Harbor Freight Inverter

[Solly]

Get a small gas portable generator with a 30 amp plug. Plug your shore power cord right into it. Might not run the AC and stove at the same time.
See if your CPAP machine has a 12v adapter available. We plug my wife's into a cigarette plug.

 

[backinblue]

Another option: For your CPAP and other low wattage use you might consider a small portable power station. Contains batteries and inverter in one unit. Get one using LiFePo4 cells for safety. Might also come in handy during power outages onshore.

I considered buying one of those but the output power for AC was very low. I'm sure there are bigger and more expensive ones.

 

[backinblue]

Is your boat diesel? If so, thebwngine room is probably not ignition protected.

Before adding a gasoline generator I'd have a plan w.r.t. storing as much fuel as you expect to need.

People do solve these problems...but down in the bilge, or laz, or engine room, etc, is probably not the right answer.

For the small portable gas units being suggested, I think the assumption is they will remain outside, like on a swim platform for example.

 

[STB]

I was not aware of the various UL certs. Here is an article from a small inverter manufacturer describing. My guess is few manufacturers will bother with UL testing.

https://www.sigineer.com/news/difference-ul458-ul-1741-power-inverters/

My strong hunch is there is much more risk of poor install with undersized cabling than a non-UL inverter as long as you go with a decent brand of inverter (rules out Harbor Freight)

The challenge with unlisted devices is that it is really hard to know what you are getting.

If looking to purchase an unlisted device for other than point-of-use, my suggestion would be to use caution and check those things that you can check, e.g. grounding and bonding and general construction character and quality.

I view these things as choices. Personally, I wouldn't do it for an inverter. I see a lot of risk.

But, I have for other things. It certainly isn't the case that everything in my boat is marine rated or marketed.

 

[kthoennes]

Just a note....point of use inverters do not have a pass through or transfer switch...

Gkesden and others know way more than I ever will about electricity so I'm reluctant to say anything, but from my last project I agree with you about inverters for point of use but not whole-house. For my last project I did get an inverter with a transfer switch, but my project was just point of use. Well, three points of use in my case, but still a very light load. With lots of very helpful advice here on the forum I installed one of these for a new refrigerator:

https://www.donrowe.com/cooper-buss...mMMoUNXY5nIp9rKTsKyNry6-OiS9FalxoCcpsQAvD_BwE

(And the advice about pure sign wave was spot on, it doesn't hum loudly.) The new fridge is amazingly efficient though, just pulls 25 watts when it's running, so that inverter is way beyond what's needed, but the price for the inverter was relatively low so I figured I'd some overkill wouldn't hurt. I have it rigged to just run three things -- (1) the fridge when we're off shore power, (2) it also powers a newly installed USB receptacle near a shelf behind the settee as a little charging area for phones and tablets and game consoles so I could get the electronic gadget and charging mess off the tables and galley counter. And (3) it runs the small cabinet fan to ventilate the fridge cabinet -- that's all. Maybe 30watts max, not counting the efficiency loss of the inverter itself. Our boat does have a genset but we really like it quiet when we're on the hook and that fridge and charging station is such a small load the existing bank covers it easily through the inverter.

https://www.amazon.com/BESTTEN-Rece...ocphy=9020396&hvtargid=pla-319132249602&psc=1

 

[STB]

Hey Kthoennes,

Glad your refridge project worked out! Congrats!

One can certainly do, as you did, and use an inverter with a transfer switch point-of-use. And, it certainly can be perfectly fine and safe.

But, we now have shore power and battery power in the same box, input and output AC lines that need to be connected and disconnected, and a G-N bond that needs to be made and broken. And, have to make sure that the chassis has proper grounding so it can carry DC current back to the battery over thick battery wires not thinner AC wires. What concerns me about these things is that the inverter can seem to work, but generate a safety problem, even if they are wrong.

I might be able to think up other potential wrinkles, too.

So, in my own personal case, I feel really comfortable suggesting that point-of-use inverters with no transfer switch are just DC loads and can be treated like other DC loads.

But, once there is shore AC and boat DC in the same box and/or a transfer switch involved I, personally, can't think of it as a load any more. I think of it as part of the source and distribution system. And that means I start asking the other questions I was asking, and in my own personal case, buy a listed unit where these things have been comprehensive asked, answered, and tested in a systematic and documented way.

In a dry environment, point of use in the cabin, I can see one using a UL 458 unit without the marine supplement. It should still get the bonding and grounding right, etc. Butbtjosebhwlere who call that a slippery slope are probably very right.

