Harbor Freight Inverter

Hello!
I have a 1998 Mainship Pilot 30 with no AC electric except shore power. We keep her in front of our house on a freshwater lake with very little likelihood of ever seeing salt on our watch. We have a reverse cycle air, two burner cooktop, and water heater (with an exchanger that uses engine heat) that are all AC. I would like to add an inverter but the cost of marine inverters are a little out off reach for now. Has anyone used a Harbor Freight inverter in their boat? (and yes, I am usually the one that nay-says non marine parts in boats) Any opinions?

Thanks in advance…

A non marine inverter to run a TV or a blender is one thing. Wiring an inverter into the boat’s system is another. You should be well versed on fresh water electrocution first.

tiltrider1 said:

A non marine inverter to run a TV or a blender is one thing. Wiring an inverter into the boat’s system is another. You should be well versed on fresh water electrocution first.

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Good thought!

It is never possible to remove the non marine equipment after the problem and before the insurance investigation if you want to make a claim.

To do what? Just a small inverter to run a few things, or a full inverter charger to run the entire AC loads off the AC Panel?

Most inverters these days are made for RV and off grid solar matkets, not specifically marine which is a relatively small market. So no fear of marine upcharge (which I believe to be over stated, but another topic)

PSW inverters from GoPower and Wagan are reasonably priced and are rated to provide 100% of their states output continuously for 24 hours, an impressive test. Avoid Renogy products for anything as they have zero customer support and are difficult to work with if a return is needed

Finally, I'd add that there is considerable expense when installing an inverter the first time due to cabling, fittings, circuit protection, meter/control, etc. Costs as much to install a cheap Harbor Freight as it does a top quality Magnum, Victron, etc.

Good luck.

Peter

mvweebles said:

Finally, I'd add that there is considerable expense when installing an inverter the first time due to cabling, fittings, circuit protection, meter/control, etc. Costs as much to install a cheap Harbor Freight as it does a top quality Magnum, Victron, etc.

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I'll pile on to Peter's good points. When you start using the inverter you're likely going to quickly find that your storage (batteries) and OEM generator are not up to the task of providing all that power that you thought you'd get from the inverter.

Running the air, stove or water heater off an inverter is likely a non-starter without some serious spend.

Trying to be helpful here. I see people put in new 1500+ w inverters without considering the power needs and it usually doesn't end well. If you're just looking to power a laptop or small TV a high quality 300w unit is cheap to buy and cheap to properly wire to one or two dedicated receptacles, and won't run your batteries flat in an hour.

All good points to ponder…

No onboard genset, it probably would cost what I paid for the boat to install


Thus the inverter question in the first place. 3000 watt Chineesium inverter is $350. I am a talented land electrician, and mechanic. I will have the aid of a first rate professional marine mechanic. I was considering wiring it to the shore power circuit. Would probably not need the water heater portion as no long anchorages are planned and the engine heat gets it HOT. Mostly I will need short runs on the stove top and my CPAP machine. Judicious power management should handle that. HOWEVER, the insurance question does give pause…

BTW… Thanks for the input!!!

A. must have healthy batteries to support your inverter.
B. Check the capacity of engine alternator
C. 1800 to 2000 watt inverter (maybe less if you promise not to use the
microwave oven on the inverter.)
D. An extra amp meter located in the area of the greatest draw on the inverter
so you overload the turn to boat off.
E. Dont plan running the reverse cycle A/C on the inverter.
F. I doubt if you will be able to use the the electric stove, away from the dock

3000 watts is 300 amps DC current at 10v. Start sizing the wiring requirements for that, and the battery bank you need to supply that current.

Most folks who want a cheap easy solution get a portable gas generator and run it on the swim platform or in the dinghy. Or in my parts they run them in the bushes next to the dock with a long cord.

Read your insurance policy or call them.

Never had a policy that said all appliances needed to be marine grade.

The wiring should meet ABYC for a few reasons if you care... even then, policies cover you for a lot of things they probably wish they didn't have to.

Fr8dog61 said:

All good points to ponder…

No onboard genset, it probably would cost what I paid for the boat to install


Thus the inverter question in the first place. 3000 watt Chineesium inverter is $350. I am a talented land electrician, and mechanic. I will have the aid of a first rate professional marine mechanic. I was considering wiring it to the shore power circuit. Would probably not need the water heater portion as no long anchorages are planned and the engine heat gets it HOT. Mostly I will need short runs on the stove top and my CPAP machine. Judicious power management should handle that. HOWEVER, the insurance question does give pause…

BTW… Thanks for the input!!!

