Thoughts on inverters

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Capt. Rodbone

Senior Member
Joined
Sep 6, 2020
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172
Location
U.S.
Vessel Name
SV Stella Polaris MV Sea Turtle
Vessel Make
1978 VanDine Gaff rigged schooner, 1978 Grand Banks Classic Trawler
My wife and I are a few hundred miles into the Great Loop.
We don’t have an inverter but are already seeing how nice it would be to have those additional “ creature comforts”. Can any of you offer advice on things like?
Are they all reliable or are there brands to steer clear of?
Do you have a brand you are extremely happy with?
How much space do they require and for you other 42 Classic owners where did you install it?
I suspect they are sized by anticipated draw. Ours is a 42 Classic with the typical AC needs.Ice maker didn’t work when we recently bought her so I removed it but we may decide to add one at some point. Is there a size we need?
Thanks in advance for any thoughts and suggestions.
 
I've been very happy with the Victron Multiplus I installed. It's also my house bank charger in this case, and integrates nicely with the other Victron gear I have on board. It also has an auto transfer switch, so the group of circuits I've sub-paneled to run from the inverter seamlessly transfer to inverter power once shore or generator power is no longer available.

As far as choosing a size, the first step is to figure out what you want to power from the inverter. Then figure out if you have enough battery to power those loads already, or if you'll need battery upgrades to go with the inverter.


The single biggest improvement the inverter brought for us was making coffee without starting the generator in the morning when we're away from shore power.
 
Sounds like you want a full inverter/charger. 2-years ago, I chose Magnum over Victron for a couple reasons. First, the Magnum is more 'analogue' whereas the Victron is more 'bluetooth.' Now, I have several Victron devices and their bluetooth monitoring works fine, but I wanted a more hard-wired experience. Most people would likely chose Victron because of their bluetooth. Second, the Auto-Gen-Start (AGS) on Victron is more complicated, at least for a generator with with pre-heat such as my Northern Lights (this is a dumb reason for me - I doubt I'll ever use AGS but I installed it anyway).

Size - would go with a 3000W unit with at least 50A of charging. No reason to go smaller. Good ones are lot much over $1k these days.

Location: You will want this within a few feet of your battery bank due to cable length.

Expense: Inverter is the cheap part. Cabling, fuses, monitoring, and connection to panel are the expensive parts. I'd guess $1k DIY; double that professionally installed. Plus battery capacity if you need it.

Good luck -

Peter

EDIT - I started to suggest just a simple inverter without charger and adding a couple dedicated 120VAC outlets to use when needed. But given you want to run your fridge, future icemaker, etc, an inverter/charger is your best bet as it will power as much of your panel loads as you want (most folks isolate resistance heater loads such as water heater and electric stove if present). If you think you can live with just a few dedicated outlets to plug-in a coffee maker, microwave, etc, a more simple and economical solution is install an inverter such as THIS ONE. .
 
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The biggest misunderstanding about inverters is the battery bank. If not large enough and the ability to charge it, inverters can be a unicorn.

Thinking you can wake up and brew a pot of coffee with an inverter is possible with a big enough bank of batteries depends. If it's not, and pretty depleted from miscellaneous parasitic loads of fridges, heaters, fans, and all the rest cruiser energy demands...even a pot of coffee will hurt the bank.

An inverter should be designed into your electrical system, not something just added in.
 
I don't feel qualified to offer advice, but I do have some experience to share. We have a 2,000W inverter/100A charger on our 36'er. For us, that's worked out very well.

When traveling daily or every other day, as one would on the loop, the mains recharge the house bank. If we're on the hook for more than about 12 hours, then running the genset for an hour in the morning, and again in the evening, generally keeps the batteries and hot water tank topped off.

We have no problem running intermittent loads like a microwave, coffee maker or toaster on the inverter, although not all at once. Phone chargers and laptop power supplies are no problem, although we'll unplug them when not in use so the inverter will go into standby mode. We've been known to run things like a bread maker or slow cooker underway, with the alternator powering the inverter. Nothing like pulling into the anchorage to the smell of fresh-baked bread!