 

[kthoennes]

Even with my strictly-amateur knowledge of electricity I share your sense of caution with multiple sources in the same box. In my case I just ran the previous refrigerator DC wires, and the previous AC refrigerator wires, into the DC and AC inputs into the (transfer-switched) inverter. Both of those sources are also switched on the boat's power panel. Theoretically I could leave both switches on all the time now and let the transfer switch in the inverter handle the jumping back and forth, but just as a matter of habit we never have. Before that inverter install I'd always turn off fridge/AC when when we were away from the dock, and turn off fridge/DC when we were on shore power -- and I still do that now. I got into that habit by my father's suggestion so we don't kill the batteries running the fridge if the marina power ever goes down while we're away, and we also don't keep perishable food in there if we're ever gone for multiple days.

 

[STB]

Even with my strictly-amateur knowledge of electricity I share your sense of caution with multiple sources in the same box. In my case I just ran the previous refrigerator DC wires, and the previous AC refrigerator wires, into the DC and AC inputs into the (transfer-switched) inverter. Both of those sources are also switched on the boat's power panel. Theoretically I could leave both switches on all the time now and let the transfer switch in the inverter handle the jumping back and forth, but just as a matter of habit we never have. Before that inverter install I'd always turn off fridge/AC when when we were away from the dock, and turn off fridge/DC when we were on shore power -- and I still do that now. I got into that habit by my father's suggestion so we don't kill the batteries running the fridge if the marina power ever goes down while we're away, and we also don't keep perishable food in there if we're ever gone for multiple days.

One question I'd ask about your installation, and I ask because I dont know the installation details to know the answer, is this: Should there be a failure and the red DC battery wire touches the metal case (from the inside), what sequence of events follows w.r.t. the current path and over current protection?

 

[OldDan1943]

and shall we throw the fuel cell into the mix?

 

[GoneDiving]

In the US, this type of ground fault protection is only required when an outlet is near a water source such as a sink or bathtub.

Peter.

Do US marinas have a GFCI type devices fitted? Every marina outlet here does.

 

[STB]

Do US marinas have a GFCI type devices fitted? Every marina outlet here does.

Newer marinas do have RCDs. And, newer boats have ELCIs. And, boats of modest age have GFCI outlets near wqter, in wet locations, and outdoors.

As a matter ofnoraxtixe, unless a marinabhere has been very recently built or heavily renovated, it doesn't have any type of RCD at the pedestal.

This actually trips up occasional cruisers because their boats are fine at home dock, and many docks, then they hit a new pedestal with RCD somewhere and their leaks or inverter neutral configuration pop it.

 

[GoneDiving]

Newer marinas do have RCDs. And, newer boats have ELCIs. And, boats of modest age have GFCI outlets near wqter, in wet locations, and outdoors.

As a matter ofnoraxtixe, unless a marinabhere has been very recently built or heavily renovated, it doesn't have any type of RCD at the pedestal.

This actually trips up occasional cruisers because their boats are fine at home dock, and many docks, then they hit a new pedestal with RCD somewhere and their leaks or inverter neutral configuration pop it.

It obviously works and I'm no electrician but that sounds terrifying to me both in terms of potential electrolysis to my boat life altering accidents.

RCD type fittings are designed to identify serious faults and to not have them or remove them to hide the faults seems crazy. I've had RCDs identify faulty appliances (toasters and the like) even well away from wet areas.

Rant off ?. ?

 

[CharlieJ]

The National Electrical Code (NEC), Chapter 555, started requiring Ground Fault for Protection of Equipment (GFPE) devices, also known as residual current devices (RCDs), and electrical leakage circuit interrupters (ELCIs) in the shore power circuit in 2011.

The NEC is reviewed and updated every three years and placement of the GFPEs in the supply circuit has changed over the years. The 2020 version of the NEC now requires GFPEs with a 30mAAC trip on each shore power pedestal.

To be compliant with the NEC, convenience outlets are not to be used to provide shore power and they are required to have standard 5mAAC trip GFCIs installed.

 

[kthoennes]

One question I'd ask about your installation, and I ask because I dont know the installation details to know the answer, is this: Should there be a failure and the red DC battery wire touches the metal case (from the inside), what sequence of events follows w.r.t. the current path and over current protection?

