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Old 10-08-2013, 12:50   #16
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Re: 12v system for everything?

I have both systems aboard and I am not throwing out one in preference to the other, I personally don't care to have the generator running anymore than needed.
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Old 10-08-2013, 13:07   #17
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Re: 12v system for everything?

12V is good, but I would invert for a few things as well; TV, Vacuum Cleaner, certain charging devices. A small powerful vacuum is indespensible for cleaning up after those many unplanned repairs or modifications! (one gal shop vac)
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Old 10-08-2013, 13:15   #18
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Re: 12v system for everything?

Spend most of my days only using 12 volts including refrigeration. Two 75 watt solar panels meet my needs. Though I do have a Honda 2000 generator on board if I do need 120 volts for tools or charging my 48 volt electric propulsion battery bank. But, once at anchor 12 volts is pretty much all I use.
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Old 10-08-2013, 13:23   #19
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Re: 12v system for everything?

Quote:
Originally Posted by Rick R View Post
The only things that I can think of that you would need AC for is a microwave, air conditioner, and also maybe a fridge, since DC fridges are much more expensive than AC ones.
Power tools

Soldering iron

Heat gun

Vacuum cleaner

Convection oven

Toaster (so much more convenient and better results than toasting in the oven)

Hot plate (in case gas runs out)

Television (very little choice in 12v televisions)

Electric kettle (extremely handy)

Coffee machine (you can make regular coffee on a gas stove, but harder to do espresso)

Chargers for a multitude of handheld devices (computers, tablets, cameras, phones, radios, power tools, etc., etc., etc.). Some of these can be charged from DC, but it's not always practical to have DC chargers for everything, especially when you have guests

Electric heaters (extremely handy when you're on shore power)


It's possible to avoid AC power on board, of course (it's possible to avoid any power at all if you really want to), but why? It's extremely useful, and AC power (especially 230 volts) is a much more efficient way of transporting energy around the boat.

I do not keep my boat in a marina and rarely have shore power, but with a decent diesel genset, battery bank, and charger/inverter, AC power on board is no problem.
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Old 10-08-2013, 14:06   #20
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Re: 12v system for everything?

I have lived without inverters before and can do it again, but I choose not to.
120V AC fridge and freezer $500. 12V Fridge and freezer $3000.
120 V AC lighting fixtures $10. 12V DC lighting fixtures $35 and the same theme goes on.
MY $4 Flourescent light screw in bulb lights up my area much much better than my $35 LEDS (BTW< I do have both).

If my inverter craps out, all will be the same as if I never had it except for my fridge.
I run both 120 AC and 12V DC
We live aboard and have been for 15 years or so.
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Old 10-08-2013, 14:07   #21
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Re: 12v system for everything?

The real problem with inverters is they are not efficient at low power output or when idling with nothing turned on. It takes energy to convert DC to AC above and beyond what the use demand is. The fewer AC appliances that you have and less need for an inverter the less generating capacity you need. For daily use, 12v is way way more efficient than 110/220 through an inverter.

I've set my boat up with 12v low drain as much as possible. Have a 1700 watt inverter that i turn on for specific AC tools but only when needed. Also have a little inverter I use to charge electronics that won't plug directly into the boat's DC power. The small one doesn't have the idle draw of the bigger inverter but isn't as efficient but draws less power. Been at a dock without AC power for several years and it works just fine. Have two 130 watt solar panels that are left in the vertical stored position because I don't need the generating capacity.

FWIW, all tv's run off dc power. They either have a DC converter brick or an internal DC power supply. If you can find one with a brick, you can convert it to DC by cutting off the brick and feeding with the voltage required. May work off straight 12v from the batteries or need a DC/DC converter to match the voltage required. Unfortunately, TV manufacturers are leaning toward internal power supplies which requires way more technical skill that most of us possess to run on ship's power. All battery powered devices whether it be tools or electronics can be charged from the boat's batteries. Because contractors need their tools at sites without electricity, the tool manufacturers sell cigarette lighter power socket chargers. Anything you buy with a brick can be charged by supplying the right voltage via a DC/DC converter if it won't work off of straight 12v.