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I went the exact same route as you are thinking about taking and bought a $300 Chinese 3kw sinewave inverter. First, I had it wired into my ships AC system to power the whole boat. No matter what I did, it wouldn't correctly feed the circuits. Even with the breakers off, it would backfeed and light the indicators on the breakers. The battery charger would come on with the breaker off while the inverter was on. I gave up trying to feed the ships panel with the inverter and simply ran a line directly to a designated receptacle for the microwave. It does ok but it's is definitely NOT a sinewave inverter. The microwave sounds like it's being smacked with a hammer 60 times per second and after running it for 3 minutes, it get's hot and shuts off (the microwave while on inverter power). I'm going to pull the POS inverter out before we head South this fall and replace it with a true sinewave Samlex 2000W.
If you want my 3kW POS inverter, you can have it for free. That's how serious I am when I ask you to not waste your time & money on a cheap inverter and to go with a better quality sinewave unit. You'll be much happier.

In the past I have purchased some tools from Harbor Freight that I considered one time use tools. For the most part they sell a lot of cheaply made Chinese quality stuff. Any inverter they sell will not be the quality I would buy for a boat.

Bill V said:

In the past I have purchased some tools from Harbor Freight that I considered one time use tools. For the most part they sell a lot of cheaply made Chinese quality stuff. Any inverter they sell will not be the quality I would buy for a boat.

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Agreed, very true. Harbor Freight is the place to go if you need a dolly or such, not for electronics.

I'd just like to reinforce a point made earlier. For many low draw things a point-of-use inverter may be fine. Or, maybe a one-circuit/one-outlet solution.

A good number of people use a point-of-use inverter for their refrigerator vs buying a marine unit.

I have a kiosk touchscreen attached to a mini-PC to run OpenCPN on the flybridge. The screen is 12v. The PC runs off of a point of use inverter that gets power off of its own 12v circuit right there.

I do have a proper 2000w marine inverter and house bank, and proper marine 50A genset. And, for my style of boating, I wouldn't be without them. But a lot of folks don't need or want that.

And, even with that, sometimes people want something to be 12v. I wanted that plotter to be off the 12v circuit so it works even without the genset or inverter. I do have a simrad up there, too. But in the event I lose 120v, I'd like to keep both of the plotters running as it gives me my preferred presentation of navigation information.

Many additional thoughts here.

First, don't be seduced by 3kw number. Without sufficient battery capacity, you can't draw that without issues. And most inverters have surge capacity of 50%-100% over. You really should size cables to surge capacity, which would be massive at that power. There's a good chance a higher quality 1kw PSW inverter will perform much better snd handle your loads much better than a PoS 3kw inverter, even if it claims PSW.

Second, cheap inverters often include cables but they are woefully undersized at the higher power levels. Do NOT assume that the cables included are sufficient.

Third, when cabling, use something like the BSS chart attached. Since you're a seasoned electrician, you know it's measured as a round trip meaning if your inverter is 10 feet of cables from battery connection, you size for 20 foot circuit.

Fourth, you need to size for lower end of voltage drop (3%). There are two places where you will experience voltage drop. Cables (e.g. 3%); and at the battery posts which is not easily calculated as it varies by battery type (FLA drop a lot) and size of bank.

Fifth, if your plan is go wire into your main panel, some sort of transfer switch is needed. BSS makes a barrel switch that is made for thr purpose.

Finally, it's tempting to purchase cheap Chinese components instead of Blue Sea. Don't do it. Bad place to save a few bucks.

https://www.hodgesmarine.com/blu900...TxY67d-PR_BW7ftxqUyTSSygNVQlgOegaAjaBEALw_wcB

3000w is a lot of power. Managing it requires some serious components. Inverter may be cheap, everything else isn't.

Peter

Fresh water boat and a non-marine inverter or inverter/charger can be a deadly combination As a professional matine electrician; I would not do this job.

I guess I'd like to explain some of the key concerns with non-marine inverter-chargers so that this doesn't seem like a religious issue when it is a real, physical one. And also so that one can reason about it vs treating it as superstition, which it is not.

When passing through shore power, a proper (marine) inverter should maintain neutral and ground entirely separately through the inverter (the bonding between the two is on shore), but the inverter should bond them together when it is inverting and is the source of the AC. So the inverter's transfer switch needs to make and break this bond.

Many non-marine inverters don't do this. Some even do whacky things like form the AC wave by driving both hot and neutral.
This is a real problem because it disables the safety grounding conductor and can let any metal connected to it or the chassis become hot or a current-carrying return path. That includes parts of the boat connected to the water, which means one can put current into the water, among other things.

Another problem that comes up involves the grounding. An inverter has both 12v and 120v in it. For the same amount of work, the current is 10x higher at 12v than 120v, so the wire needs to be much thicker for 12v. Unless the inverter is properly grounded, should something go wrong, DC currents can travel through thin 120v wiring. That is a big fire hazard that often is hard to get right when installing a non-marine inverter.

And, of course, non-marine devices may be more likely to corrode or otherwise fail in the moist, salty, vibration and shock-filled environment of a boat, which is bad -- and makes the problems above worse.