Plastic case. Ring connectors crimped onto the ends of the DC wires, on screw posts held under nuts and lock washers. All mounted to a piece of starboard which in turn is screwed to a plywood panel in a very large (vented) dead space behind the settee. But aside from all that, it's a surprisingly sophisticated inverter. It has a battery depletion prevention setting, short circuit and ground fault protection shut-offs, and a remote-mountable readout display (which I've mounted on the outside of the fridge cabinet). All for around $150. For that low price I'm waiting for it to fail any moment but it's been a few weeks and it's working well so far. I did not get the battery charger option because since I'm a cautious amateur, I didn't want to deal with any "backflow" (charging) complications or risks that I didn't understand. Here are the specs:

https://wesgarde.com/wp-content/uploads/bus-cbt-ds-10109-true-sine-wave-inverter.pdf

 

[backinblue]

Looks ok to me, so long as you have the battery power, That would be a problem for me so the generator is my option.

 

[Alaskan Sea-Duction]

Been watching this thread. I run the Harbor Freight 3500w inverter, only to run some small stuff, 5cf freezer, 2.5cf freezer, satellite box, wine cooler.

That's it. The inverter is run off a battery bank of 6 golf cart batteries. This bank is a dedicated only for the inverter.

When I run the genny this bank and others are charged by battery chargers. No inverter/charger. Why?

If you wire your boat up to where all boat systems go through a inverter/charger, then what happens when it dies and you are 2-3 days from a marina? Then wait a week for parts all the while you are running up mooring charges! $$$$$

 

[STB]

That inverter is 100% fine for your use in my book. It is UL 458 listed, so it passes all the electrical tests for an inverter.

It just doesn't have the additional rating for a marine environment, e.g. moisture. But, it seems your installation keeps it out of that situation.

Also even the marine listed units are often listed only for certain installation situations e.g. orientation, with drop guard, etc, that some installers may not follow when installing in a convenient dry and protected part of the boat.

So, I think that isn't a marine listed inverter -- but, personally, Id.likely be okay with your installation.

Somehow I thought we were taking about a Harbor Freight unit, which could be that solid, but seems somewhat low probability.

 

[STB]

If you wire your boat up to where all boat systems go through a inverter/charger, then what happens when it dies and you are 2-3 days from a marina?

You flip the bypass switch to use shore power and/or the genset.

 

[Alaskan Sea-Duction]

Yep. Inverter input is wired directly to the battery bank.

You flip the bypass switch to use shore power and/or the genset.

 

[OldDan1943]

I have 4 switches. 1. power to the inverter from the batteries. 2. turn the inverter on and the switches 3 and 4 are to direct the inverter to A. the microwave or B. to the 120vt outlets in the galley. When I use 3 OR 4 it takes them off the A/C moving them to the inverter.

 

[mvweebles]

Been watching this thread. I run the Harbor Freight 3500w inverter, only to run some small stuff, 5cf freezer, 2.5cf freezer, satellite box, wine cooler.

That's it. The inverter is run off a battery bank of 6 golf cart batteries. This bank is a dedicated only for the inverter.

When I run the genny this bank and others are charged by battery chargers. No inverter/charger. Why?

If you wire your boat up to where all boat systems go through a inverter/charger, then what happens when it dies and you are 2-3 days from a marina? Then wait a week for parts all the while you are running up mooring charges! $$$$$

I've had some DOA issues with inverters. But I've never had a quality inverter/charger fail once installed and running. Honestly, I think there's greater chance of failure running two low quality components than a single/combined high quality one. Mark Twain said "put your eggs in one basket......but watch the basket."

I recently installed a new panel with very simple selector switch for inverter (Magnum 3.2kw hybrid inv/charger driven by 700ah lifepo4), generator, or shore power. 800w solar driving the batteries. I totally understand what the OP is doing with his 30 foot Mainship. But larger cruising boats with multiple inverters snd such are a head scratcher for me. When I do stuff like that, I end up being the only person who knows what's going which makes my wife feel disenfranchised. .

Peter

 

[Alaskan Sea-Duction]

I've had some DOA issues with inverters. But I've never had a quality inverter/charger fail once installed and running. Honestly, I think there's greater chance of failure running two low quality components than a single/combined high quality one. Mark Twain said "put your eggs in one basket......but watch the basket."

I recently installed a new panel with very simple selector switch for inverter (Magnum 3.2kw hybrid inv/charger driven by 700ah lifepo4), generator, or shore power. 800w solar driving the batteries. I totally understand what the OP is doing with his 30 foot Mainship. But larger cruising boats with multiple inverters snd such are a head scratcher for me. When I do stuff like that, I end up being the only person who knows what's going which makes my wife feel disenfranchised. .