We don't have a built-in ice maker, but the 120V counter-top model we use works great. We use it whenever we run low, and put the entire batch in the freezer in a zip-lock bag. We have a 12/120V marine fridge so we don't need to run it off the inverter.

One little convenience is that, if running from marina to marina, we never have to reset the clock on the microwave. The inverter automatically kicks in when shore power is removed. Sometimes it's the little things.
 
Good advice above. First decide what you want to power with an inverter, then see if your battery capacity will support it and then figure out how to replace the amp hours that you draw down to power the AC loads.

You can go as simple as a 1,500 watt inverter that powers a couple of outlets in the galley to use to brew coffee, or a much bigger one with a huge lithium battery bank to run the AC all night and a generator to charge it up the next day.

David
 
I've had a Magnum 2800 installed for about 10 years. It's been flawless. The remote control panel is a must as it makes it very easy to enable and disable both charging and inverter functions. I also added the shunt kit to get accurate battery state-of-charge information.

The 2800 watt size has worked well for the coffee pot, toaster and microwave. A 2000 watt inverter probably would have worked just as well.

One thing I had to do was move the hot water heater to a separate circuit so that it was never powered by the inverter. A friend with a boat in charter service has problems with battery life, I think because people leave the ice maker running, which is on the inverter circuits.

I wanted mine installed in the engine room, but the electrician at the yard wouldn't do it, so it was installed in a hanging locker. I'm sure you have more options on your boat. However, because of the large currents involved, being close to the house batteries is the best option.
 
As others have said, adding an inverter isn't a single-item project. Batteries, fuses, wiring, breakers/switches, etc. and there are maximum recommended physical distances involved between batteries, fuses, and inverter. And then there are load factors.

I can tell you what we did, but it won't necessarily be the best solution for you.

First, I looked at our existing battery sources, and physical locations. Our thruster bank is otherwise unused, so seemed like a good source for otherwise semi-wasted batteries. The thruster bank charger was very near the thruster bank. And all that was very near our main AC/DC distribution panel. All good.

Next I looked at loads: freezer and fridge in the galley, fridge on the bridge, icemaker (or another fridge) on the bridge... some low voltage AC lighting systems... plus outlets... some of which control microwave, coffee maker, stereo/TV, etc... and some of which are just wall outlets. All that mostly added up to "big inverter."

So finally I shopped on products, ended up with a Victron MultiPlus inverter/charger, pure since wave 3000W inverter, 70 amp charger. Can say yet whether it's better than other brands. Works. Has an automatic transfer switch. Seems good.

The inverter/charger was relatively inexpensive. The installation, done by ABYC electricians, was a fair bit of coin. I could not have done it myself, partly because of physical details, partly 'cause I dunno enough about how.

After all that, I also replaced the old FLA "starter" batteries in that thruster bank with Lifeline AGMs, a decent increase in bank capacity... and they can take better advantage of the 70A charging.

Mostly our usage is when underway or at anchor but not needing AC/heat, hot water, or the electric stovetop for cooking.

So far, so good.

-Chris
 
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We went with the Victron Quattro 5000 inverter/charger.

Our boat had no inverter when we purchased her used.

We replaced the old Xantrex 12v battery charger (which died right after we purchased the Victron).
As mentioned above, the Victron units have a built in transfer switch, so I will be able to remove the large (old) manual transfer switch as well (that's a project for this Spring).

When looking as something like an inverter, where no one has previously been present, it would be a good idea to survey your entire electrical system, including batteries, bus bars, wiring, alternator/regulator, etc, and not just assume that you can "plug and play" something like an inverter.

We ended up:

  • replacing/upgrading the house battery bank (we went LiFePO4)
  • replacing ALL of the battery wiring
  • replacing ALL of the bus bars (terminal blocks)
  • replacing ALL new circuit protection on the batteries
  • Adding battery monitors w/ bluetooth, etc
We still have to integrate the existing generator to the Victron Quattro as mentioned above, which will be done in the New Year.
Overall, we have been very VERY pleased with the Inverter, and the upgrades we've done.:dance:
 
I forgot to mention a few things.