If the inverter is point-of use, without a transfer switch, and in no way connected to the boat's normal AC system, the risks go down a lot. Then the 120v load is just another form of work being done by the boat's DC system, not connecting to, or altering, or reconfiguring, or loading, the boat's or shore's AC wiring in any way. It is basically like a car inverter running a laptop from a cigarette lighter.

I don't want to advocate for anything here. But I do think that one can draw some distinction between a supply and distribution system and a simple load connected to one. Doing that may, or may not, lead one to think about some things differently than if that distinction is not made.

Amy time you want to have a permanent install for any heating appliances (hot water, kettle, microwave, AC etc) you really don't want to be doing that off 12v and will need sizable cabling and battery bank.

Wth respect, if these are out of the budget then a cheap portable genset is the best solution. It will work the first time, no installation costs, you won't burn you boat down nor electrocute anyone.

I am going to repeat what I said in post #2. Before you wire in a non marine inverter, Google fresh water electrocution. You do not want to be on the wrong side of a wrongful death lawsuit.

tiltrider1 said:

I am going to repeat what I said in post #2. Before you wire in a non marine inverter, Google fresh water electrocution. You do not want to be on the wrong side of a wrongful death lawsuit.

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Any further xomment on difference between a marine inverter and a non-marine inverter? Recommendations?

mvweebles said:

Any further xomment on difference between a marine inverter and a non-marine inverter? Recommendations?

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Many residential inverter chargers simply will not work when plugged into a RCD equipped shore power outlet because as gkesden noted the unswitched Safety Earth-Neutral bridge will be recognised by the shore power and the shore power RCD will disconnect ie no shore power feed nor battery charging.

From a residential inverter charge manufacturer here in Australia:

"The inverters are not electrical appliances and they cannot sit downstream of an RCD. Any RCD protection must be after the inverter on the AC OUTPUT or load. Yes, the Neutral and Earth are bridged inside the inverter, this is a physical constant bridge."

I haven't been awake for an hour and already I've learned something- RCD means Residential Current Device, some sort of GFCI-like grounding that has been required on all households in Australia since 1991. 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.

It does nor sound like the OP is interested in an inverter-charger, but rather just a plain inverter. What design attributes or certifications (e.g. UL) would be listed as bring "Marine Grade?" How would it differ from a quality inverter made for RV or off-grid solar?

BTW - one further generic attribute I can think of for an inverter larger than 1000w is ability to hard-wire AC output vs just having a gang of 15a outlets.

Peter.

What if you bought one of those little Honda ( or similar ) portable generator, and just ran stuff directly off that, seperately from your boats electrical system ? You could also you that to charge your boat's battery bank to make your 12 volt systems more robust. It would be a little more expensive but would provided added utility of a generator you could use for camping, home power outage, at your buddy's hunting cabin, etc.

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

They dont have shore AC anywhere inside of them.

They can, and likely do, bridge their /output/ neutral and ground all day long -- without impacting the boat's normal AC system or shore power, from which they are 100% unconnected and independent.

They can't pop ELCIs, GFCIs, or other RCDs. They are 12v loads w.r.t. the boat's wiring with no interaction with shore power on shore or aboard.

Jeff F said:

3000 watts is 300 amps DC current at 10v. Start sizing the wiring requirements for that, and the battery bank you need to supply that current.

Most folks who want a cheap easy solution get a portable gas generator and run it on the swim platform or in the dinghy. Or in my parts they run them in the bushes next to the dock with a long cord.

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Good point! I've seen several portable non-marine generators used on boats. To me, that's a smarter solution than trying to use a cheap, non-marine inverter. In one case, they ran it all night on the cabin top. I assume it was for air conditioning.

As for what I'd consider a marine rated inverter....something that is listed as UL 458 with Marine Supplement, which means it passes the testing for inverters as well as extra testing for them w.r.t. marine environments.

Is your boat diesel? If so, the engine 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.

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.

gkesden said:

As for what I'd consider a marine rated inverter....something that is listed as UL 458 with Marine Supplement, which means it passes the testing for inverters as well as extra testing for them w.r.t. marine environments.

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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)

This GoPower 2000 PSW inverter is UL 458 certified. About $600. I know its more than a $200 cheap inverter, but likely rock solid. Given the cost of install, differential in price may be justified.

https://gpelectric.com/products/2000-watt-industrial-pure-sine-wave-inverter/

For your CPAP if it uses a "power brick" look at the label on the brick. If you're lucky the output from the brick is 12 volts DC. If so it's a matter of finding the correct male plug, a bit of cabling and you can run it straight from your boat's DC. Pay attention to polarity.

If the plug is near impossible to find buy a used brick for your machine on eBay and cut the plug off.

Also if your CPAP has a humidifier tank with heater that can be removed to connect the hose direct to the air pump you will reduce the power required considerably. It's the tank heater that draws most of the current. And you won't need to carry distilled water. This was suggested by my Dr who says the humidity on a boat is high enough to not require the humidifier. I have had no problems leaving the tank and distilled water ashore.