We lived for more than 10 years in a house powered by a heavy duty 2500 watt inverter. Had to go with straight AC because we built the house for conventional power but the deal to bring it down to our building location fell through. The inverters inefficiency was a killer. Even though it had a demand auto on function, running it at low power after sunset for things like lights, depleted the batteries fairly quickly. If we'd known and could have set up the house for 12v, probably would still be on solar.

Maybe some day I'll have a boat with a machine shop so i can have my Drill Press, Table Saw, Air Compressor, Stationary belt/disc sander, etc. but highly doubt it.
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Old 10-08-2013, 18:28   #22
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Re: 12v system for everything?

Quote:
Originally Posted by roverhi View Post
The real problem with inverters is they are not efficient at low power output or when idling with nothing turned on. It takes energy to convert DC to AC above and beyond what the use demand is. The fewer AC appliances that you have and less need for an inverter the less generating capacity you need. For daily use, 12v is way way more efficient than 110/220 through an inverter.

I've set my boat up with 12v low drain as much as possible. Have a 1700 watt inverter that i turn on for specific AC tools but only when needed. Also have a little inverter I use to charge electronics that won't plug directly into the boat's DC power. The small one doesn't have the idle draw of the bigger inverter but isn't as efficient but draws less power. Been at a dock without AC power for several years and it works just fine. Have two 130 watt solar panels that are left in the vertical stored position because I don't need the generating capacity.

FWIW, all tv's run off dc power. They either have a DC converter brick or an internal DC power supply. If you can find one with a brick, you can convert it to DC by cutting off the brick and feeding with the voltage required. May work off straight 12v from the batteries or need a DC/DC converter to match the voltage required. Unfortunately, TV manufacturers are leaning toward internal power supplies which requires way more technical skill that most of us possess to run on ship's power. All battery powered devices whether it be tools or electronics can be charged from the boat's batteries. Because contractors need their tools at sites without electricity, the tool manufacturers sell cigarette lighter power socket chargers. Anything you buy with a brick can be charged by supplying the right voltage via a DC/DC converter if it won't work off of straight 12v.

We lived for more than 10 years in a house powered by a heavy duty 2500 watt inverter. Had to go with straight AC because we built the house for conventional power but the deal to bring it down to our building location fell through. The inverters inefficiency was a killer. Even though it had a demand auto on function, running it at low power after sunset for things like lights, depleted the batteries fairly quickly. If we'd known and could have set up the house for 12v, probably would still be on solar.

Maybe some day I'll have a boat with a machine shop so i can have my Drill Press, Table Saw, Air Compressor, Stationary belt/disc sander, etc. but highly doubt it.
This is an overly simplistic analysis. Almost all electronic devices today contain switched mode power conversion inside. Often supplying several voltages to different subsystems. Hence converting to 12 V via DC DC convertors isn't in itself any guarantee that the efficiency of powering the device will increase. modern SWPS have efficiencies approaching 98%, simply removing that power block and assuming that the DC can be fed in, will not bring much of an improvement, and will expose the internal power conversion directly to the nasty 14v battery system.

Then you have AC motors , these are high efficiency , higher then DC, so converting them to run on DC does not result in benefits.

SO the real answer is that a mix of power devices suitable for the job is better then dogmatic application of an ideology. AC for areas where AC is good.

Invertor quiescent power is a complex topic. Good ( read expensive ) design can minimise such power loss. often cheaper switched modes can be wasteful when running at low loads, it oftens pays to have two inverters circuits for high and low power etc.

AC has its place, just as DC has. in my view actually 24V DC or 48vDC would be actually better then 12VDC anyway.

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Old 10-08-2013, 18:57   #23
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Re: 12v system for everything?

My boat is all 12 volt and I only use cordless hand tool, I carried a Honda 2000 watt gas generator for a big drill, grinder and other stuff when the cordless were all 12volt now with 18 volt and more I sold the generator and leave all the corded tools ashore, I do use a small inverter to charge tool batteries because 12 volts won't charge a 18 volt battery, but its tiny, cheap and I charge on slow, not rapid charge.
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Old 10-08-2013, 19:22   #24
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Re: 12v system for everything?

My DeWalt 12 v charger will charge my boss' DeWalt 18v batteries; the label says so and it does.
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Old 10-08-2013, 19:28   #25
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Re: 12v system for everything?

