What’s the cheapest and easiest to install inverter?

Hey guys. I know that a proper inverter is great to have and is costly for a reason. But I want something just as a back up to our generator. If our gen dies at night, I want a way to power our fans, run the fridge and also charge our phones.

Having this inverter would also be really nice so we wouldn’t have to run the generator as often.

Thanks guys!

Steve91T said:

I want something just as a back up to our generator. If our gen dies at night, I want a way to power our fans, run the fridge and also charge our phones.

Having this inverter would also be really nice so we wouldn’t have to run the generator as often.

Thanks guys!

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An inverter will never be a backup source of power. It will always be a consumer (just leaving it turned on with no loads will consume battery power) or at best a way to change your DC power source into an AC power source. Never forget that every watt of AC that you use through your inverter costs your batteries and will require you to find a source of replacement wattage that will exceed the used wattage.

Your genset will get more use with an inverter than without.

Alternative sources of power may be Solar, Wind generator or just staying where you can be plugged into shore power.

koliver said:

An inverter will never be a backup source of power. It will always be a consumer (just leaving it turned on with no loads will consume battery power) or at best a way to change your DC power source into an AC power source. Never forget that every watt of AC that you use through your inverter costs your batteries and will require you to find a source of replacement wattage that will exceed the used wattage.

Your genset will get more use with an inverter than without.

Alternative sources of power may be Solar, Wind generator or just staying where you can be plugged into shore power.

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I’m sorry I didn’t word that correctly. What I want is something to get us through a night if the generator dies. We’d loose air conditioning but at least we’d have fans and the fridge will continue to work.

Starting engines the next morning will charge batteries back up. And if the generator was really dead, we’d just spend the next night at a marine and plug in.

I think what Koliver is saying is that unless you have enough house battery to run the equipment on inverter, then you won’t get far enough on inverter, and will damage your batteries in the process.

Most fans are DC and also many fridges. But if the fridge is AC only it probably draws 2-3 amps, call it 360 watts peak and cell phone charging will require maybe another 100 watts. So a cheap 500 watt Chinese inverter will do the job. Here is a page of them for under $50.00:

https://www.amazon.com/s?k=500+watt+inverter&crid=2R716B6FA1VD6&sprefix=500+watt+inv%2Caps%2C177&ref=nb_sb_ss_i_1_12

500 watts is too much to plug into a cigarette lighter socket so you will have to clip on to the battery somehow, and you will have to figure out how to unplug your fridge from shore power and plug it into the inverter.

Not so convenient but on boats, convenience costs money.

David

Some kind of "portable" inverter that is made to clamp directly to a battery. A few extension cords may do it, but as mentioned, you'll have to figure that out.


Ken

The better solution would be installing DC fans and a proper AC/DC marine fridge.

In the PNW if someone is running a generator after 9-10 pm it’s considered offensive. Having cruised in the BVI, I understand the need, and the acceptance of running a generator all night.
On Glauben, for “house” use batteries I have two systems. There is the normal house system where I have 4 golf cart batteries that recharges off the alternator, generator or shore power. Then there is a completely independent inverter system that has a Freedom 2500 inverter and four golf cart batteries. The outlets, refrigerator and microwave are on that circuit. If the generator is running, those batteries are charging. The generator is an 8.5kw Onan.
I’m good for a full two days, maybe more, I haven’t done more than two days, running off the inverter. With the lights and fans connected to the house batteries and the tv, coffee maker, ac lighting, and everything the Admiral wants to plug in, did someone say hair dryer, we are good.
When you install the inverter, the neutral wires for the inverter load also needs to be on a separate buss from those not being used by the inverter. Same as the load wires. It has to do with the time it takes for the inverter to realize there is ac available. In the no ac available condition the inverter goes to a ground fault to operate.

Most cheap, low wattage inverters aren't going to start the motor on a household fridge. The motor requires a surge of current to be available at startup. 1000W minimum is recommended, but with research and reading reviews of users who actually try them on fridges, you might get away with a 600W unit of good quality. I've used Aimspower inverters in applications where budget is driving and had good results. Their 1000W model should be sufficient to start a fridge and run a couple of fans.

https://www.aimscorp.net/1000_Watt_Pure_Sine_Power_Inverter_12_Volt.html

I'd call and ask them for their recommendation to run your fridge, they have good customer service in my experience, they cater to the RV industry. I'm not affiliated.

Keep in mind also that you need a 'transfer' function to have the inverter automatically take over if the genset is shutdown. Those units have an AC input as well as an output and patch power through when the generator is running, and automatically turn on when the genset is not running. Without that your options for how to get the fridge running on one or the other may be limited to moving the plug manually.

I have a mix of 12V and 120V fans. My TV, stereo, cameras and WIFI are all 12V. One fridge is 12V/120V and the other fridge, my 'beer & bait fridge", is 120V inverter powered when there's no shore power. No AC or diesel heat aboard.