First, one of the best uses for the inverter turns out to be running the navigation laptops at both the upper and lower helms, and just generally being able to use the appliance while underway in a slow boat. This places more of a load on the alternator than the batteries.

Second, when I bought the inverter/charge I focused a bit too much on max charging current (100A) because I wanted to minimize genset run time. If I had lithium batteries it might be a different story, but with lead-acid technology most of the charging time is spent at lower currents than the initial bulk charge.

Finally, if you buy an inverter/charger, make sure it supports all of the battery technologies you'll ever want to use.
 
We spend a lot of time on the hook and don't like running the generator so we recently upgraded the house bank and inverter/charger. The house batteries are SOK marine LFP and the inverter/charger is the Victron Multiplus 3k. I went with the Victron because it can charge at 120 amps. This minimized the generator run time because the LFP batteries soak up about 110 amps until the SOC is about 98%.
 
I have a Magnum Energy 2,800 watt pure sine wave. Been extremely happy with it. As others have mentioned, battery bank size is important if you plan to use it with the engine off.

I would also say that alternator size and whether it's commercial duty can be equally important. I have a commercial duty 220 amp Leece Neville alternator with a Balmar external regulator to both charge the battery bank and power the inverter. This is a second alternator on my main engine. While many on the forum will use their inverter for light loads or short time heavy loads (microwave or induction cook top), I use mine also for long term heavy loads. The ability for the second alternator to continuously produce high amperage allows me to run the Splendide washing machine in dryer mode for hours while underway. While I could run the generator to power the washing machine, the generator would be poorly loaded. Makes more sense to run it off the inverter while underway.

So my advice is to spend time considering what you might run off the inverter while underway.

Ted
 
psneeld said:
the biggest misunderstanding about inverters is the battery bank. If not large enough and the ability to charge it, inverters can be a unicorn.

Thinking you can wake up and brew a pot of coffee with an inverter is possible with a big enough bank of batteries depends. If it's not, and pretty depleted from miscellaneous parasitic loads of fridges, heaters, fans, and all the rest cruiser energy demands...even a pot of coffee will hurt the bank.

An inverter should be designed into your electrical system, not something just added in.
Click to expand...

^^^^^ this
 
We added a 2000W Pure Sine Wave Magnum Energy with the remote. The Remote is essential for ease of programming and to use its features to the fullest. Remember that something that draws 10 amps at 120VAC will draw 100+ amps at 12 VDC from the battery bank. Stay with a certified marine Inverter/Charger unless you only need a single use type low watt inverter to power a laptop, TV, or something else tiny.

Pros:
Big 100+ amp charger for charging the house bank with the generator. We typically run the gen 1 hour, twice a day and it will bring the bank up above 80% SOC quickly.

With the main engine running while cruising, you can run the microwave much longer for making coffee or whatever.



Cons:
Any more than about 2 minutes with a microwave will draw down the bank voltage to the Low Voltage Cutout voltage.
Big house battery bank required.

Correct installation is at the top end of a typical DIY boaters abilities. It requires electrical knowledge, fabrication of heavy gauge copper cables, fuses, and maybe some re-organization of the existing power panel and shore power circuits. If in doubt, use a professional marine electrician for the install.
Consequences of improper install are high. From tripping out transient dock ground fault protection, out of control underwater metals corrosion, fire, or shock/electrocution hazards.

The bigger the inverter, the higher the standby energy use. Mine uses about 2 amps DC if running unloaded. Those amp-hours add up overnight. A useful feature is the standby mode which waits for a load to get switched on to come to life. This lowers to amp draw to under 1 amp if selected but requires a second or two to respond.
 
I have no complaints about our Xantrex Freedom SW 3012. At this point in history, my reading suggests that Victron has the edge in technology and is likely the smart choice if you are buying today. Looks like the significant majority of recommendations so far point that way.
 
