How do I connect my new inverter

[a64pilot]

To further drift the topic, yes you can run a 530W dehumidifier off of an inverter, but as that is pretty much a 24/7 load, you would have to have a HUGE bank, and rather large charging source to keep it up.

Check my math please 530 div by 13 = 41, so with 100% efficiency 530W takes 41 amps at 13V?
times 24 hours is roughly 980, so it would take 980 AH out of a battery bank to run that dehumidifier for 24 hours assuming it ran continously

[ramblinrod]

Originally Posted by Dockhead

AC is a whole lot more efficient than DC, and in every case, IF the AC is at 110 volts and the DC is at 12

That's what I meant, but I didn't express is very well.

The point is that you need much heavier cabling to carry the same amount of power over 12v DC, than you do at 110v AC, so logically you should try to locate the inverter so that the DC cables are shorter rather than longer, and send the power to the consumer, to the extent possible, via the much more efficient 110v AC route.

Efficiency is a measure of the ratio of energy consumed vs that actually used for an intended purpose, (the balance being effectively "lost", in some other form).

All electrical current whether it be AC or DC is 100% efficient.

It is the transmission lines and load connected that have some "efficiency" factor.

Ramblin Rod
Marine Service Provider
About Sheen Marine

[ramblinrod]

Originally Posted by Ribbit

I was looking at the Cobra inverters, what's the build quality like?


I was wondering about maybe getting a 2.5kw one. It will run a small steam cleaner ok (plenty of spare capacity for that), and wondering if it will also run a 530 watt dehumidifier.

Some modified sine wave inverters will run compressor type devices like dehumidifiers (and fridges) with no problems, then others you have no chance with.

I moved a lot of Cobra gear many years ago, and the build quality then was good.

I need to keep on top of molds and spores (they've caused me some major problems - taking lead out of paint is causing a considerable amount of grief since we lost its control effect on molds and spores), so if I can do it with a good modified sine wave inverter, it will be a huge help.

Everything else I'll try and do with 12v chargers to save conversion losses.

For the OP, make sure you heavily overspec the DC supply cables to keep everything running nice and cool (helps reliability and long service life). 170 amp DC cable will allow you a lot of leeway for any future reasonable sized inverter. Beyond 170 amp and cable starts getting expensive.

Pls show me 170 A cable?

Hint, there is no such thing.

The current carrying capacity of the cable is dependent on its cross sectional area (gauge) and length.

[Ribbit]

Originally Posted by thomm225

Seems okay. I paid $30.00 for it so i didn't examine it too closely.

Seems to work fine.....

Much appreciated.

[Ribbit]

Originally Posted by ramblinrod

Pls show me 170 A cable?

Hint, there is no such thing.

The current carrying capacity of the cable is dependent on its cross sectional area (gauge) and length.

Hint: "BLACK RED 16mm 170AMP Copper Welding flexible Battery Earth Marine Starter Cable"

BLACK RED 16mm 170AMP Copper Welding flexible Battery Earth Marine Starter Cable | eBay

Loads of it over here . . . . . . (1,373 results for 170 amp battery cable)

Sorry about the thread drift by the way, but the chance to ask someone with a Cobra inverter about them, couldn't be missed.

a64pilot

To further drift the topic, yes you can run a 530W dehumidifier off of an inverter, but as that is pretty much a 24/7 load, you would have to have a HUGE bank, and rather large charging source to keep it up.

Your numbers are in line with what I reckoned.

I'm looking at a 660 to 880 ah bank, depending what I can fit in, but only running the dehumidifier for about 2 x 2 hour periods a day (couple of hours early afternoon while cooking lunch, couple of hours early evening while cooking supper), to keep humidity well under control and help keep the interior aired, dry, and mold and spore free. That will also knock out a gallon of distilled water approx. from a 50 pint dehumidifier.

Mainly just countering the water content from cooking fuel, pressure cooker, etc.

I'm planning on 400 to 600 watts of solar panel input (have to see what 2 or 3 panel arrangement looks available for a decent deal). I will run the engine for a decent period most days too, for a while at least, do some frequent oil and filter changes, just to make sure everything is ship shape with it, then I'll keep a very close eye on the voltmeter. If it goes down too fast, I'll cut back to 2 x 1.5 hour sessions, or 2 x 1 hour sessions.

Don't worry I won't let the battery bank get low (my red line has always been 12.2v).

[rwidman]

Originally Posted by AFKASAP

Hi there!

I just received my new Victron Inverter 350 wat.

I would like some advice about how to connect it to my 12v system. It comes with a red and black cable already wired into the unit.

How should I connect it into my system and should I put it on a switch so I can turn it on and off?

Did it come with instructions? Do you understand the instructions? If not, hire a pro. Nobody can explain everything you need to know on a web forum (although some will try).

Electricity and water can be a lethal combination so this needs to be done right and according to ABYC standards.