I installed a cheap, POS Xantrex 1000W MSW inverter which only powers items on my aft countertop - a 120V 4cu ft fridge, microwave, fan and charge cords for phones, tablets, flashlights, etc. I can also power a coffee maker or electric skillet with it if I'm not using the microwave simultaneously. It is not wired into the boat 120V system but provides separate power to the countertop. Since it only cost me $100 and had been known to fail, I've got a spare onboard protected in shrinkwrap. The most recent replacement has been there for over 4 years and is still going strong. (knock on wood)

Generally, I prefer 12V power to 120V power when able and performance is satisfactory. If it's got to be 120V, then in my world, smaller is better.

I have Rigid 18 volt power tools, primarily because they have lifetime service on them. Rigid makes a hybrid fan that will work on either the 18V battery or 120V. Have not actually used it aboard the boat yet but with 1 or 2 batteries it should run all night. Since I have lots of batteries it should work ok.

Shrew said:

The better solution would be installing DC fans and a proper AC/DC marine fridge.

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Additional battery capacity and a decent inverter will most likely work out better value.

While we are on the subject, sort of, I use a Xantrex/Heart system for charger and inverter attached to the stbd start and house but not the port engine start battery. The Stbd start battery is a D8 and is included in the house bank with two other D8s. There was an old charger that existed to keep the Port start batt up to snuff but it just died. So now it only charges off of the port alternator. Any suggestions for a replacement charger?

RickyD said:

While we are on the subject, sort of, I use a Xantrex/Heart system for charger and inverter attached to the stbd start and house but not the port engine start battery. The Stbd start battery is a D8 and is included in the house bank with two other D8s. There was an old charger that existed to keep the Port start batt up to snuff but it just died. So now it only charges off of the port alternator. Any suggestions for a replacement charger?

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Unless there is some other load or draw on that port start battery, do you actually need anything besides the alternator?

RickyD said:

There was an old charger that existed to keep the Port start batt up to snuff but it just died. So now it only charges off of the port alternator. Any suggestions for a replacement charger?

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You could probably get by with a selectable combiner. I have a single bank house charger and twin alternators dedicated to each bank. I use a combiner to share the house charge with the start batt when present but I can deselect it if the start batt is sufficiently charged...which is normally the case.

Blue Seas and Yandina are two good brands.

When you say "fans" do you mean the blowers on the air conditioning units or just portable 120VAC household types? The blowers will need some type of switching relays; not used in the cheapo inverter types. Household portable fans would work fine.

High Wire said:

When you say "fans" do you mean the blowers on the air conditioning units or just portable 120VAC household types? The blowers will need some type of switching relays; not used in the cheapo inverter types. Household portable fans would work fine.

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I mean desktop style fans to keep hot humid air moving instead of stagnant.

Create boat power use spreadsheet in amp hours per hour for all loads. then multiply by 24 to give you one 24 hours at. Say that gives you 250 total amps. Expand house bank to 500 amps understanding you can draw down your lead acid battery bank by 50 percent max before recharging. Now if you want 2 days on batts house needs to be 1000 ahr.

I run my generators a lot less with an 48v inverter system. PO ran a generator 24/7. I have a dedicated alternator on one of the mains that keeps the banks up while cruising. I original ran a generator while running the mains. Now I run a generator about an hour a day, usually when making water or doing laundry. But I don't go where it's hot enough to run AC. Almost everything on my boat is 240/120 AC. Thinking of adding a wind turbine and solar, then I'd rarely run the generators.

The 1500W units sold at most truck stops will handle everything you have listed.

Here is an example,

https://www.homedepot.com/p/Power-B...PIPHorizontal2_rr-_-202539671-_-202539673-_-N

They will also work for blenders , microwave (reheat , not cook your batts are probably too small.Most will operate smaller power tools drill, sander and even charge power tool batts.

.Most will double their output for the time required to start a heavy load like an air compressor

Since the inverter will operate from the alt , with engine operation many AC items can be left to the next boat movement

On line they can be found for about $150 or so.

They are NOT sine wave units but those are mostly for heavy motors , water maker, scuba tank fill etc

I would oversize the cables to the battery so in the future you decide on a bigger fancy unit it will be a bolt in.

FF said:

The 1500W units sold at most truck stops will handle everything you have listed.

Here is an example,

https://www.homedepot.com/p/Power-B...PIPHorizontal2_rr-_-202539671-_-202539673-_-N

They will also work for blenders , microwave (reheat , not cook your batts are probably too small.Most will operate smaller power tools drill, sander and even charge power tool batts.

.Most will double their output for the time required to start a heavy load like an air compressor

Since the inverter will operate from the alt , with engine operation many AC items can be left to the next boat movement

On line they can be found for about $150 or so.

They are NOT sine wave units but those are mostly for heavy motors , water maker, scuba tank fill etc

I would oversize the cables to the battery so in the future you decide on a bigger fancy unit it will be a bolt in.

