]

After toasting a couple of 250 volt computer chargers by using a modified sine wave inverter I have resorted to a small DC / DC converter. Bought a few with the thought of poor quality and short life span but the original is still going well after five years of constant service powering a 19.5 volt laptop.
The manufacturer suggests if you are seeking more than 6 amps out of it you may need to enlarge the heat sinks.!!
Cheers



https://www.ebay.com.au/itm/DC-DC-10...0AAOSw5P9bKSnH

[conachair]

Originally Posted by Frugal

After toasting a couple of 250 volt computer chargers by using a modified sine wave inverter I have resorted to a small DC / DC converter. Bought a few with the thought of poor quality and short life span but the original is still going well after five years of constant service powering a 19.5 volt laptop.
The manufacturer suggests if you are seeking more than 6 amps out of it you may need to enlarge the heat sinks.!!
Cheers



https://www.ebay.com.au/itm/DC-DC-10...0AAOSw5P9bKSnH

Been using the same one for a few years now. Works fine.

[GrowleyMonster]

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

THIS. Nailed it.



A small inverter for small stuff. A big inverter, if needed, for the big stuff. Turn on only the one that is needed, and turn it off when you are done. Pure sine wave inverters have gotten very efficient lately, and the price has come down enough that there really isn't much point in buying square wave or "modified sine wave" inverters anymore. Consequently, there is no appliance that you need to worry about running from an inverter of sufficient size.



Cheap Chinese sealed DC/DC converters are all over the place, and you can easily wire a bunch of USB charging ports for your boat, to keep your tablets and phones charged. Or other uses. My bank is 48V and I run all 12V and 5V gear from DC/DC converters and I have two inverters, a 300w and a 3kw one which I seldom use except for power tools.



If you really want to improve your electricity availability, add the biggest solar panel array you can carry, and invest in more and bigger batteries. Be sure and read up on boat electrical systems and learn about charging, control, maintenance, and monitoring of them or it will be money wasted. You might consider an alternator upgrade on your diesel, too. When you run the diesel just for charging batteries, you want to go ahead and load the engine properly, and only run for a minimal length of time. Get the best shore power charger you can afford. Learn the pros and cons of multiple banks and separate start batteries. Get a Kill-a-Watt or similar usage meter that plugs into your receptacles so you can write down the energy used by various devices. You may have some that you will decide are not worth having aboard, or could better be replaced with DC or diesel or propane appliances. Seriously, you could spend a couple of years studying boat electrical and battery systems, and not a minute of it would be wasted.

[mfahrenthold]

Who uses 230 volts on a boat? And why? Never heard of this. Everything we have is 120 volts or 12 volts. In 30 years of owning boats I have never heard of 230 volts on a boat. Just wondering.

[Subtandard]

Originally Posted by mfahrenthold

Who uses 230 volts on a boat? And why? Never heard of this. Everything we have is 120 volts or 12 volts. In 30 years of owning boats I have never heard of 230 volts on a boat. Just wondering.

Outside the Americas, nearly everyone use 230V 50Hz.

[john61ct]

AKA 220–240 volts at 50 Hz

[hellosailor]

"Who uses 230 volts on a boat? And why? Never heard of this. Everything we have is 120 volts or 12 volts."
That's an odd boat. The US national standard calls for something odd like 117VAC actually, with a pretty side allowance of about 10% IIRC. Buildings are often supplied with either 230 volts split into two 115V legs, or 220 or 240, depending on legacy factors with the local power company.
In one of the last big blackouts in NYC, you would find streets in the outer boroughs where the homes on one side were powered from a separate system than the other side--and one got power while the other went black. Legacy equipment from different distribution points.
Your "12" volt equipment also had better not be 12 volts. Alternator/engine power is typically 13.8-14.4 volts, and equipment is designed for that higher voltage. Real "12" volt equipment would just burn out.

The point being, there are many standards, lots of different nomenclature, and very often the "standard" voltages we know are simply incorrect, the result of "round numbers" being grabbed and other factors.

Apparently the first power stations in Europe (Germany?) ran at 100V 50 Hz. Because 50Hz is much less efficient than 60Hz, in both generation and transmission, they decided up to the voltage to compensate for the losses.
And the original choice of 50Hz was made because "60" doesn't fit neatly into a metric system, where things should be in orderly multiples of ten.

[Reefmagnet]

We've got 5v usb outlets all over the boat - the kind with dual outlets. My tip here is to buy the ones that glow red rather than other colours and make sure both outlets can supply 2.4 amps consecutively as some units have a 2.1/1.0 amp output only. We've also got 12 to 19 volt DC to DC converters for the laptops. Oddly enough, getting regulated 12 volts from a 12 volt house supplying is the most difficult, but there are converters available that can do this.

Another fan of having dual inverters. Like diesels, they are more efficient when operated at the top end of their range. The top quality 600 watt unit's power is distributed throughout the boat and includes a remote control and good monitoring. It's idle current is low. The cheap and cheerful full sine wave 1500 watt unit has it's own power outlet and power switch in the galley and is used for the toaster and anything else needing more grunt then the smaller inverter can supply.

[newhaul]

Originally Posted by hellosailor

"Who uses 230 volts on a boat? And why? Never heard of this. Everything we have is 120 volts or 12 volts."
That's an odd boat. The US national standard calls for something odd like 117VAC actually, with a pretty side allowance of about 10% IIRC. Buildings are often supplied with either 230 volts split into two 115V legs, or 220 or 240, depending on legacy factors with the local power company.
In one of the last big blackouts in NYC, you would find streets in the outer boroughs where the homes on one side were powered from a separate system than the other side--and one got power while the other went black. Legacy equipment from different distribution points.
Your "12" volt equipment also had better not be 12 volts. Alternator/engine power is typically 13.8-14.4 volts, and equipment is designed for that higher voltage. Real "12" volt equipment would just burn out.

The point being, there are many standards, lots of different nomenclature, and very often the "standard" voltages we know are simply incorrect, the result of "round numbers" being grabbed and other factors.

Apparently the first power stations in Europe (Germany?) ran at 100V 50 Hz. Because 50Hz is much less efficient than 60Hz, in both generation and transmission, they decided up to the voltage to compensate for the losses.
And the original choice of 50Hz was made because "60" doesn't fit neatly into a metric system, where things should be in orderly multiples of ten.

Hence the use of the term "nominal" when refering to electrical voltages.

[Uncle Bob]

Originally Posted by mfahrenthold

Who uses 230 volts on a boat? And why? Never heard of this. Everything we have is 120 volts or 12 volts. In 30 years of owning boats I have never heard of 230 volts on a boat. Just wondering.

Don't get out much do you.