[ramblinrod]

Originally Posted by Ribbit

Hint: "BLACK RED 16mm 170AMP Copper Welding flexible Battery Earth Marine Starter Cable"

BLACK RED 16mm 170AMP Copper Welding flexible Battery Earth Marine Starter Cable | eBay

Loads of it over here . . . . . . (1,373 results for 170 amp battery cable)

I stand corrected, there is such a thing as called "170 Amp" cable in the UK, with which this Canuck was not previously familiar.

Sorry for the incorrect error accusation, and thanks for the lesson.

But 25mm^2 cable for a 300W inverter? Seriously?

[Dockhead]

Originally Posted by ramblinrod

Ummm, don't think so.

While 12Vdc won't electrocute you, improperly handled, it will certainly burn your boat to the waterline.

A 350 W inverter will draw over 30 Amps and most (spare) DC breakers (if any) in a DC distribution panel are 15 Amps. So if one connected any load greater than about 180W it would trip the breaker (hopefully).

Additionally, laptops may require some other voltage, so a cigarette lighter adapter may not work, and may damage the laptop. (One also has to be careful about polarity.)

The correct answer is, if you are not familiar with ABYC standards, (which you aren't or you wouldn't be asking these questions), you should either acquaint yourself intimately, or hire a marine electrical professional.

(Ask to see their certification AND liability insurance, and if they don't have it, send them packing, they're just some joker who is willing to experiment on your boat for your money.)

Some answers you get from internet forums are wrong, and if you don't already know how to do it correctly, you don't know which ones they are.

Ramblin Rod
Marine Service Provider
Certified Raymarine Installer
About Sheen Marine

So to which part of my post does "umm, don't think so" apply specifically, or is that just generally a statement that one should never install any electrical equipment oneself, and always hire a pro?

Hiring professionals can be a good idea in many situations, but you had better know enough about all of your systems, and the principles upon which they work, to recognize whether you are getting good work or not.

In my experience, the average skill level of professional marine electricians is particularly poor. About half of them -- in my experience -- are not capable of doing the work as well as I can do it myself. You have to look long and hard to find a really good one, and qualifications and other papers are not a reliable guide.

[rwidman]

Originally Posted by ramblinrod

Pls show me 170 A cable?

Hint, there is no such thing.

The current carrying capacity of the cable is dependent on its cross sectional area (gauge) and length.

The current capacity of a cable depends on it's gauge. Length has nothing to do with current capacity.

[Dockhead]

Originally Posted by ramblinrod

I stand corrected, there is such a thing as called "170 Amp" cable in the UK, with which this Canuck was not previously familiar.

Sorry for the incorrect error accusation, and thanks for the lesson.

But 25mm^2 cable for a 300W inverter? Seriously?

I actually agree that there is no such thing as an "x amp" size cable, no matter how some cabling may be advertised.

To know the right cable size, you need to know three things:

1. amps you want to transmit
2. length of the cables over which you will be transmitting these amps
3. acceptable voltage drop for your usage

Here is a good calculator: DC Cable Sizing Tool - Wire Size Calculator - MM2 & AWG - solar-wind.co.uk

Note that voltage drop is not the only effect of transmitting over cables -- you also lose power through heating of the cabling. This effect is proportional to the voltage drop.

It is generally more efficient, and certainly less expensive, to transmit the power using the AC side, rather than the DC side, because it is easier and cheaper to size the cabling to minimize the power loss over your cable run.

I dislike 12v in general because it requires expensive and bulky cabling to transmit even modest amounts of power over any distance with it, with any efficiency. Much prefer 24v systems.

[Dockhead]

Originally Posted by rwidman

The current capacity of a cable depends on it's gauge. Length has nothing to do with current capacity.

That's not exactly true. It's true concerning heating of the cable, but not concerning voltage drop and power loss, and those are primary design values. Voltage drop and power loss increases proportionately with the length of a cable, so you need bigger and bigger cables, for longer cable runs, to transmit the same number of amps and stay within some acceptable limit of voltage drop.


To rephrase more exactly what was said earlier:

"The current capacity of a cable, for constant voltage drop, depends on its length as well as the gauge of the cable."

To give a concrete example:

If you want to transmit 30 amps over a 1 meter long cable, and you want to stay within a 1% maximum voltage drop, you need a 6mm square cable (10AWG).

If you want to transmit it over 10 meters, you need a 50mm square cable, or 0 AWG.

So the 10AWG cable has a capacity of 30 amps over 1 meter at 1% voltage loss. Over 10 meters, it has a capacity of 3 amps. If you can accept more voltage drop, then the capacities increase in both cases.

[ramblinrod]

Originally Posted by Dockhead

So to which part of my post does "umm, don't think so" apply specifically...

Well, I thought I covered it with considerable detail but, here goes...

1. Your post, "If you want it permanently installed, AND assuming you have a free breaker on your DC panel, then just connect it to that..."

Ummm, I don't think so. As stated in my response, if the DC panel has a spare breaker, it is most likely 15 A, which will be totally inadequate for a 350W inverter.