HeadedToTexas said:
I have no complaints about our Xantrex Freedom SW 3012. At this point in history, my reading suggests that Victron has the edge in technology and is likely the smart choice if you are buying today. Looks like the significant majority of recommendations so far point that way.
Click to expand...
Xantrex has been slow to make their chargers Lithium ready. Not sure about this particular model, but worth noting for OP that if he decides to go with a whole house inverter/charger; and if lithium is in near future, should check compatibility.

Peter
 
We have a 3000 watt modified sine wave that we manually switch runs fine for fridge and coffee think we may install true sine wave if we do more cruising of interest is using a Bluetti and a dc To dc charger
 
You'll need to think though what you really want to power. I am sure you have ideas of what would be "nice" to power however that may get you into a rebuild of your house bank which may or may not be something you want to do. So you could do something as simple as 1,000 watt inverter to run a small 700 watt microwave or go much larger and be able to power air conditioning. One thing I learned about this year is both Victron and Renogy have models with an ECO function. In essence the ECO mode puts the inverter to "sleep" and draws a tiny amount of amps until an X size load is called for from the inverter. When an inverter is on it's always drawing some power even through there is no load on it. So ECO modes can help minimize the total amp load on your batteries.

If you are not sure about amp draw here is a simple example for a 700watt microwave running for 5 minutes to unthaw dinner items. 700 watts at 12.5 volts draws 56 amp hours(Watts = Volts X Amps) or .933 amps per minute. So with 5 minutes of runtime at .933 amps per minute you'd consume 4.7 amp hours from the battery bank. Your voltage may be different which will change the math for amps consumed as will inverter efficiency. Newer inverters are about 90% efficient so that needs to be factored in too. However for a ballpark estimate at 700 watt load will consumer about 1 amp hour per minute from the battery bank.
 
As you have seen there's a large range of applications here, from large multi thousand dollars systems to a simple inverter.

A killawatt meter will help you determine how much amperage each one of your applicances actually draws. They are available on amazon. I often use a small Cuisinart coffee maker that only needs 5 amps. Makes two cups of coffee. A small Xantrex inverter in the 1500 to 2000 watt range will do that.

A pure sine wave inverter is more efficient than a modified sine wave and worth the extra expense in my opinion. Also better for any electronic devices you might use with it.

Right size the cabling, extremly important. There are tables that you can look at on West marine and other places to help with that.

If you go for a more elaborate system you might want to factor in a battery monitor from Victron or Balmar so you know how much capacity your batteries have and how much applicances draw. An elaborate system may take more skill than you have, be honest with yourself about that.

If you hire it out I would suggest that the tech be certified by ABYC.

-martin610
 
Another vote for Magnum. I've had a 3.1 modified sine wave for 10 years with no problems. Runs the hotel loads while on the hook fine.
 
Like the ABYC LFP thread TT started, this has developed into an informative thread. A comment I might add for the long distance cruisers:

Once you've got your wiring, switches, battery bank and type, inverter/charger, charging systems, genset, solar panels and monitoring devices all to a pro's liking -- buy an identical inverter and store it onboard.

Why?
- Inverters are cheap,
- not easily available in far off ports or anchorages,
- prone to failure,
- of limited lifespan,
- abused and
- the lifeblood of most up to date electrical systems.

Redundancy is oft talked about for parts such as bolt on engine equipment, plumbing, toilet etc. Likewise, backup (work around) parts and systems should be the same for mission critical electrical gear. If your cruising grounds are near a well-stocked port or two, a tow boat service or you're a dock sitter redundancy becomes of lesser importance.
 
My refrigerator woes have led me to believe that a dedicated inverter sized for the AC only fridge is smart. It both produces the AC more efficiently than my big 3000 watt inverter and provides some redundancy.
 
Here are some thoughts, but keep in mind that I tend towards creating more expansive systems. A lot can be done with less, and you will need to decide how far you want to go, and in what steps. But I'll predict that whatever steps you take today that you think are sufficient, a year from now you will be looking at taking the next step, then the next, then the next. Having onboard AC power is a slippery slope towards convenience, comfort, and enjoyment of your boat. So beware, danger lies ahead...