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The pure sine versions have gotten so much cheaper, spend another $50 to get a good one. The modified sine cheapies are terrible. The OPs questions is which is easiest and cheapest to install, to meet the objective of running a fridge and a couple of fans.

I think that the answer to that is a 1000W pure sine unit that clips onto the house bank with standard battery spring clamps. Unplug your items from the standard outlet and plug them into it when needed. That's the simplest, cheapest option, can be had for $130-$250 depending on quality and 'installs' in the time it takes to get access to the house bank. 1000W should be able to provide enough startup current for the fridge.

Convenience wise, not probably so great, but additional installation complexity for a proper installation (make up DC cables with bolt-on terminals, circuit protection (ANL fuse), install AC into transfer switch, etc....) don't meet the original question.

Don't rely on "clips". Always hard wire your inverter using properly sized and fused cables and terminals.

FlyWright said:

Don't rely on "clips". Always hard wire your inverter using properly sized and fused cables and terminals.

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Agreed. But in the spirit of the original question, that's literally the easiest to 'install'.

A proper install involves making up or buying cables of appropriate gauge, putting a fuse block in to protect the boat from the wire, mounting the inverter unit on a bulkhead somewhere, and dealing with the A/C side properly. Not exactly simple.

I'm not sure I would want to install an inverter that was selected solely because it is cheap and easy to install. Using clamps to battery has no circuit protection.

I had a "not cheap" Magnum 2812 inverter, properly installed, experience a meltdown a few years back

I wrote about it in the thread; List of “good” inverters please

sbman said:

Agreed. But in the spirit of the original question, that's literally the easiest to 'install'.

A proper install involves making up or buying cables of appropriate gauge, putting a fuse block in to protect the boat from the wire, mounting the inverter unit on a bulkhead somewhere, and dealing with the A/C side properly. Not exactly simple.

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That's not installed, it's clipped on and unsafe! If you think doing it right is expensive, try doing it wrong and paying the price with loss of property or life or limb. Not worth the risk when you're out there alone on the water.

Safety first - so you can enjoy the rest of the day.

yep, the Xantrex in our boat was dead when we purchased her (price adjusted accordingly). PO had installed a stand alone battery charger (properly installed). We did not want a combo inverter/charger, so kept the existing charger and installed a 3000w AIMS pure sine wave inverter - with remote installed at lower station. Installed a battery cut-off switch between batteries and inverter also. Did not want an inverter with auto-transferring - have seen too many that caused problems with new marina GFCI installations. Three circuits can be powered by our inverter - fridge, ice maker and AC outlets (fans, lamps, microwave..). Our electrician provided a switch that prevents me from making a big mess. Switch is "inverter", or 'Panel" - ie those 3 circuits get their power from the breaker panel as usual (shore or generator), or from the inverter, but not from both House bank (4 new 225AH golf cart bats) supplies the inverter. System is working great.

Our electrician is a bit OCD (good thing). He and I calculate the load and battery wire size required - then ups it to the next bigger size cable�� No clips - permanently direct wired.

The inverters with the built in transfer relay are simple. You can put them in line with your breaker and its fairly easy setup. Shore power cuts out it switch's over automatically and your good to go. There well under 1K and will work correctly. Its not hard to do yourself if you read the manual, but its also one of those things that you should pay to have done right if your not good at electrical work. With this particular item going it on the cheap is not a good idea. In my experience the little cheap ones for cars ext with the battery clips will either fry on you instantly, or just keep tripping over themselves - waste of time and money.

While the DC side will draw big amperage , and should be properly installed with cables , most small inverters have a pair of 120v 15A house normal sockets built into the unit.

There is zero real need for AC complexity , transfer switching etc.

Simply plug in to the inverter sockets and enjoy the usual digital volt meter to see how the battery is fairing.

For the fridge having an extension cord that could be moved from the shore powered socket to the inverter would work fine.


Be sure to get return ability as some inverters make RFI, noise that your radio or TV or electric piano may amplify.

Cheap and easy are left to aspects of life associated with land life ...no such thing on watercraft .... Unless of course safety and reliability is of little concern.

Thanks everyone for the help. This all helps a lot. I really wish the PO had installed a dual voltage fridge, but I know that an an apartment size fridge is really expensive. His mentality was that diesel is cheap, just run the gen. I don’t blame him.

One thing that I haven’t paid much attention to is that I might actually have a couple of 12v outlets. There are two outlets, one in each bathroom that are labeled 12v, and I do have an “outlets” breaker that’s on the DC side. I just do t have anything that’s 12v that plugs in to try.

How do I figure out how much one of those plugs can handle? I’m sure they’ll run some fans, but doubt the fridge will work.

We are getting ready to move the boat from Ft Myers across the lake to the east coast then up to somewhere north of Jax. We’ll do it over several small trips. I was just wanting to have a back up plan if the gen has issues.