2. Your post, "That is because DC at low voltage is less efficient than AC."

Ummm, I don't think so. As stated in my response, electricity is a form of energy. Whether it be AC or DC it is 100% efficient. The transmission line and load may have an efficiency factor, the electricity itself does not.

3. Your post, "Then install an AC socket somewhere, and run three-conductor, sheathed cabling from the inverter to there."

Ummm, I don't think so.

a) The inverter in question is not likely designed to be connected to external AC wiring.

b) If it is, and the outlet is in a galley, head area, engine compartment, or anywhere it could get splashed, it must be a GFCI.

4. Your post, "Follow ABYC standards: American Boat & Yacht Council Standards for Boats E-11 | Ancor (link)"

Ummm, I don't think so. That excerpt only covers cabling. To install an inverter to ABYC standards, one must consider E10 - Storage Batteries (8 pages), E11 - AC and DC Electrical Systems on Boats (96 pages) and A31 - Inverters and Chargers (15 pages). The little excerpt on the Ancor site is outdated and a very small portion of the applicable relevant standards.

5. Your new post, "Hiring professionals can be a good idea in many situations, but you had better know enough about all of your systems, and the principles upon which they work, to recognize whether you are getting good work or not."

Ummm, I don't think so. It is not a requirement to be as knowledgable or nearly as knowledgable as a professional of any trade or profession, it isn't even practical. And if you were, then why hire a professional?

6. Your new post,"In my experience, the average skill level of professional marine electricians is particularly poor."

I'm sorry you have had a bad experience. Are you sure these were really certified professionals? If they were, you should have contacted the certifying agency, filed a complaint, and they would have been called up. In all likelihood, they weren't certified professionals at all, rather just someone who agreed to take your money.

7. Your new post, "About half of them -- in my experience -- are not capable of doing the work as well as I can do it myself."

Again, I'm sorry your have had such a poor experience. While you could be an unusually capable DIYer, but I suspect you are referring to poorly educated and paid general labourers, and not certified marine professionals.

Notwithstanding, as there are literally millions of different products that have been installed on boats, it is not possible for any one marine professional to be knowledgeable of every single one. Whereas the boat owner, may have used a specific marine product daily, and poured over the manuals for hours on end, year after year, for 20 years. They will most certainly may be more knowledgable on that specific product than the average marine professional. However, the general knowledge of the marine professional, should enable them to solve the problem the highly knowledgable owner (of that specific product) can't.


I'll be the first to admit that I don't know everything about marine electrical systems, and some owners may know more about their specific systems than I, after all, they may have been intimately familiar with it for 20 years, whereas my expose to that specific model may be very limited. For

8. Your new post, "You have to look long and hard to find a really good one, and qualifications and other papers are not a reliable guide.

Any certified marine professional, has to have undergone fairly extensive training, and passed an extensive certification test, with a minimum grade (typically 80% or higher). This is not a fluffy test. Few pass it first attempt, after extensive practical experience and then specific training for the exam. Again, as I've said on this forum many times, when you hoire a marine professional, ask who they are certified by. It should be a well known agency or manufacturer. Before you let them on your boat, ask to see their certificate. If they aren't carrying it in their wallet 24/7, they most likely aren't certified at all, send them packing.
[/QUOTE]

[Island Time O25]

Here is how I installed mine. And some questions to the knowledgeable members to compare to the adivice given by my marine pro-buddy.

1. Last spring installed el cheapo ($100 on sale) 2000W (peak 3000W) converter from HF (I know, I know but anything much above that price would be a non-starter for me)

2. Got installation advise from a marine pro buddy of mine (with 40+ years of very extensive and wide marine experience).

3. Used 00 size cables with the shortest possible run to the battery, app. 4'.

4. Installed directly to the battery without breakers as these are supposedly internal on the inverter (not 100% sure on that).

5. Use it intermittently and turn it off each time I'm not using it and certainly when off the boat, mostly just some TV watching, knife sharpener, some power tools, solder iron, etc. as most of my other stuff is 12v anyway, this was installed more for the guests and their chargers or an occasional 110v power tool. Ironically, subsequent to installation, at a yard sale, I came across a set of brand new camping/RV kitchen appliances all 12v - coffee maker, grinder, blender, chopper, etc, so now that inverter will be used even less. ))

Should I place a breaker (most likely regular Guest battery switch) near the battery side? Do the 00 cables drain any juice off of the battery even when inverter is switched off? If not Guest battery type switch what size breaker would be appropriate if necessary? My buddy says none is needed if the cables are so oversized.

Any other concerns, issues I should be aware of? Thanks.

[Stufft]

170A cables seems a bit extreme for a 300W inverter. I always thought the '300W' stated was the output power, therefore if the inverter is a 110V system it would be 300W/110V=less than 3A

[StuM]

Originally Posted by Stufft

170A cables seems a bit extreme for a 300W inverter. I always thought the '300W' stated was the output power, therefore if the inverter is a 110V system it would be 300W/110V=less than 3A

On the 12V DC side where those cables will be 300W =~ 25A. And with a peak output of 600W, that is 50A.