I would lean towards a larger inverter, not a smaller one. I'd got at least 3kw, and perhaps 5kw. Once you have it, you will use it and enjoy it. Don't cut yourself short.


Install a bypass switch that will pass shore or generator power around the inverter and power your loads. It's an important backup in case the inverter has issues, plus a convenient and safe way to have power onboard while working on the inverter.


Rather than picking a few things that you want to be inverter powered, pick the few things that you absolutely do NOT want to be inverter powered. This list probably includes nothing more than 1) electric hot water heater, 2) HVAC, 3) shore charger(s). I would put EVERYTHING else on the inverter. Now this will be influenced by how your boat is wired, and you will need to find a happy median. For example, it's common for HVAC to be on a separate shore power circuit, so that's easy to keep off the inverter. A hot water heater and shore chargers may be more difficult. In some cases you may want to leave the hot water heater on the inverter, but remember to turn it off when not on shore or gen power.


Get an inverter/charger, not just an inverter. When wired correctly, the inverter/charger will automatically detect the presence of shore or gen power, switch the loads over to that power source, and start charging the batteries. It's super convenient, and transparently hands loads off between inverter and shore power.


Once you have an inverter, you will need to keep an eye on your batteries because you will be using them more. And as you use more and more AC power through the inverter, you are likely going to want to grow you battery bank size, increase charging capability, etc.
 
SteveK said:
TT what is your opinion on electric 110 stoves, invert or not.
Click to expand...


I don't have mine on the inverter, but given enough battery capacity to run at least 1 burner on inverter power for a useful length of time (and ideally more solar), I probably would.



So I'll put that one down as "if you can handle powering it from battery / solar, then put it on the inverter, otherwise don't"
 
rslifkin said:
I don't have mine on the inverter, but given enough battery capacity to run at least 1 burner on inverter power for a useful length of time (and ideally more solar), I probably would.



So I'll put that one down as "if you can handle powering it from battery / solar, then put it on the inverter, otherwise don't"
Click to expand...

Thanks rslifkin. I have done my circuits like TT suggests on the Magnum inverter/charger, so it is already downstream from inverter. My question was opinion on running with inverter. Hot water tanks are not efficient to be run from invert.
The inverter/charger senses load and reduces charger output, that was my goal as before I would turn on the genny and charger wanted priority not sensing that we wanted to cook.
Looking to see if cooking from inverter, other than battery capacity is a concern.
 
SteveK said:
TT what is your opinion on electric 110 stoves, invert or not.
Click to expand...


I probably would since cook-top cooking typically doesn't last that long. Running an electric over would take more since running for an hr or more isn't uncommon.


Also consider that if it's on the inverter, you can still start a generator and it will carry the load. So you can run it either way.
 
twistedtree said:
I probably would since cook-top cooking typically doesn't last that long. Running an electric over would take more since running for an hr or more isn't uncommon.


Also consider that if it's on the inverter, you can still start a generator and it will carry the load. So you can run it either way.
Click to expand...
Also, consider a single hob induction burner for use when off-grid. About 40% more efficient than resistance coil thus much easier to support with inverter/battery. Modest changes to cooking to use an instant pot or crock pot are also helpful.

Peter 20221222_092614.jpg
 
Big inverter and big battery is a no brainer IMHO and in the scheme of boat bucks, cheap given the 24/7 utility they provide.

For around $10k including pro install we have
2500w of solar
Victron 5000/120 inverter charger
Midnite classic 150 mppt charger
840ah @ 24v of lifepo4 battery

That allows pretty much a 240v boat to run multiple fridge freezers, electric galley, watermaker, washing machine, multiple PC and screens, hot water system etc etc

Nothing turned off, no load sharing (within reason) and Genset only required on the rainiest of days.

Obviously smaller boats, less refrigeration , less loads wouldn't need to spend as much.
 
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