Peter

Good point. Sometimes the NAPA or other brand works safely just fine.

 

[FF]

"larger cruising boats with multiple inverters snd such are a head scratcher for me. When I do stuff like that, I end up being the only person who knows what's going which makes my wife feel disenfranchised. "

One simple .solution is to have internal sockets powered by either the dock , noisemaker or inverter, and a plug that fits.

As they are inside, std. range plugs & sockets will do fine and they automatically solve the problem of grounding the white wire to the green wire for different power inputs..

Simple enough , no understanding needed to plug the boat into the live socket.

This concept was used in Bluebird motor homes , the sockets and plug were in a clothes closet.

 

[tiltrider1]

Been watching this thread. I run the Harbor Freight 3500w inverter, only to run some small stuff, 5cf freezer, 2.5cf freezer, satellite box, wine cooler.

That's it. The inverter is run off a battery bank of 6 golf cart batteries. This bank is a dedicated only for the inverter.

When I run the genny this bank and others are charged by battery chargers. No inverter/charger. Why?

If you wire your boat up to where all boat systems go through a inverter/charger, then what happens when it dies and you are 2-3 days from a marina? Then wait a week for parts all the while you are running up mooring charges! $$$$$

When I wire a boat for all power to go through the inverter, I also wire in a bypass switch. This allows the inverter to be bypassed should It fail. I also like having a backup charger.

 

[foggysail]

Sure---the inexpensive true sinewave inverters sold at Harbor, Ebay and maybe Amazon are specifically designed and most sold for OFF LINE applications! But one can get them to work IF you make sure your properly wired boat's load center separates the so called grounded conductor (white wire) from the grounding conductor (green wire).

AND DO NOT HAVE THE BOAT'S POWER CABLE PLUGGED INTO A DOCK PEDESTAL because someplace feeding hte dock pedestal has grounding and grounded conductors tied together.

One should be very careful using so called vehicle inverters on boats even with the grounding and grounded separated. If that inverter is tied into the boat's wiring, the so called grounded conductor, again the white wire, that entire circuit is going to electrically change from 0 volts referenced to real ground to 175V and cycle 60 times/second between 0 and 175V.

Chin up!!!! There is still hope!!

Hope comes in the form of an isolation transformer! If the inverter's output is wired to the primary of a 1:1 properly rated 60Hrz isolation transformer, that properly designed transformer's output can then be tied into your boat's electrical circuit. And no, I am not getting into heated online discussions over this unless the person is an electrical engineer who will know and understand the circuitry.

 

[FoxtrotCharlie]

I installed an AIMS 3000w Pure Sinewave inverter three years ago on our boat (or rather had a marine electrician do the install, with proper cable sizes) Not a charger, just a simple inverter. Powered by four 6v Trojan batteries. It powers only three circuits on my breaker panel - refrig (apt size 110), icemaker (also 110) and the 110 outlets circuit. No A/C, water heater ..... Stove is propane. We have a Kohler 9K gen, but when cruising, unless very hot or cold, we don't run the gen - the inverter carries the load very well. Have a switch that covers those three circuits - they can get power from 1, the panel, or 2 the inverter, but never both - fool (me) proof

Just looked up my AIMS - prices have gone way up.

 

[rwidman]

If you can afford a boat, you can afford to do this correctly. Depending on the capacity, a marine grade inverter can be had for $300 or so. Of course, you may need to pay a pro to install it if you don't have the knowledge to do it correctly yourself.

Electricity and water are a bad mix if done incorrectly.

 

[rwidman]

If you can afford a boat, you can afford to do this correctly. Depending on the capacity, a marine grade inverter can be had for $300 or so. Of course, you may need to pay a pro to install it if you don't have the knowledge to do it correctly yourself.

Electricity and water are a bad mix if done incorrectly.

 

[OldDan1943]

All this talk about the sizes of inverters.
Remember, you need enough healthy batteries to support the the inverter and the demands on the inverter.
If you are not careful you will ruin the 120vt equipment (low voltage) you are trying to run on the inverter, draining the batteries to zero and making toast the inverter.
Having an 800 watt inverter and a 1200 watt microwave will not work even if you have 1200 amp battery bank.

 

[Fr8dog61]

Wow… I didn’t mean to spark such controversy! Maybe we should discuss motor oil or anchoring?


KIDDING

Thanks for all the well thought out answers!