My DeWalt 12 v charger for 14.4 v tools will charge my boss' DeWalt 18v batteries; the label says so and it does. Also, I took apart an old 14.4 v battery pack and wired 12 volts from my boat's batteries to it to run my 14.4v drill.
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Old 10-08-2013, 19:33   #26
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Re: 12v system for everything?

All depends on how big the boat is. It is more difficult / impossible to go pure 12V on bigger ones. Do not tell Ferdinand tough, he could take offense.

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Old 10-08-2013, 22:46   #27
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Re: 12v system for everything?

My new Chinese Invertor, Pure Sine Wave, 12 volt, 5000 watts, 10000 watt Surge, 240 volts, Runs my 500 watt cord drill and my 5 inch cord grinder at the same time and loaded heavily, Easily,
From my two house bank batterys,

It wont run my invertor welder,

Why waste power keeping a Tool Battery Pack charged, Just plug your corded tools in to the invertor, Run your tools and thats it, No wasted power,

I had 280 watts of Solar, Wind Gen, and the Diesel, No Generator, Never ran out of power, But the micro wave did suck it, So didnt use it very often, In Rough water for coffee only,

Hot water ran off the main diesel, Gas fridge and stove, Gas tanks last about 3 weeks, Fill them up before you leave,

So covers most crossings, Swap and go cylinders, $20-00 a cylinder, or there abouts, Longer crossings, More cylinders, Same as food, Keep two or three weeks in reserve, Canned, Long life Milk, Pauls is actually nice to drink, It doesnt have that long life horrible taste,
I can buy 12 volt gear here cheaper than 240 volt, But I dont buy it from a Marine store,

A big car and truck Battery store, will have all the trick bits you want, At a price you can afford,

Or, shock Horror, You can buy it off the internet from China, For a pittance, compared to the price gougers here,
And its good gear too,
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Old 10-08-2013, 23:39   #28
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Re: 12v system for everything?

Yes you can go all 12v with small inverter for TV or 2, laptop or 2 and power tool or 2.

We've cruised 3.5 years and anchored out most of the time using solar power only, and we have very little that runs on AC.

In fact, our 600 watt pure sine wave inverter provides all of our AC power for our TV, surround-sound stereo, 2 laptops, vacuum, charging all our little gizmos like toothbrushes, etc.

The only appliance that needs more is our microwave. So our 2500 watt inverter gets turned on only when we run the microwave. We don't have air conditioning (it would require a generator). Here's our setup:

Solar power installation on a sailboat
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Old 11-08-2013, 01:56   #29
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Re: 12v system for everything?

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Originally Posted by goboatingnow View Post
Hence converting to 12 V via DC DC convertors isn't in itself any guarantee that the efficiency of powering the device will increase. modern SWPS have efficiencies approaching 98%, simply removing that power block and assuming that the DC can be fed in, will not bring much of an improvement, and will expose the internal power conversion directly to the nasty 14v battery system.
In practice getting rid of the 12v -inverter-DC brick and replacing it with 12v-DC to DC converter usually results in about 20-30% lower power consumption.
Getting rid of the 12v -inverter-DC brick and replacing it with a direct 12v feed is about a 50% saving.

These are very worthwhile improvements for a boat, they can result in very low power consumption such as 21 inch screen I use for movies and occasional computer work that consumes under 1A direct from the boat supply.

Trying to run very high powered devices like microwaves from DC does not make sense even assuming it is possible (its not usually). Nor is it important to fuss about infrequently used items like soldering irons. Even large savings in % terms will make very little impact on your overall power budget if its only used occasionally.

It is however, very worthwhile making all your commonly used items run without the inverter. This is especially true when powering your boat from solar/wind.

With these sort of discussions we do see some polarisation of views. The generator equipped boats cannot understand why we fuss reducing power consumption by a few amps and the other boats cannot understand why anyone bothers with a generator when solar is so much easier, quieter and more reliable.
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Old 11-08-2013, 01:58   #30
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Re: 12v system for everything?

One catch with the Invertors, Dont buy a Modified Sine Invertor, You cant use TV's and some other Stuff on them,
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